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VeraMaria
(Stranger )
08/15/14 03:12 AM
Nearest Neighbor new Report this article as Inappropriate to us !!!Login to Reply

Hello, I'm Vera from Germany and pretty much unacquainted to the details of ArcGis and Landsat Imagery. Now my question is if the Landsat Imagery is already processed via cubic convolution resampling (as I've read on the USGS homepage), is it then wise to additionally use the nearest neighbor method for geometric correction (for I'm working on a Landsat time-series)? I'm thankful for an answer. Regards, Vera

Edited by VeraMaria on 08/15/14 03:13 AM.



sperryville
(Stranger )
08/22/14 06:53 AM
Re: Nearest Neighbor new [re: VeraMaria]Report this article as Inappropriate to us !!!Login to Reply

Hello Vera,


You may have already figured this out but your assumption is right - Nearest Neighbor would be the best resampling method for geometric correction. This way, you would not be affecting the original values, which have already been affected by the original resampling performed USGS. On a similar note, Nearest Neighbors would be the only approach you would want to use for any classifications or similar discrete value rasters for the same reason as above. Otherwise, your neat, integer class numbers (0, 1, 2, 3, 4) would be lost through interpolation.


If your time series is derived entirely from USGS and they have all undergone geometric corrections, there may be no need to perform additional co-registration - most users have found that USGS georeferencing is quite robust.


 


 


 





VeraMaria
(Stranger )
08/23/14 10:40 AM
Re: Nearest Neighbor [re: sperryville]Report this article as Inappropriate to us !!!Login to Reply

Hello Sperryville!
Thank you for your answer. I hav another question. Since the images are all processed via Cubic Convolution resampling, does that mean, a time-series would not be applicable on the images? Are there any unprocessed Landsat Images available?

Regards, Vera 





sperryville
(Stranger )
08/25/14 09:03 AM
Re: Nearest Neighbor new [re: VeraMaria]Report this article as Inappropriate to us !!!Login to Reply

Hello Vera,


 


Although some remote sensing scientists were not too happy when the USGS adopted cubic convolution, the differences between those derived products and a nearest-neighbors product would be rather minor, particularly now that the radiometric resolution has been increased from 8-bit to 12-bit. I would not suggest seeking out unprocessed Landsat images, even if you could find them. The way that Landsat imagery are being produced today is a tremendous improvement over older systems, even from 10 years ago (notably, of course, that they're free). Only in very particularly circumstances would this be a problem, and for a time series classification, you should have no worries.





VeraMaria
(Stranger )
08/27/14 09:28 AM
Re: Nearest Neighbor new [re: sperryville]Report this article as Inappropriate to us !!!Login to Reply

Thanks again, Sperryville! I've now also contacted the usgs, and they told me, that unprocessed images aren't available! Regards 






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