Overlay analysis roadmap

Summary
This topic provides a brief introduction to overlay analysis and looks at how it should be performed by ArcObjects developers.

About overlay analysis
One of the most basic questions asked of a geographic information system (GIS) is "What's on top of what?" The following are examples of this question:
  • What land use is on top of what soil type?
  • What parcels are within the 100-year floodplain? ("Within" is another way of saying "on top of".)
  • What roads are within what counties?
  • What wells are within abandoned military bases?
  • What is the daily rainfall total for each watershed?
  • Where is the best location to build a new shopping center?
In ArcGIS, these types of questions are answered with the use of overlay geoprocessing tools.

Overlay analysis using geoprocessing

The functionality for performing overlay analysis is available through geoprocessing tools.
The Overlay toolset in the Analysis toolbox contains tools to overlay multiple feature classes to combine, erase, modify, or update spatial features, resulting in a new feature class. New information is created when overlaying one set of features with another. There are six types of overlay operations, all involving the joining of two or more existing sets of feature classes into a single feature class to identify spatial relationships between the input features.
It is common practice to overlay raster data. Tools for raster overlay are located in the Spatial Analyst toolbox in the following toolsets:
  • Local toolset—Local tools operate on a cell-by-cell basis, overlaying individual cells and calculating new output values.
  • Zonal toolset—Zonal tools allow zones defined as polygons or cells of the same value to be overlayed with a raster dataset of continuous values to calculate an output statistic for each zone.
  • Overlay toolset—Overlay tools are used in site selection and suitability modeling, often using weighted combinations or fuzzy logic.
For more information on how to use these tools in a developer scenario, see How to run a geoprocessing tool.

Overlay analysis using ArcObjects

There are no ArcObjects to assist you in this analysis. You need to use geoprocessing tools, as discussed in the previous section, to perform these tasks.


See Also:

Using geoprocessing
Using geoprocessing to develop applications
Executing tools