What is Model Builder in ArcGIS Desktop and ArcGIS Pro?
Model Builder in ArcGIS automates your GIS workflows. For example, if you run a report every week that buffers, intersects and generates a pivot table… then you can create a single model and run it every week.
Instead of running each tool one-by-one, you create a model that takes your input, transforms it with a series of tools and then outputs it. In other words, model builder connects your input to geoprocessing tools and transforms it to your desired output.
The best part?
When you create a model in model builder, you can run it as part of your daily workflow. For example, you can reuse models and share them for other users to interact with.
Follow along step-by-step below with your own data and tools. Of course, if you have any questions, don’t be afraid to ask in the comment box below.
Model Builder Example – How To Set Up Your First Model
Let’s start with this simple example for how to create a model in model builder. Pretend you work for a company that plans out where pipelines will be built. In order to comply with environmental regulations, the pipeline can’t be 500 meters away from endangered bird nests.
As engineers modify the design of the pipeline often, they would like a spreadsheet every time they change the alignment of the pipeline. In this report, they want to know if the pipeline is within 500 meters of any bird nests.
A model usually consists of at least three elements:
- Input Data (blue squares)
- Geoprocessing Tools (yellow circles)
- Output Data (green squares)
In our model builder example, here are the two inputs:
Input 1. Pipeline alignment (red and black-dashed line)
Input 2. Endangered bird nests
And here’s how these inputs look like on a map:
Tool 1. Buffer pipeline 500 meters
Tool 2. Intersect bird nests with pipeline buffer
Tool 3. Generate report as spreadsheet
Output 1. Buffer, Bird Nests in Buffer, Report
Let’s start with this simple step-by-step example how to build a model in Model Builder.
Step 1 Open Model Builder
First, click the Model Builder icon to start creating a model. This will open the Model Builder window for you to start adding your geoprocessing tools.
Step 2 Add tools to Model Builder
Drag and drop the buffer, intersect tool and Excel spreadsheet conversion tools from ArcToolbox.
Step 3 Enter tool parameters
Double-click each tool (rectangle) and enter in the following inputs and outputs:
Input Features: Pipeline Realignment
Output Feature Class: C:\Temp\Pipeline_Buffer.shp (Make sure this directory exists or create a new folder if necessary)
Linear Distance: 500 meters
Input Features: Bird Nest and Pipeline_Buffer.shp
Output Feature Class: C:\Temp\BirdNest_Intersect.shp
TABLE TO EXCEL:
Input Table: BirdNest_Intersect.shp
Output Excel File: C:\Temp\Report.xls
After entering the inputs and outputs for each tool, the Model Builder window will look like the screenshot below. However, it looks disorganized and the auto-layout tool can help clean everything up.
Step 4 Auto layout
After you click the auto-layout button, the geoprocessing tools, inputs and outputs will rearrange themselves neatly in the model builder window.
Model Builder Example: Running the Model
Of course, we have only built the model up to this point. In order to create the report, we still have to run the model. You can run the model by clicking the ‘Play’ button.
After you run your model, you can add your output feature classes to ArcMap to verify it is correct. By double-clicking the report.xls, it lists all bird nests within 500-meters of the pipeline. In this case, it’s only the California Condor.
Another thing to note is that after you run your model, circles and squares in the model will have shadows. Check (C:\Temp\) to see each product it creates (buffer, intersect and report).
But really, the only output you need is just the report. The buffer and intersect are just temporary (intermediate) data sets. After running a model from the ModelBuilder window, it doesn’t delete all the intermediate outputs (buffer and intersect) that it creates.
So if you want to re-run the model, you can manually go into this folder (“C:\Temp\”) and delete these feature classes. Also, you may have to click the “checkmark” icon next to the “auto-layout” icon to validate the model.
Model Builder Toolbox: Setting up Parameters/Variables
Let’s say another group in your company wants to use this model for the same purpose. But their input data and output data have completely different names.
Instead of static input and output, you need them to be dynamic as parameters. When you set the input data or output data as parameters, users can enter their own data and set their own output paths.
How do you set up model builder parameters?
Step 1 Set model parameters for inputs
Right-click your two input data sets (bird nests and pipeline) and click ‘Model Parameter’
Step 2 Set model parameter for output
Right-click your output data set (report) and click ‘Model Parameter’
But there’s one more thing that we’ll have to change – how it handles intermediate data. ArcGIS Model Builder has a handy command called ‘in_memory’ to handle it.
For each temporary output (buffer and intersect), we can turn these into temporary datasets with ‘in_memory’. For example, double-click the green box (pipeline_buffer) and change it as follows:
After this step, your model should have “P” next to each model parameter. Also, your temporary buffer and intersect output should have ‘in_memory’ for the output.
Delete all the files in (C:\Temp\). Now, when you click ‘Run Model’, it will only create the XLS report. And this is because you set the buffer and intersect as temporary data (in_memory).
How to Create a Toolbox in ArcGIS
Now that we’ve set the input and output as parameters, wouldn’t it be nice if this could be a toolbox on its own? Toolboxes are convenient to share. They look professional. And they are easy to create.
First, let’s empty the parameters so that when we share it, there isn’t a default path. Double-click each model parameter in model builder and empty it.
Once you’ve emptied each parameter, the model should look white like in the screenshot below:
Now, you’ll want to save your model. But you’re going to need a toolbox to do so. After clicking “Save”, click the new toolbox icon in the top-right of the dialog box.
You can name the new toolbox “Pipeline.tbx”. Now, double-click this new toolbox and save the model within the toolbox.
In ArcCatalog, locate where you just saved this toolbox. Expand the toolbox so you can see your new toolset.
Double-click the new toolset that you have created. Now, that we have created parameters and emptied them, you can now dynamically enter in your inputs and outputs.
How To Export a Model as a Python Script
Since ArcGIS 9.0, it has completely overhauled its programming interface from VBA to Python. By using Python libraries, you can extend ArcGIS. But now that Python has been proven to be a great tool, where do you begin? Sure, you can start with python.org but this is a lot of information for you to start with.
Another way to save you time is to use ModelBuilder and create a model for your workflow. Once you get the model working, then export the model as a script (Model > Export > To Python Script). The output of this export provides a great starting point where you can alter the Python code and even include other Python packages.
This is probably one of the best ways for you to begin learning Python scripting in ArcGIS. You can see how ModelBuilder breaks up the code with arcpy modules, script arguments, local variables and the geoprocessing tools.
These are the same code samples you see at the bottom of the ArcGIS Help Library. Each geoprocessing tool has a code sample to use in the Python Window or as a stand-alone script for that particular tool.
Model Builder Iterators
Iterators help repeat a process for a set of inputs in model builder. ArcGIS Model Builder has different types of iterators to repeat processes.
For example, if you want to set multiple distances for buffers at different increments, you can use the ‘FOR’ iterator. Using the buffer tool from our existing model, you can set ‘FROM’ and ‘TO’ variables at different increments.
In the Model Builder window above, we added an iterator to the model. This will dynamically set the buffer distance as described in the ‘FOR’ iterator.
Other iterators available are: ‘while’, ‘row selection’, ‘feature selection’, ‘multivalue’ and more.
Model Builder in ArcGIS Desktop
Because at your job, time is of the essence. You need to provide answers to real-life GIS problems at break-neck speeds.
Model Builder in ArcGIS automates your GIS workflows. When you create a model, it can repeatedly perform your analysis.
Instead of manually running each tool one at a time, try putting them in a model next time.
Model Builder is a robust way to analyze your GIS data and is a huge time saver.