ArcGIS Role in Maxent Modeling

62 Pages·2014·1.68 MB·English

ArcGIS Role in Maxent Modeling
Christopher Woods
Christopher.R.Woods @leidos.com

Carpinteria, CA
Modeling
(cid:132) Remember that all models are wrong; the practical
question is how wrong do they have to be to not be
useful

− Statistician, George E. P. Box

− Empirical Model-Building and Response Surfaces
(1987)

©2014 LEIDOS. ALL RIGHTS RESERVED.
What is Maxent
(cid:132) Maxent stands for ‘Maximum Entropy’

− Type of inductive modeling that uses presence only
occurrence data along with environmental variables to
derive a probability of occurrence or potential suitable
habitat.

(cid:132) Software can be downloaded from
• http://www.cs.princeton.edu/~schapire/maxent/

©2014 LEIDOS. ALL RIGHTS RESERVED.
About Maxent
(cid:132) Runs in a separate application
(cid:132) Inputs:
− CSV file of occurrences
− ASCII Grid of Environmental Layers
(cid:132) Outputs:
− ASCII Grid of Potential Suitable Habitat
©2014 LEIDOS. ALL RIGHTS RESERVED.
Why use Maxent?
(cid:132) Limited Range or Habitat data exists for species of
interest
(cid:132) Occurrence records available
(cid:132) Locates ‘Potential’ Suitable Habitat
(cid:132) Subject Matter Experts needed to ground truth results to
highlight areas needed for more focused study to
determine presence or absence

©2014 LEIDOS. ALL RIGHTS RESERVED.
Environmental Layers Used in Maxent

PRISM Precipitation
• Example of
environmental
PRISM Temperature
raster layers
used in Maxent Ruggedness
• Layers are
stacked upon Aspect
each other within
the model
Vegetation

Distance to Water

Soils
©2014 LEIDOS. ALL RIGHTS RESERVED.
Occurrence Data Used in Maxent
(cid:132) Occurrence data (point locations) are added to the model
(cid:132) Stored in a CSV file containing X,Y positions in the same
coordinate system as environmental layers

Species Observation
©2014 LEIDOS. ALL RIGHTS RESERVED.
Occurrence Data Used in Maxent
(cid:132) Occurrence data (point locations) are added to the model
(cid:132) Stored in a CSV file containing X,Y positions in same
coordinate system as environmental layers
(cid:132) Maxent uses the point occurrence data to look for
relationships within the stack of environmental layers

Aspect
Ruggedness
Species Observation
Prism Temperature
Prism Precipitation
©2014 LEIDOS. ALL RIGHTS RESERVED.
ArcGIS Role in Maxent
Modeling
ArcGIS Role
(cid:132) Creating Snap Grid for Study Area
(cid:132) Create Environmental Layers
(cid:132) Align Layers to snap grid using the same projection,
pixel size and grid extent
(cid:132) Create CSV of Occurrence Data
(cid:132) Populate Samples with Data (optional)
(cid:132) Convert Environmental Data to ASCII
(cid:132) Convert Results from ASCII to Imagine/Tiff/Grid
(cid:132) Symbolize Results on Map
©2014 LEIDOS. ALL RIGHTS RESERVED.