National Aeronautics and Space Administration
Maximum Entropy v3.3.3e
Kelsey Herndon (Project Lead)
How can you create an environmental suitability map?
Princeton’s Maximum Entropy (MaxEnt) is used for species distribution
and ecological niche modeling.
1. In Excel, you will first need to add your data into
1. This may also be done in Notepad or Wordpad,
but Excel has some operational features that
may prove beneficial when working with large
2. The first row of your datasheet is a header line,
and should have three column headings titled:
Species, Longitude, and Latitude.
1. Longitude and latitude can be substituted with
Easting/Northing, X/Y, etc.
3. Under these headings, your data should be
entered or copied.
1. If your data is in a shapefile format, Excel is
able to open .dbf formatted data.
4. Convert the Excel (.xls) file to a (.csv) file by:
1. Save as save as type CSV
5. We named our file “Therealsites”.csv
1. This will serve as your “sample file” for later
Step 1: Producing a Comma-
Separated Value (.csv) File from
Species, Occurrence, & Coordinates
in an Excel Spreadsheet
1. The software consists of a jar file, maxent.jar,
which can be used on any computer running
Java version 1.4 or later.
2. MaxEnt can be downloaded, along with
associated literature, from
Java runtime environment can be obtained
3. If you are using Microsoft Windows (as we
assume here), you should also download the
file maxent.bat, and save it in the same
directory as maxent.jar.
1. You can check the file path by: “clicking” the
maxent.jar icon Show Folder Path.
4. The website has a file called “readme.txt”,
which contains instructions for installing the
program on your computer.
A Spanish translation of a slightly older version of the tutorial,
provided by Paolo Ramoni-Perazzi, is available here.
A modified version of this same translation, provided by Jose
Marrero, is available here.
A Russian translation of the tutorial, provided by Maxim Dubinin, is
Step 2: Downloading
Step 3: Open all environmental layers of interest into ArcMap....i.e. Aspect,
digital elevation, landfire, slope, and soil maps
Step 4: The data were then reformatted to the same datum and projection.
*This data can be checked by:
“right-clicking” each Raster Properties Source Expand Extent
1. A layer was then chosen to serve
as the “Mask” for the rest of the
data to convert each of the layers
into the exact same extent, cell
size, and projection.
2. Follow these steps in ArcMap.
1. Geoprocessing Environments
Change the Output Coordinates &
Processing Extent to match the
Step 5: Set the Environmental
Step 6: Extract each of the environmental layers by the
1. This can be checked
1. “Right clicking”
2. [Hint:] Copy or
Step 6.1: All of your Raster’s should now have the same Information
Step 7: Convert each masked file from “Raster to ASCII”
*Proper file management will be critical during this entire process!
• A bias file may be necessary for your MaxEnt model. It is used to
limit the background points to only surveyed areas.
• Colorado State University has written a tutorial on creating a bias
file that can be found here: CSU MaxEnt Tutorial
[FYI:] Creating a “Bias Sample”
Credit: Colorado State University
Step 8: Now we are ready to setup a “MaxEnt Run.”
1. Maximize the MaxEnt file you
2. Click the Settings tab
1. Click the “Advance” tab
then load your Bias (.csv)
file you created earlier [If
3. Set the Random test
percentage to an amount that
fits with your desired output.
1. We chose 20% of our
total sites as our
4. Next, prepare to set the
“Environmental & Sample
1. The “Sample” layer is the file
we created in slide 3.
1. We named it
2. The “Environmental” layer
are the files that we saved in
our “ASCII Folder”.
1. This is why file management
is critical during this process
3. Set your “Output Directory”
1. Tip: Give each run a
numerical value. [Example:
4. You are now ready to “Run”
Step 9: Setting the
Step 10: Running the Model
1. This process can take
1. Feel free to start another
task during this time.
2. When the Model is finished
running, the “Pop-up”
window will disappear.
1. Your “Results” will be in
the Output Directory folder
you chose in
Step 11: Obtaining/Interpreting the
1. Open the Internet Explorer
Icon in your Output file.
1. This will display an
interactive html page with all
of your results.
• In this example, a map of the San Juan Basin is predicting where
Ancient Chacoan heritage ruins are more than likely to exist.
• Areas that are red are areas in the Basin that MaxEnt has determined to
be more suitable for sites; areas in blue have little to no suitability value.
• This model used aspect, digital elevation models, landfire, slope, and
soil data as environmental inputs.