Ask A Cartographer

Shift in a raster after a process

January 23 2012 | 0 comments
Categories: Map Data

Why does a raster dataset shift after a mosaic. For example Mosaicking DEM's. What happens when this occurs. Also, does this occur with bilinear interpolation of a raster?


Mapping Center Answer:

If you do not use a snap raster, then there is a possibility that the cell locations may shift during raster processing. With Snap Raster, you can select one of your input rasters as the one that the other rasters will "snap" to in terms of the grid array. Here is the online help topic for How Snap Raster works.

Also note that some raster processing tools, like the Mosaic to New Raster tool, include an option to set a new coordinate system for the output raster. This can also cause the location of the cells to change.

In regard to the issue with bilinear interpolation—again, the use of a snap raster may alleviate the shifting that you see.

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