GeoprocessingGeoprocessing is a fancy name for Spatial Operations
So what is Geoprocessing?Processing or manipulating of geographic/spatial data to create a new dataset.
Example of a simple process
Water
Sugar
Flour
MIXED DOUGH
A typical GeoprocessingInput
DatasetOutputDataset
Geoprocessing
UnprojectedData Project
ProjectedData
• A process contains tool• And a tool has parameters
Input Data Output DataTool
Geoprocessing/Model building
ProcessProcess
Process
Tools in ArcToolbox• There are literally hundreds of Geoprocessing tools available in ArcGIS!
• Most of the time you will use only a few of them
Geoprocessing MenuCommonly used tools are available from Geoprocessing menu!
Environment Settings
Application level settings affect all tools and menus Tool settings affect one execution
of one tool
Workspace settings
• Current and scratch workspace
• Output coordinate systems
ArcToolbox has many tools
Map Overlay• Map overlay brings data from multiple
layers into one• There are two basic categories of map
overlay functions1. Functions that combine attribute data
&2. Functions that do not
Overlay operations in ArcGIS
1. Erase2. Clip3. Union4. Intersect
Overlay operations combine more than one layers into one.Some of the extraction function can also be considered as overlay function
Extraction only & does not combine attribute from layers
Combine attributes from layers
Select by locationCan’t truncate the roads at the boundary!
Clip is the rescue!Clip is used to cookie cut the original ROAD layer into a smaller layer
What is Clip?Clip is used to cookie cut the desired areas
EraseOnly the features outside the Erase feature are kept, everything else are erased
DissolveDissolve is used to aggregate features based on specified attributes
If you don’t choose an attribute, it will dissolve all into one!
How to simplify the landuse data
DISSOLVE
Dissolve wizard
What is Union?Union combines two polygon layers together
What is Intersect?Computes geometric intersection of two layers
Example of intersectAreas common between the two layers.
INTERSECT
3500’ buffer 2000’ road buffer
Buffering Lines
250’Buffer
Using attribute table in buffering
Variable buffering using attribute
Multiple Ring Buffer
Multiple Ring Buffer
Buffer around Toxic Sites & water well location