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Saving temp file result from Elevation Void Fill in image analysis window changes raster values-adds artifact

Question asked by JCHarvey on Mar 4, 2020

Saving an ARCMAP temp file (the result of a raster function) produces raster values different from the values in the temp file.   In this image, I originally set the values of the DEM inside the polygons to NoValue, then used the Elevation Void Fill raster function to populate the NoValue pixels to produce a 'synthetic DEM' with new values within those zones. The image analysis window raster function dialog creates a temporary file output that has realistic smooth gradients- (good job for the algorithm). If I then save the temporary interpolated file, either through the analysis window, or by exporting from the table of contents, the interpolated values change between the original temporary file, and the save or exported file, including introducing the step function artifact seen in the image below.  Interpolated values change by several 10s of meters, the step function is about an 80 meter step. Both the temp file and the saved files are 16 bit signed integers. I use the original raster dataset extent, so no resampling (and all values outside the interpolated region stay identical). Projection doesn't change. Saving to Tiff, Grid, or ESRI BIL, etc, doesn't matter. I'm running out of ideas to troubleshoot. 


My questions:  Why does the saved file have different value and artifacts not in the temp file, and how do I save the temp file as it is without the artifacts?


Top image is the temp file from the raster analysis function, bottom image is the saved/exported TIFF.