nav[aria-label="Primary Navigation"] { padding: 0; & ul { list-style: none; width: 100%; display: flex; flex-direction: row; justify-content: start; align-items: start; gap: 30px; padding: 0; & li { margin: 0; } & ul li { list-style: none; } } }

Suitability Modell - Map in Content Pane

EvaDuerkop

Hello everyone,

I have a question concerning the suitability values that are displayed under my suitability map in the Contents Pane. I am using ArcGIS Pro Vers. 2.9 and have chosen a suitability scale from 1-10 in the model. However, the values of the displayed suitability map randomly change. I have attached a screenshot where the suitability map and the values are displayed and are ranging from 0.41 to 10. From my understanding, this should be from 1-10 due to the scale that I have set beforehand. When I change certain things in the transformation pane this number changes.

Does anyone know what this range actually displays and why it changes?

Thanks,

Eva

Screenshot 2022-01-03 152841.png

Rudolf de Munnik TenneT.JPG

Find more posts tagged with

Accepted answers

KevinMJohnston

I see from the image in the correspondence with Steve you are using the percent weighting method. In the Suitability Modeler, when you specify weights as percents, we multiply the criterion values by the identified percent. That is, if the weight for a criterion is 25%, we multiply each value in the input criterion by .25.

Why does your minimum value not equal 1? Let’s say you have three input criteria. The percent weights you have specified for the 3 criteria are 25%, 25% and 50%. For a particular cell location, the value for each criterion are: criterion 1 = 1, criterion 2 = 1, and criterion 3 = 1. The final suitability value for that cell will be 1 * .25 + 1 * .25 + 1 * .5 = .25 + .25 + .5 = 1.

But then let’s say for another cell, the values for the criteria are (1, 3, 1). The final suitability value for that cell will be 1 * .25 + 3 * .25 + 1 * .5 = .25 + .75 + .5 = 1.5.

In the Suitability Modeler we output the actual weighted sum value from the percent weighting. In your situation, you probably have no location in your study area that has all 1’s for each criterion, therefore the minimum will not be 1. This same logic holds why your maximum value in not 10; you probably have no locations that have all 10’s.

However, if you are familiar with the Spatial Analyst Weighted Overlay tool, the actual weighted sum values are linearly transformed (in this case stretched) to the evaluation scale (the suitability scale). As a result, the range of the output is the same as the suitability scale being used for the transformations.

We suggest using the actual weighted sum values but from this discussion, we may add a check box to the Suitability tab indicating whether you want us to normalize your values to the suitability scale. You will then have a choice to do either.

All comments

SteveLynch

What format is your input criterion, is it a .tiff or a fgdb raster or an Esri grid?

What happens if you create a full resolution Suitability raster (hit run at the bottom of the Suitability pane)

Please post a screen shot of the transformation pane showing the 2 graphs.

EvaDuerkop

I have 13 input criterion and they are all in the fgdb raster format.

When creating a full resolution raster the range has changed to 2.11-9.29. So it doesn't display the full suitability scale.

I have attached a screenshot with the transformation pane of one of my input criterion.

Screenshot 2022-01-04 085841.png

SteveLynch

Eva

Would it be possible for you to zip the fgdb and email it to me together with the weight values?

slynch@esri.com

Thanks

-Steve

KevinMJohnston

But then let’s say for another cell, the values for the criteria are (1, 3, 1). The final suitability value for that cell will be 1 * .25 + 3 * .25 + 1 * .5 = .25 + .75 + .5 = 1.5.

EvaDuerkop

Thanks for your detailed answer Kevin!

This all makes sense and I agree that it would be beneficial to include a check box with the possibility to normalize the values to the suitability scale. I have read a few papers about the evaluation of suitability models and one step of the process was to calibrate the model to the whole range of the suitability scale. This was mentioned as important when comparing the results of different sites or models (e.g. Brooks, Robert (1997): Improving Habitat Suitability Index models. In: Wildlife Society Bulletin 25, S. 163–167 or Theuerkauf, Seth J.; Lipcius, Romuald N. (2016): Quantitative Validation of a Habitat Suitability Index for Oyster Restoration. In: Frontiers in Marine Science 3, S. 64.)

LyssaSalger

Kevin,

Late reply, but the idea of a check box for normalizing values to the intended scale would be very helpful in future versions/updates, especially as a new user to the tool. In that same vein, as a new user, does the multiplication weighting method return the intended suitability scale at the end of adding data and processing the map? I was using that initially but saw that every time I ran the model with new criteria the scale was way out of bounds of the intended scale (1-10) and maybe its my not completely understanding of the relationship between the assignment of values to specific ranges/values in the transformation pane and the suitability scale, but the usage of whole numbers in the transformation pane and on the suitability scale are kind of confusing me. I'm sorry if that didn't wholly make sense but I just want a 1-10 scale and didn't go into this with the intention of using percent weighting, but maybe its better. I am using ArcGIS pro v. 3.6.

Lyssa

Join the Conversation

Signed in members can post, follow updates, and more. New here? Register a free account.

Quick Links

Community Help
Find useful guides, FAQs, and documents to help you navigate and make the most of Esri Community.