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

GIS Analysis Functions

5. Integrated analysis of spatial and attribute data

 (3) Neighborhood operations
    Assigning attributes to a target location according to the evaluation
    of neighborhood characteristics

            Three basic parameters:

                        One or more targets
                        A neighborhood around each target
                        A function performed within the neighborhood

            Neighborhood geometry

 

            Evaluation functions

                        Average, maximum, minimum, diversity, majority, etc.

            Moving window approach

A function is executed for successive windows. Result of
execution is written to the target cell.

(4) Point in polygon and Line in polygon
 

(5) Topographic functions

            Topographic functions
            The calculation of topographic value at a specific location or in the vicinity

            Elevation

Slope angle: rate of change in elevation, by degree of arc or by % slope

            Slope aspect: the direction that a surface faces

 

(6) Spatial interpolation

Predict the unknown value at a location using the known values at surrounding area.
            Linear interpolation
            Thiessen polygon
            Inverse distance
            Trend surface
            Fourier series
            Kriging

(7) Proximity analysis (Buffering)

            The identification of a zone of interest around an entity or a set of entities.

(8) Network analysis

            A network is a set of interconnected lines making up a set of features
            through which resources can flow.

            The shortest path problem

            An evaluation of links and turns required to traverse a network between
             required stops.

            The traveling salesperson problem

            An evaluation of best sequence to visit each of a set of stops and the best
            route between the stops.

            Location-allocation

            A match between supply and demand involving the movement of people, goods,
            information, and services.

(9) Spread functions

            An evaluation of phenomena that accumulate with distance. It calculates the
            running total of a variable at each step when moving outwards at all directions
            from one ore more starting points, and writes the running total to an accumulation file.

            Friction surface

            Terrain trafficability

(10) Stream functions

A directed search outward, step by step, from a starting point based on a set of decision
rules. The procedure stops when he rules are violated. The output is a trace of paths.

(11) Viewshed analysis

            The delineation of areas that are viewable from a point.

            Source data

            Viewing parameters
                        Maximum viewable line-of-sight distance
                        Location of viewing point
                        Vertical and horizontal angle of view
                        Viewing direction

(12) Illumination and perspective view


 

 6. Reading: Chpt 5,6,9,10