topic Re: How to cookie-cut an raster file with an polygon? in 3D Questions

How to cookie-cut an raster file with an polygon?

NicolinaLindblad — Fri, 30 Oct 2015 17:48:35 GMT

I need to cut out the shapes of some lakes in my raster layer, I have the lakes both as polygons and raster. This would really help! Thank you! Using ArcMap 10.3

Re: How to cookie-cut an raster file with an polygon?

DarrenWiens2 — Fri, 30 Oct 2015 17:52:03 GMT

There are many ways to do this:

1.) Extract by Mask using either raster or polygon

2.) Clip via Image Analysis Window using polygon

3.) Con using raster

Re: How to cookie-cut an raster file with an polygon?

NicolinaLindblad — Fri, 30 Oct 2015 17:54:10 GMT

Sorry, I might have been unclear, I would like to remove the areas of the lakes from my rater layer! So the opposite result from "extract mask". You don't happen to know?

Re: How to cookie-cut an raster file with an polygon?

DarrenWiens2 — Fri, 30 Oct 2015 17:57:11 GMT

Use Con.

Con(IsNull("LakesRaster"),"YourOtherRaster")

edit: ...or SetNull

edit: ...or this extremely convoluted method

Re: How to cookie-cut an raster file with an polygon?

DanPatterson_Retired — Fri, 30 Oct 2015 18:00:15 GMT

Are you having issues with things that you would normally use because of nodata values or something? There seems to be more to this question. As Darren mentions, there are many obvious solutions but often considerations of nodata values, raster extents and/or snap rasters are forgotten or omitted.

Re: How to cookie-cut an raster file with an polygon?

DanPatterson_Retired — Fri, 30 Oct 2015 18:03:26 GMT

Setting values to NoData with Set Null—Help | ArcGIS for Desktop

ahhh

Re: How to cookie-cut an raster file with an polygon?

NicolinaLindblad — Fri, 30 Oct 2015 18:25:24 GMT

Thank you! So if my raster with the lakes that i want to remove are called "Lakes" and my other raster layer is called "Uganda". How would the "Set Null" function be written then, I am very new to GIS, so appreciate all the help!

Re: How to cookie-cut an raster file with an polygon?

DanPatterson_Retired — Fri, 30 Oct 2015 18:35:00 GMT

read the link carefully, this is the simplest because you have your lakes layer so you lakes have some value, hopefully other than 0, so wherever the lake is "true" (ie it has a value) then it assign a value of no data to the output layer, hence moving your unganda data into the output and leaving no data cells where the lakes once were.

Should this not be to your liking, then I can give examples involving the Con for conditional operations, or Plus with conditions etc. The trick is to make it simple...you need nodata (i assume otherwise you would have specified) where the lakes once were.. good luck

Without an expression

The image below uses an input raster (InRas1) as the condition. When the value for a cell on InRas1 is true (not 0 or NoData), NoData is assigned to that cell location; otherwise, the value in InRas2 is written as the output value.

Re: How to cookie-cut an raster file with an polygon?

DarrenWiens2 — Fri, 30 Oct 2015 18:38:28 GMT

I think it is like:

SetNull(if this condition is false, use these cell values)

...so:

SetNull("Lakes","YourOtherRaster")

Re: How to cookie-cut an raster file with an polygon?

DanPatterson_Retired — Fri, 30 Oct 2015 19:16:52 GMT

just like in the help files, no helping too much

Re: How to cookie-cut an raster file with an polygon?

NicolinaLindblad — Sat, 31 Oct 2015 08:24:28 GMT

Thank you, but function didn't work unfortunantely. It could not run.

Re: How to cookie-cut an raster file with an polygon?

NicolinaLindblad — Sat, 31 Oct 2015 08:31:57 GMT

Thank you, I have read through it three times but I still didn't get it to work...

Re: How to cookie-cut an raster file with an polygon?

DanPatterson_Retired — Sat, 31 Oct 2015 09:07:04 GMT

provide the raster names then and the specific error message
also, we have been assuming that you have actually check that everything is in the same coordinate system, by examining each layers extent and coordinate system in properties (right-click on the layer, select properties and examine the tabs)
you are working in a path with no spaces
the type of rasters you are using

"not working" is like saying "it won't start" no context, not enough information to be of help

Re: How to cookie-cut an raster file with an polygon?

BenLeslie1 — Fri, 06 Nov 2015 08:52:36 GMT

This "extremely convoluted method" is not a bad way to try if you're new to Arc.

Basically you need to create a layer that is the inverse of your lakes polygons.

You can do this by drawing a polygon layer that covers entirely your raster - then use the Union tool to union this polygon with your lakes polygon - then delete the lakes from the resulting layer.

Next use the tool search and search for "clip raster" and choose Clip (Data Management). Use the result of the Union tool as the Output Extent and ensure the Maintain Clipping Extent option is ticked.