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Raster bilinear resampling problem

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02-10-2011 05:28 PM
CraigMason
Emerging Contributor
Hi everyone,
I have an forest fire intensity asci file with 200m resolution which i need to be smoother and at 30m resolution. i convert the asci to raster then resample to 30m using a bilinear interpolation, but the resulting raster doesn't make any sense. what am i doing wrong?
here is the original asci file if anyone wants to try for themselves...

http://www.2shared.com/file/Rr619-lV/305_1_Intensity.html

i am using arcgis 9.3, please help!!

thanks,
craig :cool:
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3 Replies
PatrickTaurman
Deactivated User
What do you mean by this?


the resulting raster doesn't make any sense.


How does the output not make sense?  Any details you can provide would be useful.
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CraigMason
Emerging Contributor
What I mean by not making sense is:
Here is the raster intensity before interpolation (cell size 200m)

http://i83.photobucket.com/albums/j316/craigusmcvegas/rasterbeforeinterpolation.jpg

And here is the raster after resampling at 30m using bilinear interpolation

http://i83.photobucket.com/albums/j316/craigusmcvegas/rasterafterinterpolation.jpg

As you can see, it has not smoothed the raster at all but made a funky pattern...

Still havent solved this problem...
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RobertBerger
Occasional Contributor
Hi Craig,

Bilinear resampling usually works well when you are creating a more coarse resolution from a higher resolution. You are doing the opposite at a quite large difference (200m vs. 30m). Please try using the cubic convolution resampling method which might help.
Note here that you might be merging two concepts: one is a resampling used to create the new pixels, the other is a display resampling mechanism. The geoprocessing tool you run will still create square pixels and when you zoom in you will see square pixels if your display resampling is nearest neighbor. So, in addition you can change the display resampling to bilinear which might give you a display that you are looking for.
I hope this helps.

Robert
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