1. Geographic Information Systems
GIS Analysis and Modeling

2. 6. Topographic Functions
- The calculation of topographic value at a specific location or in the vicinity

3. 6. Topographic Functions ..
Elevation
Slope angle
- rate of change in elevation, by degree of arc or by % slope
Slope aspect
- the direction that a surface faces

5. 6. Topographic Functions ..
Perspective view
- Creates a 3-D block diagram showing how surface appears from a defined position
- Is useful in showing the 3-D context of features on a surface, such as a natural landscape

6. 3-D Perspective

7. Bowling Green
Z=10
J. Yan, SUNY Buffalo

8. J. Yan, SUNY Buffalo

9. A. Toy, SUNY BUffalo

10. TINs

11. Color infrared composite of the IKONOS draped over the DEM as viewed from the west side of the study area to the east from an elevation of 10,000 m, Xichang, China Xu, University of Utah, Gong, UC-Berkeley

12. Fisher, Erich , D GIS archaeology in South Africa: archeologists working along the South African southern coast use multidimensional GIS applications to model Pleistocene caves and paleo-environments reconstructing the landscape CA. 420,000 to 30,000 BP. GEO:connexion, 4 (5): 40

13. 7. Neighborhood Operations
Assigning attributes to a target location according to the evaluation of neighborhood characteristics

14. 7. Neighborhood Operations ..
Three basic parameters:
- One or more targets
- A neighborhood around each target
- A function performed within the neighborhood
Neighborhood geometry
- Square
- Rectangular
- Circular with a size selected by the operation

15. 7. Neighborhood Operations ..
Evaluation functions
- Average, maximum, minimum, diversity, majority, etc.

16. 7. Neighborhood Operations ..
Moving window approach
- A function is executed for successive windows. Result of execution is written to the target cell
Moving windows
Average
Diversity
x x x
x x x

17. Neighborhood Analysis-Density Surface

18. 8. 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 or Terrain trafficability

19. The calculation of distance with barriers

20. Generation of a travel-time data layer
Land use data layer
Friction surface

21. The calculation of distance using a spread function
Diagonal distance
by Pythagorean rule

22. Friction surface data layer Start point data layer
Travel time calculation
Friction surface data layer
Start point data layer
Cumulative travel time data layer

23. Friction surface data layer
Travel-time analysis procedure
- A spread function is used to calculate a travel-time map from the friction surface and the start points
Friction surface data layer
Start points data layer
Travel time map

24. Least-Cost Analysis: Path 2
Distance between stops:
Athens to Lathouriza:
About 25km or 15.5mi
Lathouriza to Thorikos: About 36km or 22mi
Thorikos to Sounion: 13km or 8mi
Total: 74km or 45.5mi
From Erin Warford ..

25. 9. Stream Functions
The stream function (also termed a seek function) performs a directed search outward, step by step, from a starting point based on a set of decision rules. The procedure stops when the rules are violated
The output is a trace of paths

26. 9. Stream Functions ..
Applications – use of a seek function to model flow path

27. 9. Stream Functions ..
Application – find path through a sewer system from point A to point B

28. Stream Functions ..
Application – delineate watershed boundaries

30. 10. Viewshed Analysis
The concept of viewshed: the delineation of areas that are viewable from a point

31. 10. Viewshed Analysis Data sources for viewshed analysis Topography
Surface feature locations & heights of obstructions
Viewer positions
Targets (optional)
Viewshed map showing areas visible from one or more viewing positions. Shaded areas are hidden from view

32. 10. Viewshed Analysis Viewing parameters
- Maximum viewable line-of-sight distance
- Location of viewing point
- Vertical and horizontal angle of view
- Viewing direction

33. Viewing parameters

34. Viewshed
The above maps show the results of analyses around Saddleback (left) and Old Blue (right) mountains. On the maps, green areas are visible from the location cited (shown in yellow), while gray areas are obstructed from view. The Appalachian Trail is shown in red.

35. M. Dolce, Buffalo State College
scenic lookouts
M. Dolce, Buffalo State College

36. From Erin Warford

37. Viewshed
esri

38. Readings
Chapter 5,6,9,10