Extract by Mask not including full extent of the mask

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10-08-2013 02:33 PM
KarlZimmer
New Contributor II
Hello,

I have numerous raster .img files that I'm trying to clip to a feature class containing several irregular shaped polygons. It seems to work correctly for the most part, but it seems pixels around the polygon edges are not always including. It appears there may be a threshold where if >50 % of the pixel isn't covered by the mask it is excluded. However, I would like it so that any pixel intersected by the polygon mask is included.   I have set the cell size and snap to raster environment, but was wondering if there are additional environments I need to set. I have attached a screen shot to show the issue. I have tried both clip and extract by mask and get the same result.

Any advice would be greatly appreciated.

Thanks in advance.

Karl
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3 Replies
TimWitt
Frequent Contributor
Karl,

Maybe this thread can help you?

Tim
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JimCousins
MVP Regular Contributor
The criteria is based on the cell center. If the cell center falls within the polygon mask, the cell is included. If you want to include any cell that is touched, apply a buffer to your mask polygon that is equal to 1/2 your raster cellsize. That should grab the cells currently touched, and not extend the polygon mask far enough to include additional raster cells.
Best Regards,
Jim
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JamesTaysom
New Contributor
Buffering helps some but if the polygon cross a corner instead of a side the buffer doesn't get it quite to the center of the cell.
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