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Cutting rasters to precise extent and cell size

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12-06-2016 07:27 AM
RobertPace
Deactivated User

I have four raster layers (DEM, Slope, Aspect, Soils) all in the same GCS (WGS_1984) stored in a geodatabase.

I want to clip all four rasters such that the output will have the same # of rows/columns, X&Y cell size, and extent.  I've had great success in clipping DEM, Slope, and Aspect so that everything matches up.  The issue is with the SOILS raster, which regardless of whether I use Extract By Mask, Clip, or Data Extraction the output raster will differ in number of columns/rows, X&Y cell size, or extent.  When Extracting By Mask, I use DEM, Slope, or Aspect as the mask.

It is imperative that all four rasters match precisely in extent, cell size, and columns/rows in order for me to use the data with MaxEnt.

I've attached screencap of an excel showing the rows/columns, cell size (x & y), and extent for the different data layers.

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11 Replies
RobertPace
Deactivated User

I think I finally made some headway in solving this issue.  I am not sure if all these steps are necessary, but this does seem to work in cutting the raster data layers precisely.  I first ensure everything is in the same geographic coordinate system (WGS_1984).  I then cut the source data (which is a larger extent than needed) to a smaller extent that is still larger extent than needed. If needed I resample all these smaller data layers with the appropriate cell size (that of DEM raster).  I next cut the resampled data layers using "extract by mask" using the DEM raster layer as the mask, and under Environment | Processing Extent | Snap to Raster = DEM raster.  This produces raster output that is precisely the same extent and cell size.

RachelBormann
Deactivated User

I've had this same issue when I've used Maxent.  I solved the issue by running the "incorrect" layers through Raster Calculator as follows:

- open the "incorrect" layer in a map document,

- enter the "incorrect" layer in the map algebra expression (double click on the raster name),

- set environment settings:

   - processing extent as the "correct" raster

   - raster mask as the "correct" raster

This has worked for me every time (rasters line up to umpteenth digit).