Geoprocessing - ArcGIS

(copied from Learning ArcGIS9 Virtual Campus course)

 

Geoprocessing is an integral part of GIS analysis that creates new data from existing GIS data, from which information can be derived to solve problems. When you need to perform many geoprocessing operations or want to be able to easily repeat an analysis, you can create a model to automate and keep track of your workflow. Listed below are key points you should remember about geoprocessing and models.

 

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Geoprocessing tools used for analysis typically fall into three categories: data extraction, overlay, and proximity.

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Geoprocessing tools are accessible from ArcToolbox and ArcCatalog and are stored in toolsets, which are stored in toolboxes.

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Help for geoprocessing tools can be accessed from within the tool dialog boxes.

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The basic building block of a model is a process; a process consists of a geoprocessing tool.

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In a model, processes are connected to represent and execute a geoprocessing workflow.

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Models can be saved, easily modified, and run as many times as needed to perform different analyses and test "what if" scenarios.

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Like all GIS data, models should be documented so they can be shared with others.

 

 

Review questions

  1. What are some of the steps in a geoprocessing workflow?

  2. What do the element symbols in a model indicate?

  3. What is one way a model can help you manage data?

 

Answers

  1. In a typical geoprocessing workflow, you need to determine which tools to use and in what order; find and open the first tool, enter its parameters, and run it; then repeat for each tool in the sequence. After all the tools have run, you examine the final output and make adjustments if necessary.

  2. Element symbols indicate the state of a process—whether a process is ready to run or has already run.

  3. When you add processes to a model, you can flag their output data as intermediate data, then delete it after the model runs.

 

Key terms

 

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buffer

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clip

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element

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geoprocessing

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intermediate data

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intersect

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model

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overlay

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process

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union