Introduction of Geoprocessing

Lecture 9

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.

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.

Geoprocessing with ArcGIS The most important thing to understand about geoprocessing

in ArcGIS Desktop is that all geoprocessing operations

involve the use of tools.

This seems not in ArcGIS10

Geoprocessing

GIS project steps

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

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.

Explore system toolboxes

Search any tool you need

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.

Step1: Select your geodatabase as a Default Geodatabase to make sure all outputs will be stored there

Step2: Create a new toolbox

Step4: you can build your model now

Step3: Create a new model

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

DEMOs from the Building Models for GIS Analysis using ArcGIS10

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

Details in next two lectures