Calculation of area of predicted habitat suitability in km sq in QGIS

[Apoorva Sodhi]

How does one calculate the area of predicted habitat suitability in km sq from a binary map created in QGIS after MaxEnt modelling?

[Food Tributes]

Sorry for the late reply.

Apoorva, I guess you should once read this thread: https://www.researchgate.net/post/Can_anyone_suggest_how_to_calculate_the_area_of_the_suitable_and_not_suitable_habitat_from_the_output_of_MaxEnt_model

Maybe it can be useful to you.

Snehangshu Das

On Thu, 25 Jun, 2020, 12:44 PM Apoorva Sodhi, <apoorv...@gmail.com> wrote:

How does one calculate the area of predicted habitat suitability in km sq from a binary map created in QGIS after MaxEnt modelling?

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[Amir Sohail Choudhury]

Hello

For binary modeling, you need to set a threshold as above this value will be considered as suitable and below it as unsuitable. 

So, this threshold value is generated from the Maxent model itself like Clog log/logistic minimum training presence or 10 percentile training presence or Equal training sensitivity and specificity. You can choose any of it, however, there is no clear criteria for choosing. Many literatures suggested to use all these. 

For calculation purposes in QGIS, you can take the help of manual or  youtube.

Regards

Amir

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Amir Sohail Choudhury

Research Scholar

Wildlife Conservation Laboratory

Department of Ecology and Environmental Science

Assam University, Silchar 788011

B.Sc. (Botany); M.Sc. (Ecology and Environmental Science)
Specialization: Wildlife Ecology and Conservation
Site-Coordinator of two Important Bird Area, Assam (IBCN)

[Michael Bungard]

Is your binary map a reclassed raster? I’m not sure of the precise process in qgis but the principals will be the same as other GIS applications. Convert your binary raster (just the ‘1’s and label the ‘0’s as nodata) to a polygon and from there, calculate area.

[wyclife oluoch]

Dear Apoorva,

Install Semi-Automatic Classification Plugin. Within the SCP, go for Post-Processing then Classification Report. Use your binary raster as the input data. This will provide you with summaries you need plus proportions as percentages. It would be easier if your raster is already projected in metric crs so that you can easily get the values in sq. km. Otherwise you may get values in decimal degrees or other systems in use. I hope this helps. Probably there are many other ways to solve the problem. A simple thing to remember, other than 'predicted suitability in km sq. ... MaxEnt', is that you have a raster file with all pixels having values either 0 or 1. So the program counts 0's and 1's and multiplies by the resolution of each cell, assuming the cells are square in shape as demonstrated in the attached Excel sheet. This should work even when the cell values are more than two, as may be the case of change detection where some cells show an increase, other a decrease, and the rest no change, so you end up with three classes. 

[sa laar]

The link of the video please? 

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