3

App

I'm using Openlayers3 and GeoServer 2.9.1 to create an application allowing users to draw an aoi then download it as raw data subsets (geotiff) of a Canada wide data set (also geotiff). I'm using a WCS 1.0.0 GetCoverage request where bbox and Grid Dimensions are dynamically entered.

Issue

When validating the subsets, a simple subtraction of the downloaded data from the original dataset reveals pixel value changes (see image). How can I retrieve raw data subsets without re-sampling errors? It is critical that the pixel values be identical to the original.

Making a GetCoverage request from GeoServer's Demo Request Builder using the same bbox coords as my script gives me the same errors.

Pixel value difference from rasterCalc Pixel value difference

Thoughts?

1

Making a WCS 1.0 request that is not subsampling is pretty hard, it has to match precisely the data set. Better make a WCS 2.0 request, that should give you a much better chance of just performing a pixel by pixel extraction.

  • Thanks! I'll update this post when I get to the bottom of it, but that's a good suggestion to explore. – EdwinA Mar 9 '17 at 17:40

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