GIS DEVELOPMENT GUIDE: MANAGER'S OVERVIEW

1 INTRODUCTION

This guide is the first of a set of technical support documents to assist local governments in developing a GIS. The set of guides describes procedures and methods for planning the GIS, evaluating potential data sources, testing available hardware and software and planning for its acquisition, building the GIS data base, developing GIS applications, and planning for the long term maintenance of the GIS system and data base. These guides are intended to provide advice on how best to accomplish the GIS development tasks for all levels of local government - from large,urbanized counties to small rural towns to special-purpose districts.

Realistically, large comprehensive GISs will be developed by the larger units of government (counties and cities) individually or, most likely as the leader in a cooperative multi-participant effort. These would involve the individual operating units within that government and/or the smaller units of local government within the common land area of the larger leading unit. Typically, we would expect to see county government taking the lead, but also covering the interest of all other governmental units within the county. Occasionally, there will be situations where smaller units of government (town, special purpose district, or limited purpose GIS application) may have to "go-it-alone" in developing the GIS. These guidelines have been written to mainly address the first case - a county leading a consortium or cooperative effort. Thus, we would expect the GIS development team of a county to be the primary user of these guidelines, in the sense of actually performing the tasks outlined in each document. However, this does not mean the other participants in a GIS should stop reading these guidelines at this point. It is critically important for all expected participants in a cooperative GIS venture to fully understand the development process. If a smaller unit of government is to reap the benefits of a county-level GIS, they must actively participate in the planning and development effort.

The procedures are applicable for use in first-time creation of a GIS, for restructuring an on-going GIS development project, and for the review and further development of an existing GIS. The subject matter of the guides identifies the necessary tasks in a GIS development program, describes appropriate methods to accomplish each task and, where applicable, provides examples and illustrations of documents or other products that result from each task.

The guidelines are designed for use by general-purpose local governments (city, county, town, or village), special purpose governments (utilities, school districts, etc.), and by those who provide assistance to local governments (consultants, academic units, etc.). The guides address the technical steps required to create a GIS, the management tasks required to ensure successful development of the GIS, and the policy issues that should be considered for the effective use of the GIS.

The Role Of Management

Although GIS is often viewed as an arena for the technically sophisticated computer professional, the development of a successful government-based multi-participant GIS is very dependent on proper management participation and supervision. Normal, common-sense management practices are as necessary in a GIS project as in any other major undertaking. In fact, our experience has shown that the recommended management actions may be the most critical aspect of the GIS development process. GIS development is a process of technological innovation and requires management attention appropriate to this type of activity - active as opposed to passive management involvement in the project. Historically, much of the disillusions and disappointment with GIS projects stems not from a failure of the technical components of the GIS but rather from a lack of understanding of the process of technology innovation and the lack of realistic expectations of all parties associated with the project (GIS technicians, potential users, managers, and elected/appointed officials).

Applying The GIS Development Guides By Local Governments In New York State

The overall procedure contained in the GIS Development Guides is very comprehensive and can require considerable time, effort and dollars to complete. This raises the questions:

• Does all of this have to be done?
• What level of detail is appropriate?
• How can smaller governments,villages and towns, special purpose districts, or a single department in a larger jurisdiction, get through this process?

Does everything have to be done? . . level of detail?

Basically, yes. However, the steps in the GIS development process are frequently done in an iterative manner over an extended time period. Also, the steps are not completely independent of one another and so some back-and-forth does happen. It is often useful to make a "first-cut" run through the entire process, writing down what is already known and identifying the major questions that need to be answered. The person who will be managing the development process may be able to do this "first-cut" description in 1 to 2 days. This can be very helpful in getting a feel for the scope of the whole process and then can be used as a decision tool for continuing. The number of times the process is conducted, the amount of detail, and the resources needed to complete the study can be balanced in this way. If the intended implementation will be limited or small, the planning effort and documents can be sized accordingly. It is important, however, that each step be considered and completed at some level. The companion GIS Design software package that accompanies these guides provides a structure and makes it easy to record the information developed during the planning process - application descriptions, data model, data dictionary, meta data, logical database design, and record retention information.

How can smaller units of local government, such as villages and small towns complete a GIS Plan?

The best situation for a village, small town, or even a smaller, rural county is to be a partner with a larger unit of government, a county, regional agency or utility company that is conducting and/or leading a GIS planning exercise. Participating in a regional GIS cooperative, or joining an existing one, will provide access to GIS technical expertise and spatial data created by other agencies. Additionally, if one is a partner in a larger group, the activities directed toward the evaluation and selection of the GIS hardware and software may not need to be completed. One would simply use the same GIS system in use by the larger agency or group. Only the activities aimed at defining applications (uses) and identifying the needed data would need to be done by the smaller unit of government. In such a situation, the larger unit of government assumes the leadership role for the area-wide GIS and should have the technical expertise to assist the smaller unit. In situations where a larger effort does not exist, a village or town government may want to look at a GIS installation in a similar village or town elsewhere in the state. Given the similarities in local governments within the state, the adoption of the GIS plan of another unit is not unreasonable. That plan should be carefully reviewed by the intended participants in the GIS to ensure applicability. After modifying and validating the plan, a schedule for GIS hardware, software and data acquisition can be prepared consistent with available resources. If a good plan is prepared, there is no reason data acquisition (the most expensive part of a GIS) cannot be stretched over a long time period. Significant data already is available from state and federal agencies at reasonable costs. These data can form the initial GIS database, with locally generated data added later. A list of state and federal data sources is contained in the Survey of Available Data Guide.

Content Of This Guide

This guide presents an overview of the GIS development process. This process is presented as a sequence of steps conducted in a specific order. Each step is important in itself, but more importantly, information needed to complete subsequent steps is assembled and organized in each previous step. The underlying philosophy of the entire series of documents is to concentrate on the GIS data. As well as being the most expensive part of any GIS, the data must be collected, stored, maintained, and archived under an integrated set of activities in order to ensure continued availability and utility to the initial users as well as future users, including the general public. Defining and documenting data elements from their initial definition in the needs assessment through to proper archiving of the GIS database according to state requirements is the constant theme of these guidelines.

2 GEOGRAPHIC INFORMATION SYSTEMS: DEFINITIONS AND FEATURES

Basic Definition Of A Geographic Information System (GIS)

A geographic information system (GIS) may be defined as "...a computer-based information system which attempts to capture, store, manipulate, analyze and display spatially referenced and associated tabular attribute data, for solving complex research, planning and management problems"(Fischer and Nijkamp, 1992). GISs have taken advantage of rapid developments in microprocessor technology over the past several decades to address the special challenges of storing and analyzing spatial data. Geographers have referred to GISs as simultaneously providing "...the telescope, the microscope, the computer and the Xerox machine" for geographic and regional analysis (Abler, 1987).

Unique Features Of A GIS - Why Planning Process Is Needed

GIS belongs to the class of computer systems that require the building of large databases before they become useful. Unlike many micro-computer applications where a user can begin use after the purchase of the hardware and software, the use of a GIS requires that large spatial databases be created, appropriate hardware and software be purchased, applications be developed, and all components be installed, integrated and tested before users can begin to use the GIS. These tasks are large and complex, so large in fact,as to require substantial planning before any data, hardware or software is acquired. The focus of the GIS Development Guides is to describe the GIS planning process and to provide examples of how to accomplish the recommended planning tasks.

History Of Technology Innovations - GIS Is A Technology Innovation

It is useful to note that GIS is, at present, a technological innovation. The adoption of technological innovations (i.e., the development of a GIS for a local government) is not always a straightforward process, such as one might expect with the installation of something that is not new. Several problems are likely to occur such as:

• Staff not fully understanding the technology prior to extensive training
• Development time estimates differing from actual task times
• Greater uncertainty about costs
• A greater likelihood that programmatic changes will be needed during the development phases, etc.

The significant management point here is that these are normal conditions in the adoption of a new technology. Management needs to anticipate that such events will happen, and when they do, take appropriate management actions.

The adoption of computer technology by an organization either GIS or other applications, introduces fundamental change into the organization in its thinking about data. Prior information technology allowed data to be collected and related to activities and projects individually. Organized stores of data were the exception rather than common practice. This led to duplicate data collection and storage (as in different departments) and to the possibility of erroneous data existing in one or more locations. One of the goals of computer systems and database development is to eliminate redundant data collection and storage. The principle is that data should be collected only once and then accessed by all who need it. This not only reduces redundancy; it also allows for more accurate data and a greater understanding of how the same data is used by multiple departments. The necessary condition for successful computer system and database development is for different departments and agencies to cooperate in the development of the system. A database becomes an organization-wide resource and is created and managed according to a set of database principles.

3 ENTERPRISE-WIDE GIS: THE CORPORATE DATABASE

The role of a GIS in a local government setting is more than simply automating a few obvious tasks for the sake of efficiency. A local government (or several cooperating governments) should view the GIS project as an opportunity to introduce fundamental change into the way its business is conducted. As with the adoption of management and executive information systems in the business world, the adoption of GIS effectively reorganizes the data and information the government collects,maintains and uses to conduct it affairs. This can, and arguably should, lead to major changes in the institution, to improve both effectiveness and efficiency of operations.

A key factor in the success of computer system adoption in the business world is the concept of the"enterprise" or "corporate" database. As implied by the name, the corporate database is a single,organization-wide data resource. The advantages of the corporate database are first, that all users have immediate and easy access to up-to-date information and, secondly that the construction of the database is done in the most efficient manner possible. Typically, the corporate database eliminates redundant collection and storage of information and the keeping of extra copies of data and extra reference lists by individual users. Here, we are recommending the use of corporate database concept to integrate GIS data for all units of local government participating in a cooperative GIS program.

An effective corporate database does require cooperation on the part of all users, both for the collection and entry of data in the database and in developing applications in a shared data context. This may result in some individual applications or uses being less efficient, however the overall benefits to the organization can easily outweigh these inefficiencies. Greater emphasis must,however, be placed on maintaining a high quality of data and services to users, mainly to offset the perceived loss of control that accompanies sharing an individual's data to another part of the organization.

The corporate database concept can be used in the governmental situation, for either single units of government or between several governmental entities in the same region. The benefits associated with the corporate database can be achieved if governmental units are willing to cooperate and share a multi-purpose regional GIS database. Such an arrangement has some technical requirements; however, establishing the corporate database is much more a question of policy , management cooperation and coordination.

4 POLICY ISSUES IN GIS DEVELOPMENT

There are several policy issues that need to be addressed early in the GIS planning process:

GIS Project Management

Adequate management attention has already been mentioned in this document. As GIS is still an evolving new technology, the individuals involved (management, users, GIS staff) may have very different expectations for the project, some based on general perceptions of computing, which mayor may not be correct. This, along with the long time period for developing the GIS, makes it very important for substantial involvement of management in the project. Several factors associated with successful GIS projects are:

• Emphasize advantages of GIS to individual users and entire organization
• Require high level of competency by all participants
• Ensure high level of management commitment from all management levels in the organization
• Require participation in team building and team participation within & between departments
• Ensure minimum data quality and access for all users
• Require development team to set realistic expectations
• Minimize time between user needs assessment and availability of useful products.
• Develop positive attitude toward change within organization
• Ensure level of technology is appropriate for intended uses
• Highly visible Pilot Project that is successful

Data Sharing

The sharing of data among government agencies is a virtual necessity for a successful, long-term GIS. Not even the most affluent jurisdictions will be able to justify "going-their-own-way" and not taking advantage of what data are available from other sources or not sharing their database with other governmental units. This, then, raises several questions that must be considered during the planning of the GIS:

• What will be the source for each data item?
• How will sharing be arranged? . . purchase? . . license? . . other agreement?
• Who will own the data?
• How will new GIS data be integrated with existing data files (legacy systems)?
• Who will be responsible for updates to the data?
• How will the cost of the data (creation and maintenance) be allocated?
• Who will provide public access to the data?
• Who will be responsible for data archiving and retention? . . of the original? ..of copies?

These questions do not, at this time, have good answers. Currently, the Freedom of Information regulations require that all government data be made available to the public at minimal cost (cost of making a copy of the data). No distinction is made on the basis of the format of the data (eye-readable or digital), the amount of data, or the intended use of data. Thus, the question of sharing the cost of a GIS database cannot be addressed in general. If data can be obtained free from another agency, why enter into an agreement to pay for it? The answer is, of course, that the creating agency will not be able to sustain the GIS database under these circumstances. However, at this time , the set of state laws and regulations applicable to GIS data are not adequate to resolve cost issues and to facilitate regional data sharing cooperatives. New legislation will be required. The New York State Temporary GIS Council did submit recommendations on these issues to the Legislature in March 1996. Additionally, the New York State Archives and Records Administration is currently in the process of preparing record management and retention schedules suitable for GIS data, both in individual agencies and for shared databases. The New York State Office of Real Property Services has been designated as the GIS representative on the Governor's Task Force for Information Resource Management. One of the charges that has been given to the Task Force is to design a cohesive policy for the coordination of geographic information systems within New York building on the work of the Temporary GIS Council. Further information should be available in late-1996 that should clarify the issues associated with arranging for data sharing among governments.

5 MANAGEMENT ISSUES IN GIS DEVELOPMENT

Expected Benefits From The GIS

Local government need for, and use of, a GIS falls into several categories: maintaining public records, responding to public inquiries for information, conducting studies and making recommendations to elected officials (decision-makers), and managing public facilities and services(utilities, garbage removal, transportation, etc.). The GIS tasks that meet these uses are:

• Providing regular maps
• Conducting spatial queries and displaying the results
• Conducting complex spatial analyses

Many of these tasks are already done by local government, although by manual means. The GIS is able to perform these tasks much more efficiently. Some of the analytical tasks cannot be performed without a computer due to their size and complexity. In these cases, the GIS improves local government effectiveness by providing better information to planners and decision-makers.

Benefits from using a GIS fall into the two categories of: efficiency and effectiveness. Existing manual tasks done more efficiently by the GIS result in a substantial savings of staff time. In the local government context, the largest savings come from answering citizen inquiries of many types. Depending on the size of the government, savings using the query function of a GIS can range from 2 person-years for a smaller town, to 5-8 person years for a large town, to 10 or more person-years for a large county. Estimates of potential time savings can be derived by measuring the time to respond to a query manually and by GIS and multiplying the difference by the number of expected queries. This information is usually gathered during the Needs Assessment. Effectiveness benefits are more difficult to estimate. The GIS may be used to accomplish several tasks that were not previously done due to their size and complexity (e.g., flow analysis in water and sewer systems,traffic analysis, etc.). As these are essentially new tasks, a comparison between manual and GIS methods is not possible. While not measurable, the benefits from these applications can be substantial. Generally categorized as better planning, better or more effective decision-making,these applications support more effective investment of government resources in physical infrastructure where relatively small performance improvements can translate into large dollar savings. GIS also provides an effective way to communicate the problem and solution to the general public and other interested parties

Resources Required To Develop A GIS

Developing a GIS involves investment in five areas: computer hardware, computer software,geographic data, procedures and trained staff. The acquisition of the computer hardware and software are often incorrectly viewed as the most expensive activity in a GIS program. Research, some conducted at the National Center for Geographic Information and Analysis at SUNY-Buffalo, has demonstrated that developing the geographic database (which includes some of the procedure and staff costs) can account for 60% to 80% of the GIS development costs. Continuing costs for operation and maintenance are also dominated by the data costs. Coordination of GIS programs,particularly among several local government agencies, can minimize the cost of database construction and maintenance, and can provide for the greatest use of the database, which gives maximum benefits from the investment.

Staffing Requirements For A GIS

Staffing for a GIS is a critical issue. In general, it is not easily feasible to directly expand the local government staff positions to fill the GIS need. There are three areas where expertise is needed:

• Management of the GIS project (GIS project manager)
• GIS database skills (usually called a database administrator)
• Application development for database and users (a GIS software analyst)

Initial creation of the GIS database (digitizing) will require an appropriately sized clerical staff, dependent on the amount of data to be converted. Alternatives to staff expansion are consultants and data conversion firms. GIS database conversion is a front-end staff need that can easily be contracted-out (good quality specifications need to be written for this task). If at all possible, the three functions of GIS manager, GIS software analyst and GIS database administrator should be fulfilled by staff personnel, either by hiring or by retraining existing professionals. When necessary, during the start-up phases of GIS development, the GIS analyst and database administrator functions can be done under consultancy arrangements, PROVIDED THAT A FULL-TIME GIS MANAGER IS AVAILABLE ON STAFF.

The second need is for training of users in general computing, database principles, and GIS use. These topics are covered in training courses offered by most GIS vendors, and after the GIS software has been selected, they are the best source for user training.

Management Decision Points in the GIS Development Program

The "decision" to develop a GIS is made incrementally. The information needed to determine the feasibility and desirability of developing a GIS is not available until several of the planning steps have been completed. The key decision points are:

• Decision to investigate GIS for the organization - the initial decision to begin the process. This is an initial feasibility decision and is based on the likelihood that a GIS will be useful and effective. It is fairly important to identify the major participants at this point - both departments within agencies and the group of agencies, particularly key agencies, the agencies who represent a majority of the uses and who will contribute most of the data.
• Decision to proceed with detailed planning and design of the database - at this time, the applications, data required, and sources of the data have been identified. Applications can be prioritized and scheduled and the benefits stream determined. Also, applications to be tested during the pilot study and the specific questions to be answered by the pilot study will have been determined. A preliminary decision will need to be made as to which GIS software will be used to conduct the pilot study.
• Decision to acquire the GIS hardware and software - this decision follows the preparation of the detailed database plan, the pilot study and, if conducted, the benchmark test. This is the first point in the development process where the costs of the GIS can reasonably be estimated, the schedule for data conversion developed, and targets for users to begin use determined.

6 GEOGRAPHIC INFORMATION SYSTEMS: THE DEVELOPMENT CYCLE

Developing a GIS is more than simply buying the appropriate GIS hardware and software. The single most demanding part of the GIS development process is building the database. This task takes the longest time, costs the most money, and requires the most effort in terms of planning and management. Therefore the GIS development cycle presented here emphasizes database planning. Most local governments will acquire the GIS hardware and software from a GIS vendor. Choosing the right GIS for a particular local government involves matching the GIS needs to the functionality of the commercial GIS. For many agencies, especially smaller local governments, choosing a GIS will require help from larger, more experienced agencies, knowledgeable university persons and from qualified consultants. By completing selected tasks outlined in these guidelines local governments can prepare themselves to effectively interact and use expertise from these other groups.

The GIS development cycle starts with the needs assessment where the GIS functions and the geographic data needed are identified. This information is obtained through interviewing potential GIS users. Subsequently, surveys of available hardware, software and data are conducted and, based in the information obtained, detailed GIS development plans are formulated.

It is important to involve potential users in all stages of GIS development. They benefit from this involvement in several ways:

• Describing their needs to the GIS analysts
• Learning what the GIS will be capable of accomplishing for them
• Understanding the nature of the GIS development cycle - the time involved and the costs.

Potential users need to understand that there may be significant time lags between the first steps of Needs Assessment and the time when the GIS can actually be used. Mostly, this is due to the size of the database building task, which can take up to several years in a large jurisdiction.

In addition to understanding that database development takes substantial time, users and managers need to appreciate that GIS is a new technology and its adoption often involves some uncertainty that can cause time delays, on-going restructuring the development program, and the need to resolve unforeseen problems. This set of guideline documents describes the GIS development process in away that will minimize problems, time delays, cost overruns, etc.; however, the occurrence of these situations cannot be completely avoided. The GIS project team and management simply have to be aware that some unforeseen events will happen. GIS development must be viewed as a process rather than a distinct project.

Estimating and planning for the cost of the GIS is a somewhat difficult task. First, it is necessary to recognize that the GIS database will likely be the single most costly item - if a local government develops all of the data itself from maps, etc., this cost can be as much as 70 - 80 % of the total system cost. Thus, acquiring digital data from other GIS systems, government sources or the private sector can be very cost effective. Participating in, or organizing a regional data sharing cooperative or district, can also lead to reduced data costs. When planning for the GIS database, long term data maintenance and retention costs must be estimated as well as the initial start-up costs. Cooperation between agencies with similar data needs may provide the most effective way to achieve long-term data maintenance, retention, and archiving.

7 TASKS FOR GIS DEVELOPMENT AND USE

The GIS development cycle is a set of eleven steps starting with the needs assessment and ending with on-going use and maintenance of the GIS system. These steps are presented here as a logical progression with each step being completed prior to the initiation of the next step. While this view is logical, it is not the way the world always works. Some of the activities in the process may happen concurrently, may be approached in a iterative manner, or may need to be restructured depending on the size and character of the local government conducting the study and the resources available to plan for the GIS. The GIS development cycle is based on the philosophy that one first decides what the GIS should do and then as a second activity decides on how the GIS will accomplish each task. Under this philosophy, the needs are described first, available resources are inventoried second (data, hardware, software, staff, financial resources, etc.), preliminary designs are created and tested as a third major set of activities, and lastly the GIS hardware and software are acquired and the database is built.

Figure 1 - GIS Development Process

Figure 1 shows the GIS development cycle, which is described in terms of 11 major activities. Prior to initiating these studies, the responsible staff in local governments should attend introductory GIS seminars and workshops, GIS conferences, and meetings of specific GIS users' groups, to obtain a broad overview of what GIS is and how others are using these systems.

The 11 steps of the GIS development cycle are:

1. Needs Assessment
2. Conceptual Design of the GIS
3. Survey of Available Data
4. Survey of GIS Hardware and Software
5. Detailed Database Planning and Design
6. Database Construction
7. Pilot Study/Benchmark Test
8. Acquisition of GIS Hardware and Software
9. GIS System Integration
10. GIS Application Development
11. GIS Use and Maintenance

These tasks are one way of dividing up the entire set of activities that must be accomplished to build a successful GIS. While there are other ways of expressing and organizing these activities, this particular structure has been chosen because it emphasizes data development - data definition, data modeling, data documentation, data capture and storage, and data maintenance and retention. The important point to be made here is not the order or structure of the tasks, but rather that, one way or another, all of these tasks must be completed to have a successful GIS.

In some situations, different methods may be more appropriate than those presented in these guides,or a different level of detail may fit the particular situation of a unit of local government. No matter how simple or complex a given GIS environment is, all of the above tasks should be completed at an appropriate level of detail. In the specific guides of this set, examples of different levels of detail will be provided.

The starting point is the needs assessment. It is assumed that the local government has decided that a GIS may be justified and it is reasonable to expend the resources to further study the problem. A final assessment of the costs and benefits will not be made until several tasks have been completed and the nature and size of the resulting GIS can be estimated. In the process presented here, this final feasibility assessment is made as part of the detailed database planning and design activity.

Each of the major portions of the development cycle identified and briefly described below is further described in a subsequent guideline document.

Needs Assessment

The GIS needs assessment is designed to produce two critical pieces of information:

• The list of GIS functions that will be needed
• A master list of geographic data.

These two information sets are extracted from a set of GIS application descriptions, a list of important data,and a description of management processes. Standard forms are used to document the results of user interviews. The information gained in the needs assessment activity goes directly into the Conceptual GIS Design activity.

Conceptual Design of the GIS System

The conceptual design of the GIS system is primarily an exercise in database design. It includes formal modeling (preparation of a data model) of the intended GIS database and the initial stages of the database planning activity. Database planning is the single most important activity in GIS development. It begins with the identification of the needed data and goes on to cover several other activities collectively termed the data life cycle - identification of data in the needs assessment,inclusion of the data in the data model, creation of the meta data, collection and entry of the data into the database, updating and maintenance, and, finally, retention according to the appropriate record retention schedule (Figure 2). A complete data plan facilitates all phases of data collection,maintenance and retention and as everything is considered in advance, data issues do not become major problems that must be addressed after the fact with considerable difficulty and aggravation. The product of the conceptual design activity is a data model which rigorously defines the GIS database and supports the detailed database planning activity.

Figure 2 - Life Cycle of a GIS Database

The conceptual design of the GIS also includes identification of the basic GIS architecture (type of hardware and GIS software), estimates of usage (derived from the Needs Assessment), and scoping the size of the GIS system. All of this is done with reference to the existing data processing environments (legacy systems) that must interface with the GIS. This guideline also includes a section on meta data and data standards.

Survey Of Available Data

A survey of available data can commence once needed data have been identified in the Needs Assessment. This task will inventory and document mapped, tabular and digital data within the local government as well as data available from other sources, such as federal, state, or other local governments and private sector organizations. The entries in this inventory may include other GIS systems within the local area from which some of the needed data may be obtained. If there exists an organized data sharing cooperative or other mechanism for government data sharing, it should be investigated at this time. There also exists the possibility that one or more of the commercial GIS database developers may be able to supply some of the needed data and should therefore be investigated. The documentation prepared at this point will be sufficient to evaluate each potential data source for use in the GIS. Information collected at this point will also form part of the meta data for the resulting GIS database.

Survey Of Available GIS Hardware And Software

Almost all local government GIS programs will rely on commercially available GIS software. As a result, a survey of the available GIS systems needs to be conducted. During this activity, the GIS functionality of each commercial GIS system can be documented for later evaluation.

Detailed Database Design And Planning

The detailed database planning and design task includes the following activities: developing a logical or physical database design based on the data model prepared earlier, evaluating the potential data sources, estimating the quantities of geographic data, estimating the cost of building the GIS database and preparing the data conversion plan. Concurrent with the detailed planning for the database, pilot studies and/or benchmark testing that are desired can be executed. Information gained from these studies and tests will be needed to estimate the size of the equipment (disk space,main memory etc.) and to determine how much application development will be necessary. Subsequently, plans for staffing, staff training, equipment acquisition and installation, and user training must be completed. After the preparation of all these plans, the entire cost of the GIS will be known and the final feasibility assessment can be made.

Pilot Study And Benchmark Tests

Pilot studies and benchmark tests are intended to demonstrate the functionality of the GIS software -simply put, what the commercial GIS from the vendor can do. These tests are useful to demonstrate to potential users and management what the GIS will do for them. Also, performance data of the GIS system can be determined.

GIS Database Construction

Database construction (sometimes referred to as "database conversion") is the process of building the digital database from the source data - maps and tabular files. This process would have been planned during the previous activity and the main emphasis here is management of the activity and quality assurance/quality control of the converted data. The conversion process is often "contracted-out" and involves large quantities of source maps and documents. Close and effective management is the critical factor in successful data conversion.

GIS System Integration

Unlike many other computer applications, a GIS is not a "plug and play" type system. The several components of a GIS must be acquired according to well documented specifications. The database must be created in a careful and organized manner. Once all the individual components have been acquired, they must be integrated and tested. Users must be introduced to the system, trained as necessary, and provided with adequate assistance to begin use of the GIS. Parts of the GIS which may appear to work fine individually may not work properly when put together. The GIS system staff must resolve all the problems before users can access the GIS.

GIS Application Development

"Application" is a general term covering all things that "go on" in a GIS. First, there are "database applications." These are all the functions needed to create, edit, build, and maintain the database,and are usually carried out by the GIS systems staff. Some users may have responsibility for updating selected parts of the GIS database, however the entire database should be under the control of a "database administrator." Other applications are termed "user applications." Contemporary GISs provide many simple applications as part of the initial software package (e.g., map display,query, etc.). More complex applications, or ones unique to a particular user, must be developed using a macro-programming language. Most GISs have a macro-programming language for this purpose (e.g., Arc Macro Language (AML) in ARC/INFO™. and Avenue in ArcView™). The applications needing development by the GIS systems staff will have been described during the Needs Assessment on the GIS Application forms.

GIS System Use And Maintenance

After having described the rather large task of creating a GIS, we can now say that use and maintenance of the GIS and its database will likely require as much attention as was needed to initially build it. Most GIS databases are very dynamic, changing almost daily, and users will immediately think of additional applications that they would like to have developed. Formal procedures for all the maintenance and updating activities need to be created and followed by the GIS system staff and by all users to ensure continued successful operation of the GIS.

8 SUMMARY

This document has presented an overview of the GIS development process, with an emphasis on data and database issues. All of the tasks and issues identified in this document will be described in detail in the remaining eleven guidelines of this series. The procedures are presented as "guides," and not as a "cookbook recipe" which must be rigorously followed. Each of the major tasks in the GIS development process and the information generated within the task should be addressed in any specific project. The methods and forms used in this series can be used, or alternatives can be developed,as appropriate to the situation. The one matter to always keep in mind is that the GIS plan is a document to communicate user needs to a GIS analyst. The components of the plan must contain:

• Descriptions of applications that are understandable to the user
• A logical translation of user requirements to system specifications
• Detailed specification suitable for system development

Following the recommendations in these guidelines cannot, unfortunately, guarantee success. Many of the factors, outside the control of the GIS development team, will affect the ultimate success of the GIS - success being defined as use of the GIS by satisfied users. However, the authors of these guidelines believe that attempting to develop a GIS without following these, or similar procedures, substantially raises the probability of an unsuccessful GIS project - either one that is not useful or one that substantially exceeds both cost and development time estimates.

Finally, although presented here as an independent activity, GIS development must recognize and interface with other computer systems in local government, such as E911, police and fire dispatch, facilities management systems, etc. . The GIS must not be viewed as independent of the other systems, but integrated with them, no matter how difficult, to form a true corporate database for local government.

REFERENCES

1) Fischer, Manfred M. and Nijkamp, Peter, "Geographic Information System, Spatial Modeling, and Policy Evaluation," Berlin & New York: Springer-Verlag, 1993, pg. 42.

2) Abler, R.F., 1987, "The National Science Foundation National Center for Geographic Information and Analysis" International Journal of Geographical Information Systems, 1, no. 4, 303-326.

SUGGESTED READINGS

1. Antenucci, John C., et.al., Geographic Information Systems: A Guide to the Technology, New York: Van Nostrand Reinhold, 1991 (ISBN 0-442-00756-6)

2. Aronoff, Stan, Geographic Information Systems: A Management Perspective, Ottawa: WDL Publications, 1989 (ISBN 0-921804-00-8)

3. Burrough, P.A., Principles of Geographical Information Systems for Land Resources Assessment, Oxford: Oxford University Press, 19865. (ISBN 0-19-854563-0); ISBN 0-19-854592-4 paperback).

4. Huxhold, William E., An Introduction to Urban Geographic Information Systems, Oxford: Oxford University Press, 1991 (ISBN 0-19-506534-4)

5. Korte, George B., A Practitioner's Guide: The GIS Book, Sante Fe: OnWord Press, 1992 (ISBM 0-934605-73-4)

6. Laurini, Robert and Derek Thompson, Fundamentals of Spatial Information Systems, London: Academic Press Limited (ISBN: 0-12-438380-7)

7. Montgomery, Glenn E., and Harold C. Schuck, GIS Data Conversion Handbook, Fort Collins: GIS World, Inc. (ISBN 0-9625063-4-6)

GIS INFORMATION SOURCES

Scholarly journals

There are a number of scholarly journals that deal with GIS. These are published on an on-going basis.

• Cartographica - Contact: Canadian Cartographic Association
• Cartography and Geographic Information Systems - Contact: American Cartographic Association
• International Journal of Geographical Information Systems - Contact: Keith Clark at CUNY Hunter College, New York City
• URISA Journal - Contact: Urban and Regional Information Systems Association

Trade magazines

There are a number of trade magazines that are focused on GIS. They are:

• GIS World

  GIS World Inc. 155 E. Boardwalk Drive Suite 250, Fort Collins, CO 80525. Phone: 303-223-4848 Fax: 303-223-5700 Internet: info@gisworld.com

• Business Geographics

GIS World, Inc. 155 E. Boardwalk Drive, Suite 250 Fort Collins, CO 80525. Phone: 303-223-4848 Fax: 303-223-5700. Internet: info@gisworld.com

• Geo Info Systems

Advanstar Communications 859 Williamette St. Eugene, OR., 97401-6806 Phone: 541-343-1200 Fax: 541-344-3514 Internet:geoinfomag@aol.com, WWW site:http://www.advanstar.com/geo/gis

• GPS World

Advanstar Communications 859 Williamette St. Eugene, OR., 97401-6806 Phone: 541-343-1200 Fax: 541-344-3514 Internet:geoinfomag@aol.com, WWW site:http://www.advanstar.com/geo/gis

Conference Proceedings

• American Congress on Surveying and Mapping (ACSM)

5410 Grosvenor Lane Bethesda, MD, 20814 Phone: 301-493-0200 Fax: 301-493-8245

• American Society for Photogrammetry and Remote Sensing (ASPRS) & (GIS/LIS)

5410 Grosvenor Lane Bethesda, MD, 20814 Phone: 301-493-0290 Fax: 301-493-0208

• Association of American Geographers (AAG)

1710 Sixteenth St. N.W. Washington D.C., 20009-3198 Phone: 202-234-1450 Fax: 202-234-2744

• Automated Mapping/Facility Management International (AM/FM International)

14456 East Evans Ave. Aurora, CO, 80014 Phone: 303-337-0513 Fax: 303-337-1001

• Canadian Association of Geographers (CAG)

Burnside Hall, McGill University Rue Sherbrooke St. W Montreal, Quebec H3A 2K6 Phone: 514-398-4946 Fax: 514-398-7437

• Canadian Institute of Geomatics (CIG)

206-1750 rue Courtwood Crescent Ottawa, Ontario, K2C 2B5 Phone: 613-224-9851 Fax: 613-224-9577

• Urban And Regional Information Systems Association (URISA)

900 Second St. N.E., Suite 304 Washington, D.C. 20002 Phone: 202-289-1685 Fax: 202-842-1850

Glossary

Accuracy - Degree of conformity with a standard, or the degree of correctness attained in a measurement. Accuracy relates to the quality of a result. If accuracy is relative, the position of a point is defined in relation to another point. It is less expensive to build a GIS in the context of relative accuracy. If accuracy is absolute, the position of a point is defined by a coordinate system. Building a GIS in the context of absolute accuracy requires use of the global positioning system.

Accuracy Requirement - statement of how precise the desired results must be to support a particular application.

Adjoining Sheets - Maps that are adjacent to one another at the corners and on one or more sides.

Aerial - Relating to the air atmosphere, being applicable in a descriptive sense to anything in space above the ground and within the atmosphere.

Aerial Photography - The method of taking photographs from an aerial platform (aircraft). (1.) Vertical photography, some times called orthophotography (see entry) is used for photogrammetric mapping and requires a high degree of accuracy. (2.) Oblique photography is used for general information, sometimes to verify certain attributes, but does not provide accurate measurements for photogrammetric mapping.

Aerial Survey - A survey utilizing aerial photography or from remote sensing technology using other bands of the electromagnetic spectrum such as infrared, gamma or ultraviolet.

Algorithm - A set of instructions; ordered mathematical steps for solving a problem like the instructions in a computer program.

Alignment - Relates to survey data transposed to maps. The correct position of a line or feature in relation to other lines or features. Also the correct placement of points along a straight line.

Alphanumeric - A combination of alphabetic letters, numbers and or special characters. A mailing address is an alphanumeric listing.

Analog Data - Data represented in a continuous form, not readable by a computer.

Area - level of spatial measurement referring to a two-dimensional defined space; for example, a polygon on the earth as projected onto a horizontal plane.

Attribute - 1. A numeric, text, or image data field in a relational data base table that describes a spatial feature such as a point, line, node, area or cell. 2. A characteristic of a geographic feature described by numbers or characters, typically stored in tabular format, and linked to the feature by an identifier. For example, attributes of a well (represented by a point) might include depth, pump type, location, and gallons per minute.

AM/FM - Automated mapping/facilities management. A GIS designed primarily for engineering and utility purposes, AM/FM is a system that manages databases related to spatially distributed facilities.

Base Data - set of information that provides a baseline orientation for another layer of primary focus, e.g., roads, streams, and other data typically found on USGS topographic and/or planimetric maps.

Base Line - A surveyed line established with more than usual care upon which surveys are based.

Base Map - A map showing planimetric, topographic, geological, political, and/or cadastral information that may appear in many different types of maps. The base map information is drawn with other types of changing thematic information. Base map information may be as simple as major political boundaries, major hydrographic data, or major roads. The changing thematic information may be bus routes, population distribution, or caribou migration routes.

Base Station - a GPS receiver on a known location that may broadcast and/or collect correction information for GPS receivers on unknown locations.

Bench Mark - A relatively permanent point whose elevation above or below an adopted datum is known.

Beta Test - Hardware or software testing performed by users in a normal operating environment; follows alpha testing, which is generally done in the developer's facility.

Bezier - (computer graphics) A curve generated by a mathematical formula in CAD (see entry) programs that maintains continuity with other Bezier curves.

Binary - The fundamental principal behind digital computers. Binary means two, computer input is converted into binary numbers made up of O and 1 (see bit).

BIT: (computers) a binary digit with a value of either 1 or 0.

Block (Tax) - A group of municipal tax lots that can be isolated from other parcels by a boundary, usually a roadway, waterway or properly labeled lot line.

Boundary Line - A line along which two areas meet. In specific cases, the word "boundary" is sometimes omitted, as in "state line", sometimes the word "line" is omitted, as in "international boundary", "county boundary", etc. The term "boundary line" is usually applied to boundaries between political territories, as "state boundary line", between two states. A boundary line between privately owned parcels of land is termed a property line by preference, or if a line of the United States public land surveys, is given the particular designation of that survey system, as section line, township line, etc.

BPS - Bits per second, the speed of data transfer.

Buffer A zone of a given distance around a physical entity such as a point, line, or polygon.

CAD/CADD - (Computers) Computer-Aided Design/ Computer-Aided Design and Drafting. Any system for Computer-Aided rather than manual drafting and design. Displays data spatially. on a predefined coordinate grid system, allowing data from different sources to be connected and referenced by location. Speeds conventional map development process by 1. permitting replication of shapes, floor plans, etc. from an electric library rather than requiring every component to be drawn from scratch. 2. Plotters and terminal screens are faster and more accurate than manual drafting. 3. Portions of drawings can be edited, enlarged, etc. quickly. 4. Related information can be stored in files and added to drawings in layers.

CAD - (Communication) Computer-Aided Dispatching. Used with emergency vehicles, CAD can be very sophisticated. Online maps of a city can display emergency vehicles as moving dots on the map, their status (enroute to an emergency, awaiting a call, call completed, returning to base, etc.) indicated by different colors. (The acronym for computer-aided dispatch is sometimes confused with computer-aided design.)

Cadastre - a record of interests in land, encompassing both the nature and extent of interests. Generally, this means maps and other descriptions of land parcels as well as the identification of who owns certain legal rights to the land (such as ownership, liens, easements, mortgages, and other legal interests). Cadastral information often includes other descriptive information about land parcels.

Cadastral - Relating to the value, extent and ownership of land for tax purposes. Cadastral maps describe and record ownership. Also called property map.

Cadastral Survey - A survey relating to land boundaries and subdivisions, made to create units suitable for transfer or to define the limitations to title. Derived from "cadastre", and meaning register of the real property of a political subdivision with details of area, ownership, and value. The term cadastral survey is now used to designate the surveys for the identification and resurveys for the restoration of property lines; the term can also be applied properly to corresponding surveys outside the public lands, although such surveys are usually termed land surveys through preference. See also boundary, survey.

Cartographic (Planimetric) Features - Objects like trees or buildings shown on a map or chart.

Cartography - The technology of mapping or charting features of Earth's topography.

Centroid - The "center of gravity" or mathematically exact center of an irregular shaped polygon; often given as an x, y coordinate of a parcel of land.

Clearinghouse - a physical repository structure used to accumulate and disseminate digital data and information concerning that data. In the GIS context a clearinghouse can contain all or a portion of spatial, meta data and informational data.

Client - A software application that works on your behalf to extract some service from a server somewhere on the network. Basic idea, think of your telephone as a client and the telephone company as a server.

COGO - Acronym for Coordinate Geometry achieved via a computer program.

Computer-aided Design or Drafting (CAD) - A group of computer software packages for creating graphic documents.

Control Point - A point in a network, identifiable in data or a photograph, with a given horizontal position and a known surface elevation. It is correlated with data in data set or photograph.

Contour - An imaginary outline of points on the ground which are at the same altitude relative to mean sea level.

Contour Line - A line on a map or chart that connects to points which are at the same elevation.

Contour Map - A map that defines topography (hypsography) by interpreting contour lines as relief.

Control - Also called ground control. A system of survey marks or objects called control points that have established positions and/or elevations verified by ground survey. The marks, or control points, serve as a reference correlating other data such as contour lines (see entry) determined from aerial surveys.

Conversion - 1. The translation of data from one format to another (e.g., TIGER to DXF; a map to digital files).S 2. Data conversion when transferring data from one system to another (E.g., SUN to IBM).s

Coordinate - The position of point is space in respect to a Cartesian coordinate system (x, y and/or z values). In GIS, a coordinate often represents locations on the earth's surface relative to other locations.

Coordinate System - The system used to measure horizontal and vertical distances on a planimetric map. In a GIS, it is the system whose units and characteristics are defined by a map projection. A common coordinate system is used to spatially register geographic data for the same area. See map projection

CRT - Cathode Ray Tube. A computer screen or monitor.

CTG - Center for Technology in Government

Data Capture - series of operations required to encode data in a computer-readable digital form (digitizing, scanning, etc.)

Data Dictionary - description of the information contained in a data base, e.g., format, definition, structure, and usage. It typically describes and defines the data elements of the data base and their interrelationships within the larger context of the data base.

Data Element - specific item of information appearing in a set of data, e.g. well site locations.

Data Model 1. A generalized, user-defined view of the data related to applications. 2. A formal method for arranging data to mimic the behavior of the real world entities they represent. Fully developed data models describe data types, integrity rules for the data types, and operations on the data types. Some data models are triangulated irregular networks, images, and georelational or relational models for tabular data.

Data Quality - refers to the degree of excellence exhibited by the data in relation to the portrayal of the actual phenomena

Data Sets - a collection of values that all pertain to a single subject.

Data Standardization - the process of achieving agreement on data definitions, representation, and structures to which all data layers and elements in an organization must conform.

Data Structure - organization of data, particularly the reference linkages among data elements.

Database -usually a computerized file or series of files of information, maps, diagrams, listings, location records, abstracts, or references on a particular subject or subjects organized by data sets and governed by a scheme of organization. "Hierarchical" and relational" define two popular structural schemes in use in a GIS. For example, a GIS database includes data about the spatial location and shape of geographic entities as well as their attributes.

Database Management System (DBMS) - 1. The software for managing and manipulating the whole GIS including the graphic and tabular data. 2. Often used to describe the software for managing (e.g., input, verify, store, retrieve, query, and manipulate) the tabular information. Many GlSs use a DBMS made by another software vendor, and the GIS interfaces with that software.

Datum - a mathematical reference framework for geodetic coordinates defined by the latitude and longitude of an initial point, the azimuth of a line from this point, and the parameters of the ellipsoid upon which the initial point is located.

DEC - Department of Environmental Conservation

Differential Correction - the method (usually done through post processing) of using two GPS receivers, one on a known location and one on an unknown location, using information from the one on the known location to correct the position of the unknown location.

Digital Accuracy - refers to the accuracy of digital spatial data capture.

Digital Elevation Model (DEM) - a file with terrain elevations recorded at the intersections of a fine grid and organized by quadrangle to be the digital equivalent of the elevation data on a topographic base map.

Digital Data - a form of representation in which distinct objects, or digits, are used to stand for something in the real world--temperature or time--so that counting and other operations can be performed precisely. Data represented digitally can be manipulated to produce a calculation, a sort, or some other computation. In digital electronic computers, two electrical states correspond to the Is and Os of binary numbers, which are manipulated by computer programs.

Digital Exchange Format (DXF) 1. ASCII text files defined by Autodesk, Inc. (Sausalito, CA) at first for CAD, now showing up in third-party GIS software . 5 2. An intermediate file format for exchanging data from one software package to another, neither of which has a direct translation for the other but where both can read and convert DXF data files into their format. This often saves time and preserves accuracy of the data by not reautomating the original.

Digital Line Graph (DLG) 1. In reference to data, the geographic and tabular data files obtained from the USGS for exchange of cartographic and associated tabular data files. Many non-DLG data may be formatted in DLG format. 2. In reference to data, the formal standards developed and published by the USGS for exchange of cartographic and associated tabular data files. Many non-DLG data may be formatted in DLG format.

Digital Map - A machine-readable representation of a geographic phenomenon stored for display or analysis by a digital computer; contrast with analog map.

Digital Orthophoto - A geographically correct digital image with the same accuracy as a vector digital map, but preserving the information content of the original photography.

Digital Orthophoto Quarter-Quad (DOQ) - a 3.75 minute square distortion free image of the surface of the earth. The imagery has been geographically and photographically rectified to remove all distortion, and meet requirements of the USGS.

Digital Terrain Model (DTM) - A computer graphics software technique for converting point elevation data into a terrain model displaced as a contour map, sometimes as a three-dimensional "hill and valley" grid view of the ground surface.

Digitize - A means of converting or encoding map data that are represented in analog form into digital information of x and y coordinates.

Digitized Terrain Data - Transposed elevation information from maps or photographs to X-Y-Z digital coordinates for storage on magnetic media.

Digitizer - A device used to capture planar coordinate data, usually as x and y coordinates, from existing analog maps for digital use within a computerized program such as a GIS; Also called a digitizing table.

Digitizing - refers to the process of manually converting an analog image or map or other graphic overlay into numerical format for use by a computer with the use of a digitizing table or tablet and tracing the input data with a cursor (see also scanning).

DIME - Dual Independent Map Encoding Provides vector data such as streets to census data addresses. Superseded by Topologically Integrated Geographic Encoding and Referencing (see TIGER).

DIME File - A geographic base file produced by the U.S. Census Bureau with Dual Independent Map Encoding. Now being superseded by TIGER files (see below).

DLG - See Digital Line Graph

DOB - Division of the Budget

DOQ - See Digital Orthophoto Quarter-quad

DOT - Department of Transportation

DTF - Department of Taxation and Finance

Edge Match - An editing procedure to ensure that all features crossing adjacent map sheets have the same edge locations, attribute descriptions, and feature classes.

Federal Information Processing Standards (FIPS) - official source within the federal government for information processing standards. They were developed by the Institute for Computer Sciences and Technology, at the National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards.

Federal Geographic Data Committee (FGDC) - established by the Federal Office of Management and Budget, is responsible for the coordination of development, use, sharing, and dissemination of surveying, mapping, and related spatial data.

Fifth Generation Computer - A computer designed for applications of artificial intelligence (Al). Some elements of spatial data management, especially the CADD output side, are beginning to integrate Al computing.

FOIL - Freedom of Information Law

Format - 1. The pattern in which data are systematically arranged for use on a computer. 2. A file format is the specific design of how information is organized in the file. For example, DLG, DEM, and TIGER are geographic data sets in particular formats that are available for many parts of the United States 6

File Transfer Protocol (FTP) - a standard protocol that defines how to transfer files from one computer to another.

FORTRAN - A high-level programming language and compiler originally designed to express math formulas. Developed in 1954 by IBM it is still the most widely used language for scientific and engineering programming.

BF/DIME - See Geographic base file/dual independent map encoding

Geocode - The process of identifying a location as one or more x, y coordinates from another location description such as an address. For example, an address for a student can be matched against a TIGER street network to locate the student's home.

Geodetic Monumentation - a permanent structure that marks the location of a point taking into account the earth's curvature.

Geographic - Pertains to the study of the Earth and the locations of living things, humans and their effects.

Geographic Base File/dual Independent Map Encoding (GBF/DIME) - A data exchange format developed by the US Census Bureau to convey information about block-face/street address ranges related to 1980 census tracts. These files provide a schematic map of a city's streets, address ranges, and geostatistical codes relating to the Census Bureau's tabular statistical data. See also TIGER, created for the 1990 census.

Geographic Database - Efficiently stored and organized spatial data and possibly related descriptive data.

Geographic Information Retrieval and Analysis (GIRAS) - Data files from the US Geological survey. GIRAS files contain information for areas in the continental United States, including attributes for land use, land cover, political units, hydrologic units, census and county subdivisions, federal land ownership, and state land ownership. These data sets are available to the public in both analog and digital form.

Geographic Information System (GIS) - An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information. Certain complex spatial operations are possible with a GIS that would be very difficult, time-consuming, or impractical otherwise.

Geographic Object - A user-defined geographic phenomenon that can be modeled or represented using geographic data sets. Examples include streets, sewer lines, manhole covers, accidents, lot lines, and parcels.

Geographical Resource Analysis Support System (GRASS) - 1. A public-domain raster GIS modeling product of the US Army Corps of Engineers Construction Engineering Research Laboratory. 2. A raster data format that can be used as an exchange format between two GlSs.

Georectify - the process of referencing points on an image to the real world coordinates.

Georeference - To establish the relationship between page coordinates on a paper map or manuscript and known real-world coordinates

Geospatial - a term used to describe a class of data that has a geographic or spatial nature.

Geostationary Satellite: An earth satellite that remains in fixed position in sync with the earth's rotation.

GIS - Geographic information system. A computer system of hardware and software that integrates graphics with databases and allows for display, analysis, and modeling.

Grid-Cell Data - Grid-cell data entry places a uniform grid over a map area, and the area within the cell is labeled with one attribute or characteristic, such as elevation averaged over all points. Grid cells can be layered with differing types of information.

Global Positioning System (GPS) - a system developed by the U.S. Department of Defense based on 24 satellites orbiting the Earth. Inexpensive GPS receivers can accurately determine ones position on the Earth's surface.

Ground Truth - Information collected from a survey area as remote sensing data is being collected from the same area (see control).

Hierarchical - A way of classifying data, starting with the general and going to specific labels.

Hydrography - Topography pertaining to water and drainage feature.

Hypsography - 1 ) The science or art of describing elevations of land surfaces with reference to a datum, usually sea level. 2) That part of topography dealing with relief or elevation of terrain.

Image - A graphic representation or description of an object that is typically produced by an optical or electronic device. Common examples include remotely sensed data such as satellite data, scanned data, and photographs. An image is stored as a raster data set of binary or integer values representing the intensity of reflected light, heat, or another range of values on the electromagnetic spectrum. Remotely sensed images are digital representations of the earth.

Imagery - a two dimensional digital representation of the earth's surface. Examples are a digital aerial photograph, a satellite scene, or an airborne radar scan.

Index - A specialized lookup table or structure within a database and used by an RDBMS or GIS to speed searches for tabular or geographic data.

Infrastructure - The fabric of human improvements to natural settings that permits a community, neighborhood, town, city metropolis, region, state, etc., to function.

Initial Graphics Exchange Specification (IGES) An interim standard format for exchanging graphics Polygon data among computer systems.

Internet - a system of linked computer networks, worldwide in scope, that facilitates data communication services such as remote login, file transfer, electronic mail, and newsgroups. The Internet is a way of connecting existing computer networks that greatly extends the reach of each participating system.

Internet Protocol (IP) - the most important of the protocols on which the Internet is based. It allows a packet to traverse multiple networks on the way to its final destination.

Interpolate - Applied to logical contouring by determining vertical distances between given spot elevations.

IT - Information Technology

Land Information System (LIS) - the sum of all the elements that systematically make information about land available to users including: the data, products, services, the operating procedures, equipment, software, and people.

Land Information System (LIS) - NJ State 45:8-28(e) - Any computer coded spatial database designed for multi-purpose public use developed from or based on property boundaries.

Latitude - The north-south measurement parallel to the equator.

Layer- A logical set of thematic data, usually organized by subject matter.

Layers - refers to the various "overlays" of data each of which normally deals with one thematic topic. These overlays are registered to each other by the common coordinate system of the database.

Longitude - The angular distance, measured in degrees, cast or west from the Greenwich meridian, or by the difference in time between two reference meridians on a globe or sphere.

Lot Number - A numerical parcel designation, that when combined with a block number is unique to a single parcel of land within a given municipality.

Manual Digitizing - Conversion of an analog measurement into a digital form by using a manual device such as a calculator.

Map - A representation of a portion of the earth, usually drawn on a flat surface. (From Latin mappa, a napkin, sheet or cloth upon which maps were drawn.)

Map Projection - A mathematical model for converting locations on the earth's surface from spherical to planar coordinates, allowing flat maps to depict three dimensional features. Some map projections preserve the integrity of shape; others preserve accuracy of area, distance, or direction.

Map Units - The coordinate units in which the geographic data are stored, such as inches, feet, or meters or degrees, minutes and seconds.

Metadata - data describing a GIS database or data set including, but not limited to, a description of a data transfer mediums, format, and contents, source lineage data, and any other applicable data processing algorithms or procedures .

NCGIA - National Center for Geographic Information Analysis

Network Analysis - Addresses relationships between locations on a network. Used to calculate optimal routes, and optimal locations for facilities.

NSGIC - National States Geographic Information Council

NSDI - National Spatial Data Infrastructure

OPRHP - Office of Parks, Recreation and Historical Preservation

ORPS - Office of Real Property Services

Orthophoto - A photograph of the earth's surface in which geographic distortion has been removed.

Overlay - A layer of data representing one aspect of related information.

Parcel - Generally refers to a piece of land that can be designated by number.

Photogrammetry - The system of gathering information about physical objects through aerial photography and satellite imagery.

Plane-Coordinate System A system for determining location in which two groups of straight lines intersect at right angles and have as a point of origin a selected perpendicular intersection.

Planimetric Map - A map which presents the horizontal positions only for the features represented; distinguished from a topographic map by the omission of relief in measurable form. The natural features usually shown on a planimetric map include rivers, lakes and seas; mountains, valleys and plains; and forests, prairies, marshes and deserts. The culture features include cities, farms, transportation routes and public-utility facilities; and political and private boundary lines. A planimetric map intended for special use may present only those features which are essential to the purpose to be served.

Plat: A scale diagram void of cultural, drainage and relief features, showing only land boundaries and subdivisions together with data essential to its legal description.

Plotter - Equipment that can plot a graphic file using multiple line weights and colors. Types available today are: pen, laser, and electrostatic plotters.

Point Data - level of spatial definition referring to an object that has no dimension, e.g., well or weather station.

Points - Items such as oil wells, utility poles, etc. Specific objects with exact location noted.

Polygon - A vector representation of an enclosed region, described by a sequential list of vertices or mathematical functions.

Positional Accuracy - term used in evaluating the overall reliability of the positions of cartographic features relative to their true position.

Precision - refers to the quality of the operation by which the result is obtained, as distinguished from accuracy.

Protocol - a definition for how computers will perform when talking to each other. Protocol definitions range from how bits are placed on a wire to the format of an electronic mail message. Standard protocols allow computers from different manufacturers to communicate; the computers can use completely different software, providing that the programs running on both ends agree on what the data means.

Quadrangle - A four-sided region, usually bounded by a pair of meridians and a pair of parallels.

Quality Control - process of taking steps to ensure the quality of data or operations is in keeping with standards set for the system.

Raster - A grid-type data format used to interpret gray-scale photographs and satellite imagery. Imagery is stored as dots or pixels, each with a different shade or density.

Raster Data - Machine-readable data that represent values usually stored for maps or images and organized sequentially by rows and columns. Each "cell" must be rectangular but not necessarily square, as with grid data.

RDBMS - See relational database management systems.

Rectified - referencing points, lines, and/or features of two dimensional images to real world geographic coordinates, to correct distortion in the image.

Rectify - The process by which an image or grid is converted from image coordinates to real-world coordinates. Rectification typically involves rotation and scaling of grid cells, and thus requires resampling of values.

Registration - the procedure used to bring two maps or data layers into concurrence via known ground location control points or the procedure of bringing a map or data layers into concurrence with the earth's surface.

Relational Database Management System (RDBMS) - A database management system with the ability to access data organized in tabular files that may be related together by common field (item). An RDBMS has the capability to recombine the data items from different files, thus providing powerful tools for data usage.

Remote Sensing - Recording imagery or data and information from a distance. Photography is a form of remote sensing. Satellites provide a remote sensing platform for developing geology and soils analysis with sensors sensitive to various bands of the electromagnetic spectrum.

Resolution - 1. The accuracy at which the location and shape of map features can be depicted for a given map scale. For example, at a map scale of 1:63,360 (1 inch=1 mile), it is difficult to represent areas smaller than 1/10 of a mile wide or 1/10 of a mile in length because they are only 1/1 0-inch wide or long on the map. In a larger scale map, there is less reduction, so feature resolution more closely matches real world features. As map scale decreases, resolution also diminishes because feature boundaries must be smoothed, simplified, or not shown at all. 2. The size of the smallest feature that can be represented in a surface. 3. The number of points in x and y in a grid (e.g., the resolution of a USGS one-degree DEM is 1.201 x 1.201 mesh points).2

Rubber-sheet - A procedure to adjust the entities of a geographic data set in a non-uniform manner. From- and to- coordinates are used to define the adjustment.

SARA - State Archives and Records Administration

Scale - the relationship between a distance on a map and the corresponding distance on the earth. Often used in the form I :24,000, which means that one unit of measurement on the map equals 24,000 of the same units on the earth's surface.

Scanner - A scanner is an optical device that recognizes dark and light dots on a surface and converts this recognition into a digital file. However, scanners generally do not create a map database in a logically correct format, so additional computer-aided manipulation and often manual editing are used to add intelligence required by a specific GIS platform.

Scanning - Also referred to as automated digitizing or scan digitizing. A process by which information originally in hard copy format (paper print, mylar transparencies, microfilm aperture cards) can be rapidly converted to digital raster form (pixels) using optical readers.

Schematic Map - A map prepared by electronically scanning or digitizing in which the lines are not dimensionally or positionally accurate.

SDTS - Spatial Data Transfer Standard

SED - State Education Department

SEMO - State Emergency Management Office

Server - software that allows a computer to offer a service to another computer. Other computers contact the server program by means of matching client software. Also a computer using server software.

Source Material - data of any type required for the production of mapping, charting, and geodesy products including, but not limited to, ground-control aerial and terrestrial photographs, sketches, maps, and charts; topographic, hydrographic, hypsographic, magnetic, geodetic, oceanographic, and meteorological information; intelligence documents; and written reports pertaining to natural and human-made features.

Spatial Data - data pertaining to the location of geographical entities together with their spatial dimensions. Spatial data are classified as point, line, area, or surface.

Spatial Index - A means of accelerating the drawing, spatial selection, and entity identification by generating geographic-based indexes. Usually based on an internal sequential numbering system

Spatial Model - Analytical procedures applied with a GIS. There are three categories of spatial modeling functions that can be applied to geographic data objects within a GIS: (1) geometric models (such as calculation of Euclidian distance between objects, buffer generation area, and perimeter calculation); (2) coincidence models (such as a polygon overlay); and (3) adjacency models (pathfinding, redistricting, and allocation). All three model categories support operations on geographic data objects such as points, lines, polygons, TlNs, and grids. Functions are organized in a sequence of steps to derive the desired information for analysis.

Stakeholders - Any constituency in the environment that is affected by an organization's decisions and policies.

Standards - In computing, a set of rules or specifications which, taken together, define the architecture of a hardware device, program, or operating system.

State Plane Coordinate System - The plane-rectangular coordinate systems established by the United States Coast and Geodetic Survey (now known as National Ocean Survey), one for each state in the United States, for use in defining positions of geodetic stations in terms of plane-rectangular (X and Y) coordinates. Each state is covered by one or more zones, over each of which is placed a grid imposed upon a conformal map projection. The relationship between the grid and the map projection is established by mathematical analysis. Zones of limited east-west dimension and indefinite north south extent have the transverse Mercator map projection as the base for the state coordinate system, whereas zones for which the above order of magnitude is reversed have the Lambert conformal conic map projection with two standard parallels. For a zone having a width of 158 statute miles, the greatest departure from exact scale (scale error) is 1 part in 10,000. Only adjusted positions on the North American datum of 1927 and NAD 1983 may be properly transformed into plane coordinates on a state system. All such geodetic positions which are determined by the National Ocean Survey are transformed into state plane-rectangular coordinates on the proper grid, and are distributed by that bureau with the geodetic positions. State plane coordinates are extensively used in recording land surveys. and in many states such use has received approval by legislative enactment.

SUNY - State University of New York

System - A group of related or interdependent elements that function as a unit.

Tax Map - An accurate map of a municipal territory prepared for the purpose of taxation. Showing among other things, the location and width of streets, roads, avenues and each individual lot of land within the municipality.

Text Data - Information in a GIS system such as property owners' names and lot dimensions.

Thematic Layer - mapping categories, consisting of a single type of data such as population, water quality, or timber stands, intended to be used with base data.

Thematic Map A map that illustrates one subject or topic either quantitatively or qualitatively.

Theme - A collection of logically organized geographic objects defined by the user. Examples include streets, wells, soils, and streams.

TIGER - supersedes DIME (see entry) files.

TIGER - See Topologically Integrated Geographic Encoding and Referencing

Topographic Map - A map of land-source features including drainage lines, roads, landmarks, and usually relief, or elevation.

Topologically Integrated Geographic Encoding and Referencing data (TIGER) - A format used by the US Census Bureau to support census programs and surveys. It is being used for the 1990 census. TIGER files contain street address ranges along lines and census tract/block boundaries. These descriptive data can be used to associate address information and census/demographic data to coverage features.

Topology - The spatial relationships between connecting or adjacent coverage features (e.g., arcs, nodes, polygons, and points). For example, the topology of an arc includes its from- and to- nodes and its left and right polygons. Topological relationships are built from simple elements into complex elements: points (simplest elements), arcs (sets of connected points), areas (sets of connected arcs), and routes (sets of sections) that are arcs or portions of arcs). Redundant data (coordinates) are eliminated because an arc may represent a linear feature, part of the boundary of an area feature, or both. Topology is useful in GIS because many spatial modeling operations don't require coordinates, only topological information. For example, to find an optimal path between two points requires a list of which arcs connect to each other and the cost of traversing along each arc in each direction. Coordinates are only necessary to draw the path after it is calculated .

Transformation - The process of converting data from one coordinate system to another through translation, rotation, and scaling .

Transmission Control Protocol (TCP) - One of the protocols on which the Internet is based.

Vectors - Lines defined by "x", "y" and "z" coordinate endpoints. Roads, rivers, contour lines, etc. presented as vector lines.

Vector Data - A coordinate-based data structure commonly used to represent map features. Each linear feature is represented as a list of ordered x, y coordinates. Attributes are associated with the feature (as opposed to a raster data structure, which associates attributes with a grid cell). Traditional vector data structures include double-digitized polygons and arc-node models.

Vector Display: A vector display on a computer screen is produced by drawing vectors on the screen. A raster display, in contrast, is produced on a screen as rows of dots of "on" or "off' which produce the picture.

Wide Area Network (WAN) - a network that uses high-speed, long distance communications networks or satellites to connect computers over distances greater than those traversed by local area networks (LANs)--about 2 miles.

Workstations and Terminals A workstation is a device or a combination of devices integrated to provide the user with graphic data entry, display, and manipulation. These devices are used for map digitizing and map-related applications, geographic analysis and ad hoc query. Most systems still use some type of inexpensive edit-query workstations or terminals to provide low-cost access to both maps and related data.

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