Extract by Mask Rasters don't line up with originals

[KarlZimmer]

Hello all,

I am working with some Landsat imagery that I need to extract certain areas of the raster. I've tried extracting by a polygon mask. The extraction works fine but for some reason the output raster pixels no longer line up directly with the pixels from the original raster. Similary, if I use reclassify to export specific pixel values, these output rasters don't line up either. The shift is quite small, about half a pixel, but I can't figure out why it is doing this. Any ideas? Both the polygon mask and Landsat raster have the same projection so I don't see it being a projection issue.

Any help would be greatly appreciated!

Cheers,
Karl

[RobertBerger]

Hi Karl,

There is an environment setting called snap raster which should also help. The tool help says that it takes the parameter.

Robert

[ThuPhan]

Hi all,

I am also experiencing this problem, though I've check in the environment setting for raster analysis and trying a couple of combination and it still shows the same result. Could anyone in the forum help me to explain why it can happen? I am currently running ArcGIS 9.2 and 9.3.1. Thank you very much for your help.

[SimonLee]

Hi guys. I know this is a very old thread but I met the very same problem when extracting some grid cells using a mask. I found a workaround solution somehow. Try "Extract by polygon" instead of a mask, which works great for me. I'm using arcgis v10. Hope it helps. Thanks

[SimonLee]

Hi guys. I know this is a very old thread but I met the very same problem when extracting some grid cells using a mask. I found a workaround solution somehow. Try "Extract by polygon" instead of a mask, which works great for me. I'm using arcgis v10. Hope it helps. Thanks

Well yes, "Snap Raster" works great. 🙂