This tutorial will provide you with a step by step process to utilize this powerful modeling tool.

1. National Aeronautics and Space Administration
Princeton's
Maximum Entropy v3.3.3e
“MaxEnt 101”
Kelsey Herndon (Project Lead)
Sydney Neeley
Dashiell Cruz
Ryan Schick
A Tutorial

2. How can you create an environmental suitability map?
Princeton’s Maximum Entropy (MaxEnt) is used for species distribution
and ecological niche modeling.
Image: www.cs.princeton.edu

3. 1. In Excel, you will first need to add your data into
three columns.
1. This may also be done in Notepad or Wordpad,
but Excel has some operational features that
may prove beneficial when working with large
datasets.
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

4. 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
www.cs.princeton.edu/~schapire/maxent; the
Java runtime environment can be obtained
from java.sun.com/javase/downloads.
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
available here.
Step 2: Downloading
Instructions
Credit: www.cs.princeton.edu
Credit: www.cs.princeton.edu

5. Step 3: Open all environmental layers of interest into ArcMap....i.e. Aspect,
digital elevation, landfire, slope, and soil maps

6. 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

7. 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
“Mask” raster.
Step 5: Set the Environmental
parameters

8. Step 6: Extract each of the environmental layers by the
mask.

9. 1. This can be checked
by
1. “Right clicking” 
Properties  Source
 Raster
Information
2. [Hint:] Copy or
Screenshot this
information for
referencing
purposes.
Step 6.1: All of your Raster’s should now have the same Information

10. Step 7: Convert each masked file from “Raster to ASCII”
*Proper file management will be critical during this entire process!

11. • 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

12. Step 8: Now we are ready to setup a “MaxEnt Run.”
1. Maximize the MaxEnt file you
downloaded.
2. Click the Settings tab
1. Click the “Advance” tab
then load your Bias (.csv)
file you created earlier [If
applicable].
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
“Random Test
Percentage”
4. Next, prepare to set the
“Environmental & Sample
Layers.”

13. 1. The “Sample” layer is the file
we created in slide 3.
1. We named it
(Therealsites.csv)
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:
MaxOutput1 or
MaxOutput_01”
4. You are now ready to “Run”
the Model
Step 9: Setting the
“Environmental” &“Sample”
Layers

14. Step 10: Running the Model
1. This process can take
some time.
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
“slide 13.”

15. Step 11: Obtaining/Interpreting the
Results
1. Open the Internet Explorer
Icon in your Output file.
1. This will display an
interactive html page with all
of your results.

16. • 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.
Results