topic Re: Raster Intersect/Union in ArcGIS Pro Questions

Raster Intersect/Union

GraceManks — Sun, 17 Oct 2021 20:51:47 GMT

Hello!

I am working with raster for the first time. For an assignment, we need to create two raster layers and find the areas that do not overlap.

When we used vector data, we could union and intersect the areas in order to find this out. I was wondering if there are equivalent tools for raster that I could use to achieve the same outcome?

Thank you!

Re: Raster Intersect/Union

DanPatterson — Sun, 17 Oct 2021 21:57:55 GMT

Con (Spatial Analyst)—ArcGIS Pro | Documentation

Conditional evaluation with Con—ArcGIS Pro | Documentation

The key is to set the analysis extent through the Environments tab to the combined extent (union) of both rasters. If both rasters overlap assign them a value of 1 otherwise 0

Re: Raster Intersect/Union

GraceManks — Sun, 17 Oct 2021 22:21:42 GMT

@DanPatterson

I have now set the extent to union of inputs! Thank you!

If I had a layer called "total_land", and the overlapping areas I want to remove from it are called "town_distance" and "lake_distance", would I use do outras="total_land"-("town_distance"+"lake_distance") or is there a conditional equation I should be using instead?

I've never used conditional before so am finding it quite confusing!

Thank you!

Re: Raster Intersect/Union

DanPatterson — Sun, 17 Oct 2021 22:32:11 GMT

You said you had two raster layers, Is one total_land ? and is town_distance and lake_distance two other rasters or just one?

Conditional statements are just logic. If town_distance or lake_distance (TD_LD) has a value ( eg. > 0, assuming 0 is the smallest value) and total_land has a value (eg > 0, again assuming 0 is the smallest value), then

if .... (total_land > 0) and (TD_LD > 0), do this if True, do this if False)

ergo

Con((total_land > 0) and (TD_LD > 0), 1, 0)

0 is the areas that don't overlap. This is why it is important to set the analysis extent to the union of both rasters. Another snag, is nodata values in either raster... I would reclass nodata to some value prior to applying Con ... longish story, but think on it)

Re: Raster Intersect/Union

GraceManks — Sun, 17 Oct 2021 22:40:01 GMT

Thank you I will try that now! And I said two layers for simplicities sake... There are actually quite a few layers going on unfortunately!

Re: Raster Intersect/Union

JayantaPoddar — Mon, 18 Oct 2021 01:04:06 GMT

Also check this out in Raster Calculator

Con((IsNull( "image1.tif") & IsNull("image2.tif")),0,(Con((IsNull ( "image1.tif") | IsNull("image2.tif")),1,2)))

Replace image1.tif and image2.tif with your raster file names.

In the resulting raster, ignore the cells with value 0.

Cells with Value 1 are the ones where overlapping cells of any one of the two layers is Null.

Value 2 indicates both the overlapping cells are not Null.

You could open the attribute table to see the count of cells in each value.

Re: Raster Intersect/Union

SafaÜzümcü — Wed, 10 Nov 2021 11:15:47 GMT

Kırmızı kare test alanlarının altında bir raster dosyası var. Raster dosyasında siyah mı yoksa yeşil mi olduğunu daha fazla bilmek istiyorum. insect komutunu çalıştıramıyorum. Nasıl yapabilirim?

Re: Raster Intersect/Union

SafaÜzümcü — Wed, 10 Nov 2021 11:20:58 GMT

There is a raster file under the red square test areas. I would like to know more if it is black or green in the raster file. I can't run the insersect command. How can I do it?