What is geoprocessing?

Geoprocessing is any GIS operation used to manipulate data. A typical geoprocessing operation takes an input dataset, performs an operation on that dataset, and returns the result of the operation as an output dataset, also referred to as derived data. Common geoprocessing operations are geographic feature overlay, feature selection and analysis, topology processing, and data conversion. Geoprocessing allows you to define, manage, and analyze geographic information used to make decisions.

In other words, any alteration or information extraction you want to perform on your data involves geoprocessing.

In this topic, you'll discover where geoprocessing fits into your GIS project workflow. You'll also take a first look at geoprocessing tools in ArcGIS.

For almost any GIS project, there are certain tasks that must be performed regardless of the type of project. These tasks are typically grouped into four major steps.

Steps and tasks of a GIS project
1	Determine the objectives of the project Identify the problem to solve Break down the problem into measurable criteria Determine data requirements
2	Build the database and prepare the data for analysis Identify and obtain relevant data Design and implement the database Add spatial and attribute data to the database Manage and modify the data
3	Perform the analysis Determine methodology and sequence of operations Process the data Evaluate and interpret the results Refine the analysis as needed and generate alternatives
4	Present the results Create final products for intended audience

As you progress through the four major steps of a GIS project, it's important to document your work. Careful documentation serves as a record of your methodology, so that you can easily duplicate your workflow and share your work with others.

So, where does geoprocessing fit into the steps of a GIS project?

Where geoprocessing fits in

Preparing data and performing analysis are the core of any GIS project, and that is where most geoprocessing operations come into play.

Documentation is an equally important part of a GIS project, and because ArcGIS now includes functionality for documentation, it too can be incorporated into your standard geoprocessing workflow.

The tasks highlighted in yellow represent the stages of your geoprocessing workflow. Depending on what form your presentation takes, you might also use some geoprocessing tools in the last step of your project (specifically, cartography tools), but for the most part, the geoprocessing framework provides functionality for data preparation, analysis, and documentation.

In the data preparation stage, you'll need to create the physical structure of the database and populate it with data. If the data comes from different sources (as it usually does), it will probably require conversion into a common format and coordinate system. You might also need to combine or extract data, create new attributes, check for data errors, or perform other data creation and management tasks to prepare for the analysis.

In the analysis stage, you'll combine operations such as feature selection and overlay in meaningful sequences to reveal geographic relationships among the data. The initial analysis may lead to the need for further analysis requiring additional data, and therefore additional data preparation. Consequently, you may move back and forth between the two phases.

Documentation is perhaps the most overlooked part of a GIS project, but it can play a critical role in a project's outcome. Documentation includes recording information about your data and your methodology.