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

Intersect and IdentityIntersect and Identity ► Intersect       Intersect      

► IdentityIdentity

ClipClip

EraseErase

UpdateUpdate

               

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

Cell StatisticsCell Statistics

4. Approximation4. Approximation                ► Buffer and Buffer RegionBuffer and Buffer Region► Near and Point DistanceNear and Point Distance

Buffer and Buffer RegionBuffer and Buffer Region

NearNear

Point DistancePoint Distance

NodepointNodepoint

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

AllocationAllocation

Straight Line DistanceStraight Line Distance

Cost Weighted DistanceCost Weighted Distance

Friction SurfaceFriction Surface

Cumulative Travel CostCumulative Travel Cost

Friction Surface Data Layer

Start Point Data Layer

Cumulative Travel Time Data Layer

Cumulative Travel Cost ContoursCumulative Travel Cost Contours

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

Athens

Sounion

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)

Viewshed analysisViewshed analysis

Shortest PathShortest Path

http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=An_overview_of_Spatial_Analyst

ArcGIS online help

Point Point DensityDensity

Contour Contour

Slope and AspectSlope and Aspect

Hillshade and ViewshedHillshade and Viewshed

ViewshedViewshed

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

ViewshedViewshed

A. Toy, SUNY BUffalo

3-D Draping3-D Draping

► Superimposed with other thematic layersSuperimposed with other thematic layers

Bowling Green

Z=10

Crime MappingCrime Mapping

Cut/FillCut/Fill

Cave modelingCave modeling

Cell StatisticsCell Statistics

Calculate stats for multiple layers

Majority, Minority, Maximum, Minimum, Mean, Medium, Range, Standard deviation, Sum, Variety

Majority

Minimum

Mean

Median

Sum

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

Neighborhood StatisticsNeighborhood Statistics

Zonal StatisticsZonal Statistics

Zonal StatisticsZonal Statistics

Cell StatisticsCell Statistics

Markus Erhard et al. GIS/EM4 2000Markus Erhard et al. GIS/EM4 2000