ArcGIS .asc file and Geoprocessing Tools - Values are Changing

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01-15-2021 02:49 PM
DebbieH
New Contributor II

I have an .asc grid file that I would like to be able to clip, convert to an ESRI grid, and also use the Set Null tool on. However, when I try to use any of these tools, the Values in the grid file change. I am so confused. For example, in the original .asc grid file, the max value is 1.478. When I run a the Clip too, the max comes out at 5.8928. All the cell values change (and it isn't applying a meters to feet conversion, I checked that out). Has anyone run into something like this?

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DebbieH
New Contributor II

Dan, you hit the nail on the head. The TOC is actually not displaying the max correctly for the .asc grid. Even after I built pyramids, it is still off.  The range that results after I use geoprocessing tools is the correct range. Displaying unique values in the raster layer properties confirms this.

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DanPatterson
MVP Esteemed Contributor

What is the coordinate system? and was it specified?

What was used for specifying the cell size, extent  and whether a snap raster was used?

are you assessing the maximum based on the map legend or have you looked at the before and after historgrams?


... sort of retired...
DebbieH
New Contributor II

Dan, you hit the nail on the head. The TOC is actually not displaying the max correctly for the .asc grid. Even after I built pyramids, it is still off.  The range that results after I use geoprocessing tools is the correct range. Displaying unique values in the raster layer properties confirms this.

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SteveLynch
Esri Regular Contributor
What happens when you use CopyRaster and create for example a fgdb raster from the .asc raster?
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