topic Re: clip hole in raster in ArcGIS Mapping and Charting Questions

clip hole in raster

RickCheney — Mon, 08 Feb 2016 15:00:21 GMT

For example, if I have a raster layer of Digital Elevation which represents the United States and I want to keep everything except the state of Texas. I have a vector layer polygon of the state of Texas which I hope can be used to clip or mask or intersect the raster data.

How do I get the raster DEM layer with an area cutout or missing where Texas was?

Re: clip hole in raster

WesMiller — Mon, 08 Feb 2016 15:21:44 GMT

I've never clipped a raster with a donut hole but you can clip a raster based on geometry with Clip—Help | ArcGIS for Desktop

Re: clip hole in raster

RickCheney — Mon, 08 Feb 2016 15:30:13 GMT

I can clip the raster data to get the state of Texas but not the United States without Texas.

Re: clip hole in raster

DanPatterson_Retired — Mon, 08 Feb 2016 16:38:28 GMT

keep outside Extract by Polygon—Help | ArcGIS for Desktop

Re: clip hole in raster

RickCheney — Mon, 08 Feb 2016 16:52:43 GMT

It looks like the Extract by Polygon only accepts X Y coordinates for the Polygon that represents Texas, if I was extracting or masking a rectangle the X Y coordinates would be easy but I'm not sure how to specify a shape as complex and the state of Texas with X Y coordinates.

Re: clip hole in raster

RebeccaStrauch__GISP — Mon, 08 Feb 2016 16:58:49 GMT

you may want to see if this works for you Erase but for raster

Re: clip hole in raster

WesMiller — Mon, 08 Feb 2016 16:58:51 GMT

Have you thought about Clip—Help | ArcGIS for Desktop each state then Make Mosaic Layer—Help | ArcGIS for Desktop them back together minus Texas?

Re: clip hole in raster

RickCheney — Mon, 08 Feb 2016 17:18:48 GMT

The solution in the Erase but for raster thread is to use Raster Calculator but as far as I can see the Raster Calculator uses only Raster data and I don't have raster data for the shape that I what to cut out. Maybe I can convert my vector area into raster and then use the Raster Calculator.

Re: clip hole in raster

RickCheney — Mon, 08 Feb 2016 17:23:20 GMT

I was only using the US map and the state of Texas as an example, but I will look into Making a Mosaic Layer

Re: clip hole in raster

DanPatterson_Retired — Mon, 08 Feb 2016 17:24:27 GMT

Well you could cheat... convert texas to a raster giving it a constant value of zero and setting the extent to be the size of the dem. Convert the nodata area of texas the raster to 1, so you end up with an indicator grid... not-texas = 1, texas = 0 then multiply (Times) the dem by the indicator grid... sounds complicated but is really fast to do

Re: clip hole in raster

RickCheney — Mon, 08 Feb 2016 17:33:47 GMT

You are right, it sounds very complicated but I'll give it a try.

Re: clip hole in raster

XanderBakker — Sat, 11 Dec 2021 20:43:45 GMT

I find it strange that the user needs to specify the coordinates as a list of arcpy.Points() in the Extract by Polygon—Help | ArcGIS for Desktop tool. Not very user friendly I would say.

Attached a sample toolbox that you can extract to a folder on you disk and test.

The result will be something like this:

It will use the (first) selected polygon for the erase.

The code used is:

def main():
    import arcpy

    # parameters
    ras = arcpy.GetParameter(0)
    fc = arcpy.GetParameter(1)
    method = "OUTSIDE"
    ras_out = arcpy.GetParameterAsText(2)

    # get first polygon of fc
    polygon = arcpy.da.SearchCursor(fc, ('SHAPE@')).next()[0]

    # create list of points
    points = [pnt for pnt in polygon.getPart(0)]

    # Check out the ArcGIS Spatial Analyst extension license
    arcpy.CheckOutExtension("Spatial")

    # Execute ExtractByPolygon and save result
    result = arcpy.sa.ExtractByPolygon(ras, points, method)
    result.save(ras_out)

if __name__ == '__main__':
    main()

Note; it has't been tested thoroughly, and may crash when using a complex geometry.

Re: clip hole in raster

RickCheney — Mon, 08 Feb 2016 19:33:13 GMT

Thanks, it looks like this tool is going to work. I got the tool setup and I tried using it. I got an error the first time but I will continue testing and maybe tweaking and see if I can get it to work. Thanks again.

Re: clip hole in raster

XanderBakker — Mon, 08 Feb 2016 20:32:29 GMT

Can you share the error you obtained?

Re: clip hole in raster

DanPatterson_Retired — Mon, 08 Feb 2016 20:48:17 GMT

and I was done hours ago

Re: clip hole in raster

RickCheney — Tue, 09 Feb 2016 15:18:11 GMT

Sorry about the delay in responding. The error information is below.

Traceback (most recent call last):

File "E:\holeInRaster\EraseRaster.py", line 24, in <module>

main()

File "E:\holeInRaster\EraseRaster.py", line 20, in main

result = arcpy.sa.ExtractByPolygon(ras, points, method)

File "c:\program files (x86)\arcgis\desktop10.3\arcpy\arcpy\sa\Functions.py", line 1300, in ExtractByPolygon

extraction_area)

File "c:\program files (x86)\arcgis\desktop10.3\arcpy\arcpy\sa\Utils.py", line 53, in swapper

result = wrapper(*args, **kwargs)

File "c:\program files (x86)\arcgis\desktop10.3\arcpy\arcpy\sa\Functions.py", line 1295, in Wrapper

extraction_area)

File "c:\program files (x86)\arcgis\desktop10.3\arcpy\arcpy\geoprocessing\_base.py", line 504, in <lambda>

return lambda *args: val(*gp_fixargs(args, True))

RuntimeError: Object: Error in executing tool

Failed to execute (EraseRaster).

Re: clip hole in raster

XanderBakker — Tue, 09 Feb 2016 17:24:18 GMT

Hi Rick Cheney , looking at the error, I can see that your paths do not have special characters, so that is not causing the problem. The script fail at the line where the actual work takes place. There are many factors that influence that line. There are environment settings that might impact correct functionality of that line of the tool, coordinate systems of the inputs, and other aspects.

Most likely it has to do with the variable "points" which holds the list vertices that form the polygon. As you must have noticed from the image I posted I used a very simple polygon (nowhere near the complexity of Texas). Maybe the number of vertices or perhaps an invalid geometry can crash the ExtractByPolygon tool.

Could you post the featureclass of polygon of Texas that you are using? I can mimic some data around Texas and see if I can reproduce the error.

Also can you specify the coordinate system of you data frame, both the inputs and the geoprocessing environment?

Or can you test with a simple polygon (few number of vertices) to see if the tool works? If so it is most likely the geometry that causes the problem.

Re: clip hole in raster

RickCheney — Tue, 09 Feb 2016 22:20:30 GMT

I'm going to test with a simple polygon and report back with how that works.

Re: clip hole in raster

DarrenWiens2 — Tue, 09 Feb 2016 22:48:30 GMT

I don't see any mention of Extract by Mask, which seems to me the tool to use, to create an output that you can feed into Set Null (or Con) to remove the unwanted parts of the original raster.

Re: clip hole in raster

XanderBakker — Tue, 09 Feb 2016 23:25:02 GMT

The advantage of ExtractByMask is that it allows a featurelayer as input and doesn't require a list of points that forms a polygon. However, in combination with Set Null or Con I would rather rasterize the polygons and use the Con statement to obtain the desired result.

Thinking again... what if you do use the ExtractByMask tool and use you states, but you select Texas and invert the selection (everything selected exact Texas). Wouldn't that generate the yield the desired output?

I'm gonna give it a try and will report back later...