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Environmental Modeling Environmental Modeling
Basic GIS Functions forBasic GIS Functions forSuitability Index ModelingSuitability Index Modeling
GIS Functions for Suitability IndexGIS Functions for Suitability Index
► Overlay and bufferOverlay and buffer
► The fundamental difference between GIS The fundamental difference between GIS and other computer mappingand other computer mapping
VectorVectorRasterRaster
courtesy: Mary Ruvane, http://ils.unc.edu/courtesy: Mary Ruvane, http://ils.unc.edu/
3. Overlay3. Overlay ► Union, Intersect, and IdentityUnion, Intersect, and Identity
► Clip, Erase, and UpdateClip, Erase, and Update
Logic OverlayLogic Overlay
► Finding areas where certain conditions occurFinding areas where certain conditions occur
► Boolean logicBoolean logic
Mary Ruvane, UNC –Chapel HillMary Ruvane, UNC –Chapel Hill
INPUT Feature UNION
Feature# ATTRIBUTE #
ATTRIBUTE1 0 1 02 A 2 1023 B 3 1034 C5 D
OUT INPUT Feature UNION Feature# # ATTRIBUTE # ATT1 1 0 1 02 1 0 2 1023 2 A 14 2 A 2 1025 3 B 2 1026 3 B 17 2 A 3 1038 3 B 3 1039 4 C 3 10310 5 D 3 10311 4 C 112 4 C 2 10213 5 D 2 10214 5 D 115 1 2 102
UnionUnion
OUT Pop Elev PopRank PopWeight PopW*R EleRank EleWeight EleW*R Sum# # ATT # ATT 1 1 12 2 E 2 1003 3 V 2 1004 2 E 3 1505 3 V 3 1506 4 G 3 1507 5 S 3 1508 4 G 2 1009 5 S 2 100
IntersectIntersect
4. Approximation4. Approximation ► Buffer and Buffer RegionBuffer and Buffer Region► Near and Point DistanceNear and Point Distance
GRID Functions - Spatial GRID Functions - Spatial AnalystAnalyst
Distance, Density, Surface Analysis, Distance, Density, Surface Analysis,
Cell Statistics, Neighborhood Cell Statistics, Neighborhood Statistics, Zonal Statistics Statistics, Zonal Statistics
Cumulative Travel CostCumulative Travel Cost
Friction Surface Data Layer
Start Point Data Layer
Cumulative Travel Time Data Layer
Cost Weighted DistanceCost Weighted Distance
DEMDEM Friction Friction surfacesurface
Cost weighted distanceCost weighted distanceS. Fritz and S. Carver GIS/EM4 2000S. Fritz and S. Carver GIS/EM4 2000
Least-Cost Analysis: Path 1
Path 1 with topography (above) and archaeologically-known sites (left).The background (left) is the cost layer—the darker color = higher costDistance: about 69 km (42 mi)
Shortest PathShortest Path
http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=An_overview_of_Spatial_Analyst
ArcGIS online help
View Shed AnalysisView Shed Analysis
► Highways and Highways and towers clipped to towers clipped to study area.study area.
► DEM converted to DEM converted to grid in ArcToolbox grid in ArcToolbox and a TIN was and a TIN was constructed with constructed with 3D Analyst. 3D Analyst.
► Cell towers and Cell towers and highways overlaid highways overlaid in 3D visualization in 3D visualization in ArcScene.in ArcScene.
► Viewshed Viewshed performed from cell performed from cell tower location and tower location and overlaid on TIN.overlaid on TIN.
Suitability AnalysisSuitability Analysis
► Elevation, Slope, Elevation, Slope, Proximity to Road Proximity to Road were variables were variables chosen.chosen.
► Grids were Grids were created based on created based on these variables these variables and reclassified.and reclassified.
► Combined Combined through raster through raster calculations in calculations in Spatial Analyst to Spatial Analyst to compute a final compute a final suitability suitability analysis.analysis.
Viewshed AnalysisViewshed Analysis
► 3 scenic lookouts3 scenic lookouts► Field verify – may be natural Field verify – may be natural
or man made elements or man made elements obstructing viewobstructing view
3-D Draping3-D Draping
► Superimposed with other thematic layersSuperimposed with other thematic layers
Bowling Green
Z=10
Cell StatisticsCell Statistics
Calculate stats for multiple layers
Majority, Minority, Maximum, Minimum, Mean, Medium, Range, Standard deviation, Sum, Variety
Neighborhood StatisticsNeighborhood Statistics
3 4 5 0 1
6 8 3 1 5
3 4 0 2 1
3 8 0 5 1
6 7 5
5 7 5
8 8 6
8 7 8
Richness Interspersion
Moving windows