6. 6
Raster VectorRaster Vector
•• CellsCells
•• ContinuousContinuous
•• CellCell--basedbased
•• Points, lines, polygonsPoints, lines, polygons
•• DiscreteDiscrete
•• ShapeShape--basedbased
Feature and Grid LayersFeature and Grid Layers
••Feature layers use vectorsFeature layers use vectors
••Grid layers use rastersGrid layers use rasters
ArcGIS represents elements of the realArcGIS represents elements of the real
world for analysis:world for analysis:
7. 7
OperationsOperations
Has its own environment
(not part of geoprocessing)
The ArcGIS Spatial Analyst Toolbar
Can compose
Map Algebra
expressions
Has dialogs for the most
commonly-used tools
8. 8
ArcGIS Spatial Analyst and the
ArcToolbox Window
Opens ArcToolbox
Provides dialog interface for tools
Hints and
link to
help
Uses geoprocessing environments
(right-click to set)
Has Map Algebra tools
Raster CalculatorRaster Calculator
•• Works on ArcMap raster layers and gridWorks on ArcMap raster layers and grid
data setsdata sets
–– Uses environment settings for layer inputUses environment settings for layer input
•• Type in GRID Map AlgebraType in GRID Map Algebra
•• Perform mathematical functionsPerform mathematical functions
•• Combine multiple rastersCombine multiple rasters
9. 9
Raster CalculatorRaster Calculator
Con([slope] > 15, 1, 0)
Condition (If Slope is greater than 15 , Output = 1 if
less than 15, Output raster = 0)
Where is the ground suitable to build a house?
Modeling spatial problemsModeling spatial problems
•• Models help us understand and solveModels help us understand and solve
complex problemscomplex problems
––Simplify realitySimplify reality
––Combine geographic layers to answerCombine geographic layers to answer
questionsquestions
•• Example: “What type of forest does the pineExample: “What type of forest does the pine
marten prefer?”marten prefer?”
Reality GIS layers Habitat suitability
Mixed forest
40-90 year old forest
High density forest
Forest height > 20m
Mixed forest
40-90 year old forest
High density forest
Forest height > 20m
10. 10
The analysis environmentThe analysis environment
•• Control how an output raster is createdControl how an output raster is created
–– Settings for geoprocessing and Spatial AnalystSettings for geoprocessing and Spatial Analyst
are independentare independent
The output rasterThe input raster
ProjectionMask
Cell Size Extent
Output Workspace
Types of AnalysisTypes of Analysis
11. 11
ReclassificationReclassification
•• Everything within a range becomes theEverything within a range becomes the
same valuesame value
–– E.g.: temperature:E.g.: temperature: --1010 –– 0 = 1 (cold)0 = 1 (cold)
00 –– 10 = 2 (cool)10 = 2 (cool)
1010 –– 20 = 3 (warm)20 = 3 (warm)
3030 –– 40 = 4 (hot)40 = 4 (hot)
Converting Vector Layers toConverting Vector Layers to
RasterRaster
•• Useful for making raster calculationsUseful for making raster calculations
with vector datawith vector data
14. 14
Fire AnalysisFire Analysis
• Locate areas of high risk
• Analyze ‘what if’ scenarios
•Analyze the
•spread potential
•Preplan fires
Analyze Transportation CorridorsAnalyze Transportation Corridors
• Foresee
problems with
new corridors
• Assess and propose new transport
routes
