topic Re: Combining Rasters question in AEC (Architecture, Engineering and Construction) Questions

Combining Rasters question

KatePope — Wed, 09 Oct 2019 23:23:04 GMT

In ArcGIS Pro I have two rasters; one is a single value (0) rectangle, one is line based with 2 values (1 and 2). I need to combine them into one raster with all three values. The rectangle represents off-road values and the line based raster represents two types of roads.

Any pointers would be appreciated.

Re: Combining Rasters question

DanPatterson_Retired — Thu, 10 Oct 2019 02:52:13 GMT

usually

Conditional evaluation with Con—Help | ArcGIS Desktop and perhaps

How to change NoData cells to a value—Help | ArcGIS Desktop

assume you have 'roads' and 'nonroad'. assume that your 'roads' either have a value for the road type surrounded by no data... you could use

Con(IsNull('roads'), 'nonroad', 'road') Do check the exact syntax, but in essence, you want to put/place the nonroad values into the nodata areas of the road raster.

There are other ways, but you should be aware of a few things.

If your rasters both have classes 1, 2, 3... then the above will really foul things up, unless you produce a unique classification scheme...

Perhaps add 10 to the 'road' classes to reclass them to 11, 12 and 13

Con(IsNull('roads'), 'nonroad', 'road' + 10)

You will end up with 1, 2, 3 and 11, 12, 13, representing all the classes in both rasters.

Other approaches are possible, but the above is food for thought.

Re: Combining Rasters question

David — Thu, 10 Oct 2019 14:13:57 GMT

You might be able to combine them together with the Raster Calculator in ArcGIS Pro. [raster1 + raster2 = raster3] It helps that one raster has a value of zero, then it won't change the cells that have a 1 or 2 from the other raster once they are combined. Here is a video that explains it.