Why won't my rasters line up?

08-02-2012 06:30 AM
New Contributor III
I have several rasters that do not seem to line up, despite having been created using the same snap-raster and processing extent. They each cover numerous states at a 30m cell size. One is a polygon-to-raster conversion of town polygons. The others are rasters that were extracted-by-mask using a dissolved form of the town polygon layer. I feel as though I have tried everything to remedy this issue. I've tried re-extracting them all, changing processing extents, changing snap rasters, re-projecting them, and resampling them. Yet, they continue to be misaligned by about a cell, in some areas only. When I am zoomed-out, I can see one showing behind the other at outside edges of the extracted image, on both sides of the image, where a column or row of value-laden pixels changes to NoData. As I zoom in, much of what I see goes away, but not all of it. If I zoom in a lot, there are still some cells that are misaligned, and in using the identify tool, I find that they do actually have values and are not visual artifacts. While I don't think that I need to meet this level of precision with my current work, I would really like to understand what is happening here... Whether it is a product of my order of operations, a program error, issues with the projection, etc. Any thoughts would be most appreciated!
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