Calculating number of cells/area of one layer in a map (trying to use Tabulate Area)

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02-17-2021 03:07 PM
AndreaGG6
New Contributor II

Hello again! I'm still a newbie in arcgis and I'm having troubles with one of my assignments:

I created a corridor model because I wanted to create the most suitable path where mountain lions can cross. In my screenshots, I'm showing this path created by running the corridor model (purple line between sites) however, I would like to integrate this data with another one of my layers. For instance, I would like to know how much of these paths are protected in the various protection statuses. I have protection statuses ranging from values 1 to 4 (least protected to fully protected) as you can see, so I would like to see how much of these land covers are the corridors involved in?  I tried to do this by using Tabulate Area tool, but when I try to specify my paths as an input raster, the software is detecting them as an invalid extent  Any ideas of how I can do this?

AndreaGG6_0-1613602757586.png

 

AndreaGG6_1-1613602940260.png

 

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DanPatterson
MVP Esteemed Contributor

Something is still bothering me still.

Use Copy Raster and save both files to a new folder (short, no spaces, no fluff, like "C:\work")

Make sure that you specify a *.tif output, not an esri raster or any other format,

Make sure that you specify the cell size, snap raster and extent to be that of you cats layer.

Then do the work.  If all else fails, you can zip and attach that folder with the two tif files. so we can have a look if needed


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DanPatterson
MVP Esteemed Contributor

Are both files in the same coordinate system?  And is that coordinate system a projected one?

What exactly was the extent set to?  (you do that through the Environments tab of the tool)


... sort of retired...
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AndreaGG6
New Contributor II

Both layers are projected in NAD 1983 Zone 11N (meters) and my map coordinate system is WGS 184 (decimal degrees). I set the output coordinate system in Environments as NAD 1983 too. Could the map units be the problem?

AndreaGG6_0-1613610199787.png

AndreaGG6_1-1613610256694.png

 

 

 

 

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DanPatterson
MVP Esteemed Contributor

NAD 1983 is a datum, not a coordinate system.

IF both layers are in your UTM NAD 1983 Zone 11N, then set your map units to it.
This means you must have something in your map that set the units to decimal degrees (with a NAD 83 datum).

Open a new map, move your two layers into it, check to see if the map is set to the appropriate UTM zone.

If your area of interest is limited, I would clip to a smaller extent that to minimize calculations.

Then do your tabulate stuff.

But again, confirm the coordinate system (even checking the raster extent to make sure they are in meters)

Good luck


... sort of retired...
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AndreaGG6
New Contributor II

Okay

-Everything is set in meters

-Map display units are set to meters
-Extent of ALL layers is set to meters
Output coordinate system on environments are set to NAD 1983 UTM Zone 11N just like the layers but still can't run the tool.  **Could I be using the wrong tool for my purpose? 

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DanPatterson
MVP Esteemed Contributor

Still not convinced about your coordinates.

raster_properties.png

This is what coordinates should look like for a mercator style projection (MTM is similar to UTM).

Notice the big numbers,  I am at latitude 45ish N, so I am about 5 million meters from the equator.  If your properties show really small values, then your raster is in decimal degrees and your raster isn't projected.

Do this for both.

Tabulate by area will work IF everything is correct.

You could use other methods, like "Combine"  which would produce a new classification showing where

class A in raster 1 matches with the various classes in raster 2 ... etc for the various combinations in both rasters.  Then you have to figure out how much.

It is the little things,

  • like mismatched extents,
  • wrong projectiong,
  • different cell sizes (haven't gotten around to mentioning that yet)
  • snap raster not specified
  • raster projection method
  • plus more

Now since this is an assignment, and I taught for many years... remember, it isn't the answer but the journey to it, so document everything that you have done and tried... even if it doesn't work out!!!  

Tell your instructor I said so 😉


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JayantaPoddar
MVP Esteemed Contributor

Could you share the screenshots of extent and spatial reference of Mountain_Lion_Corridors layer?



Think Location
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AndreaGG6
New Contributor II

Sharing the map properties, extent and spatial reference of both layers I'm trying to tabulate

map extent.pngmap properties.pngScreenshot_5.pngStatus.png

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JayantaPoddar
MVP Esteemed Contributor

The extents look just fine as per the Spatial Reference. Fill all the required parameters (including output table), and try to run the Tabulate Area tool. Let us know if the issue still persists, or a new error message pops up.



Think Location
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DanPatterson
MVP Esteemed Contributor

also try saving to a new location.  Extents do look fine.  Protected status is bigger (quick mental math),

you may want to set the analysis extent to that of the cats since that is the area you are interested

Now.  If that doesn't work, clip both, save both to a new files (Copy Raster tool)


... sort of retired...
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