topic Re: Extract by Mask - Resampling Options? in ArcGIS Spatial Analyst Questions

Extract by Mask - Resampling Options?

SuzanneMonette — Mon, 31 Jan 2011 18:52:18 GMT

Hello Everyone,

I'm using the extract by mask tool to pull out values from a Landsat imagine raster and it works great in terms of where there's no data in my mask file there's no data in the extracted raster and that the mask and extracted rasters cell boundaries line up. However, if my understanding is correct when it does the extraction it resamples using nearest neighbour - my mask raster is 20m and the Landsat is of course 30m.

My question is, can I change that re-sampling method to bi-linear? Nearest neighbour really isn't the best option here.

I have also tried resampling the landsat raster first, however I haven't figured out how to get the cells of the resampled Landsat scene to align with my mask raster. I've tried setting the extent to match that of my clip raster and I've also tried setting a snap raster even though the two are different cell sizes. Nothing so far has worked.

Any ideas would be great!

Thanks!

Sue

Re: Extract by Mask - Resampling Options?

LeoLadefian1 — Fri, 04 Feb 2011 18:22:16 GMT

In the Extract by mask tool click on Environments and then Raster Storage Settings, there you should be able to select Bi-linear.

For the Extent problem, try Environments, General Settings, then under extent browse to the mask file and that should give you the extent for the mask to take place.

Re: Extract by Mask - Resampling Options?

SuzanneMonette — Tue, 08 Feb 2011 15:22:50 GMT

Hi Leo,

I thought that setting the resampling technique under raster storage was only for when it built pyramids for a raster? Seems a bit of an odd place to be setting the resampling technique. I ended up using PCI which always seems to do the trick - it's just a pain to have to go back to PCI anytime I want to do something with a raster. If setting the resampling technique for "pyramids" is actually where you reset the sampling technique for extract by mask then that solves the problem for next time!

I believe I did try setting the extent in the environment settings but it can't hurt to give it another go.

Thanks for the ideas!

Sue

In the Extract by mask tool click on Environments and then Raster Storage Settings, there you should be able to select Bi-linear.

For the Extent problem, try Environments, General Settings, then under extent browse to the mask file and that should give you the extent for the mask to take place.