Environmental GIS Nicholas A. Procopio, Ph.D, GISP nick@drexel.edu Some slides from Lyna Wiggins (Rutgers University)

ArcToolbox

Geoprocessing Tools There are five ways of using geoprocessing tools in ArcGIS: Run (some of) them in ArcMap Run them from ArcToolbox Type them at the command line (Workstation) Use them in a script environment (like Python) Use them in ModelBuilder

What do we want to do? We might want to use a series of geoprocessing tools in an exploratory analysis. As we explore, we want to visualize our results as we work. We might like to change parameter values and see their impact. ModelBuilder is helpful in this exploratory process. Run processes as you go – you may not even want to save the model.

ModelBuilder A model in this context is a sequence of processes made up of data and tools. The model flow chart gives us a visual representation of our geoprocessing work flow.

What do we want to do? If you have a complex sequence of processes that you have to do frequently – or with a number of different datasets – you will want to create and save a model. You may want to: run multiple scenarios – for example, for a build-out analysis, create custom tools and use them inside your model or by themselves, share your model with others.

ModelBuilder ModelBuilder is integrated throughout the ArcGIS product lines – any tool in Toolbox can be used to define a process. These include tools from the Extensions. ModelBuilder helps us create, edit, document and distribute models. After you create a model it can be exported as a script to Python

Create New Toolbox and New Model In ArcCatalog, right-click and create a new Toolbox in a folder that you want to use Then right-click and create and name a new Model

Integrated Model Window ModelBuilder Graphic interface Elements Inputs (blue ellipses) Outputs (green ellipses) Processes (gold rectangles) Drag and drop tools (processes) from ArcToolbox Fill in parameter values in dialog boxes

Model Builder Window

Input Input data can be any of the ArcGIS data types: Coverages Shapefiles Geodatabase feature classes Grids Other ESRI formats

Input Data Not ready to run

ModelBuilder Window Ready to run Model has run Notice shading

Tools in Graphics Interface Some of the tools on the ModelBuilder toolbar are there to help you zoom, pan, and organize your model flow chart Two tools are used frequently: Arrow tool to select Linkage tool to connect inputs, processes, outputs

Example: ModelBuilder

Running a Model We can choose to: Processes turn red as model executes Run a single process Run all ready-to-run processes Run the entire model Processes turn red as model executes We receive status messages with each run.

Editing a Model Right-click on a Model in ArcCatalog and go to Edit. The ModelBuilder window opens and we can begin editing. If you change the model you should save before closing. Prompt reminds you to do this. Note there is no “save as” – only save to model that you opened to edit.

What is a Parameter? In Model Builder, our tools often need required or optional values in order to run. These are parameters. For example, the Buffer tool needs a buffer distance in order to run. We can “expose a parameter” to allow user input. Then we call it a model parameter. To do this we will create a parameter as a variable.

Creating a Parameter Variable The first step is to right-click on a tool in your diagram and select “Make Variable,” then “From Parameter.”

Creating a Model Parameter We now see a new model element, named appropriately.

Creating a Model Parameter The second step is to right-click on this new model element and select “Model Parameter.” Now we see a P label in our model diagram.

Derived Data Data that is output from a process is called “derived data.” If output data from a process is not a final result, it is “intermediate data.” When you right-click on an intermediate output, you will see if it has “Intermediate” checked. Intermediate data is temporary.

Intermediate Data Models run from a dialog box or the command line delete intermediate data automatically. Models run from within ModelBuilder write intermediate data to disk. Your end results will also be flagged as Intermediate by default – you may need to change this setting.

Model Validation In the Model drop down menu in the ModelBuilder window, you have the option to “Validate the Entire Model.” This checks that all of your model parameters are correct and that your input data can be found. Models that need repair (for example, if an input data set was moved from its initial location) will show up in the toolbox with a red X through them.

Export Your Model You can export your model as a graphic – .bmp, .jpg, .emf, .gif, .pdf, .png You can export your model to a Python script. Both are from the Model dropdown menu in the Model Builder window.