Geographical Information Systems

Geog 481/506                                                                                                  Tu Th 3:30-4:50pm
Fall 2011                                                                                                          Fillmore 170

Instructor: Ling Bian                                                                                          LabA: Tue:   5-6:20pm, W145, Chunyuan diao
Office: 120 Wilkeson                                                                                        LabB: Thur:  6:30-7:50pm, W145, Tong Sun
Office hours: Tu Th 2-3pm  or by appt.                                                             LabC: Fri:  10-11:20am, W145, Tong Sun

TIGER

1. Street unit

            Street segment
                A street segment is defined as the range of addresses that run along a street from one intersection to the next intersection

            Address range
                An address range is the range between the lowest possible house number at one intersection
                and the highest possible house number at the other intersection
 

2. Census units

(1) Census tracts
        Defined by the U.S. Census Bureau for statistical reporting of demographic, economic, and other data
        The boundaries follow major streets or natural features
        The boundaries are so established that population in each tract is approximately 4,000 regardless of its size
        Census tracts are numbered consecutively and unique within the jurisdiction

(2) Block groups

        Comprise a population of approximately 1,500
        Boundaries coterminous with census tract boundaries

(3) Blocks

                    Smallest geographic area formed by street segments
                    Coded by a 4-digit number, the first one represents the block group, and the last three are consecutive and unique within a block group

 

3. GBF/DIME files
            Geographic Base Files (GBF)
            Dual Independent Map Encoding System (DIME)
 

4. Topologically Integrated Geographic Encoding and Referencing files (TIGER)

            Developed by the U.S. Census Bureau for 1990 census
            The spatial and attribute processes were combined into one system
            A single seamless data set that cover the entire country
            Topologically structured

        Geographic features
            DIME and 1:100,000 Digital Line graph
            Geographic coordinate system
            Geographic area code
            Roads, utility lines, etc.
            Attributes for spatial features and other attributes
            Block contains aggregated information

5. Applications of TIGER data
            Address matching, network analysis, district delineation
 

6. Reading: chpt 3.