Introduction of Geoprocessing

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Introduction of Geoprocessing

• Topic 7a
• 4/10/2007

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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 or derived
  data. Common geoprocessing operations, like
• geographic feature overlay
• feature selection and analysis
• topology processing
• 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.

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Geoprocessing

• Geoprocessing is one of the most powerful
  components of a GIS. In ArcGIS Desktop, you are
  provided with a framework for addressing
  geoprocessing tasks, which includes an extensive
  list of geoprocessing tools organized within a
  set of toolboxes.
• You can employ the tools directly or chain them
  together to model a particular workflow. You can
  put geoprocessing tools to work in custom scripts
  and you can create your own tools and toolboxes.
• The geoprocessing framework also provides
  functionality for organizing and managing your
  work environment, performing simple and complex
  analyses, and making your custom tools usable by
  others.

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Geoprocessing with ArcGIS

• The most important thing to understand about
  geoprocessing in ArcGIS Desktop is that all
  geoprocessing operations involve the use of
  tools.

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Geoprocessing
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GIS project steps
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GIS project steps

• 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

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GIS project steps

• 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
• 5. Document your work
• As you progress through the four major steps of a
  GIS project, careful documentation serves as a
  record of your methodology, so that you can
  easily duplicate your workflow and share your
  work with others.

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Find the right tool for the job

• Familiar with the toolbox
• Favorite tab
• Index tab
• Search tab
• Using the index tab to find a tool works well
  when you have a pretty good idea about what the
  tool's name is. Otherwise, you will want to use
  the Search tab.
• If you need more detailed information about the
  tool, you could click the Help button at the top
  of the help panel to open a more comprehensive
  help document for the tool. You can also access
  this information by right-clicking a tool in
  ArcToolbox and choosing Help.

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Explore system toolboxes in the Catalog Tree
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Create your own tool

• In addition to the system tools, toolsets, and
  toolboxes that come with the software, you can
  create your own. For example, you might create a
  new toolbox to store custom script tools for a
  particular project.
• Both system tools and custom tools can be managed
  using ArcToolbox

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Create your own tool

• Within an ArcGIS Desktop session, any changes you
  make to ArcToolbox in ArcCatalog will not
  automatically display in ArcMap.
• To match the ArcToolbox settings in ArcMap or
  other ArcGIS Desktop applications with those in
  ArcCatalog, you have three choices
• Close ArcCatalog before opening another ArcGIS
  Desktop application.
• Save the ArcToolbox settings as the default in
  any ArcGIS Desktop application, then open another
  ArcGIS Desktop application.
• Save the ArcToolbox settings to a file in any
  ArcGIS application. In the ArcGIS Desktop
  application, load the ArcToolbox settings from
  the file.

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Run a tool from the command line

• The command line gives you an alternative to
  using a dialog box to run a tool. You type the
  name of the tool and its parameter values as text
  in the command line, and press Enter to run the
  tool.
• Click the Show/Hide Command Line Window button
  to display the Command Line window

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Create run your own Model

• A model can link tools together to execute
  multiple processes as one operation.
• Models contain geoprocessing tools, but they are
  also considered tools themselves.
• Models allow you to document your methodology and
  share your work with others because they provide
  a record of your workflow

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Create and run your own scripts

• Scripts
• Script is a text file that contains instructions
  for geoprocessing written as lines of code.
• Any processing that you can do with a model can
  also be done using a script. However, scripts
  offer additional functionality that is not
  available using a model.
• To run a geoprocessing script using ArcMap or
  ArcCatalog, you must first attach the script to a
  tool.
• Scripts and models contain geoprocessing tools,
  but they are also considered tools themselves.
• Scripts allow you to document your methodology
  and share your work with others, because they
  provide a record of your workflow

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Script