[gdal-dev] Retrieving 3DEP data via GDAL's WCS driver...

[Carl Godkin]

Hi Jukka,

That's very interesting.  Thanks a lot.  I wonder if I can figure out how
the X dimension is being changed to (or interpreted as) such a large range.

Certainly something that I can dig into step by step.

I can try sending your findings along to the USGS and hope that someone
there takes an interest.  This is a potentially very useful facility and I
would be surprised if no one else had tried using GDAL tools with it!

Thanks again,

carl


On Sun, Nov 1, 2020 at 11:37 PM jratike80 <
jukka.rahkonen at maanmittauslaitos.fi> wrote:

> Hi,
>
> By adding "-- debug on" into your command it is possible to get details
> about what GDAL is doing. Here are the main parts from the log
>
> gdal_translate
> "WCS:
> https://elevation.nationalmap.gov:443/arcgis/services/3DEPElevation/ImageServer/WCSServer?version=2.0.1&coverage=DEP3Elevation
> "
> test.tif -projwin -107.03 37.28 -107 37.25 -projwin_srs EPSG:4326 -tr 100
> 100 --debug on
>
> GDAL:
> GDALOpen(WCS:
> https://elevation.nationalmap.gov:443/arcgis/services/3DEPElevation/ImageServer/WCSServer?version=2.0.1&coverage=DEP3Elevation
> ,
> this=000002944175BD50) succeeds as WCS.
> GDAL: Using GTiff driver
> Input file size is 40075015, 20498394
> GDAL: Using GTiff driver
> 0GDAL: GDAL_CACHEMAX = 1632 MB
> GDAL: GDALDatasetCopyWholeRaster(): 33*42 swaths, bInterleave=0
> WCS: DirectRasterIO(8122982,14330794,3340,4196) -> (33,42) (1 bands)
>
> WCS: Requesting
>
> https://elevation.nationalmap.gov:443/arcgis/services/3DEPElevation/ImageServer/WCSServer?SERVICE=WCS&REQUEST=GetCoverage&VERSION=2.0.1&COVERAGEID=DEP3Elevation&SUBSET=x%28-20037507.0672000013,-11911185.14836644%29&SUBSET=y%284474012.1150791775,4478208.115037268%29&SCALESIZE=x%2833%29,y%2842%29&Format=image/tiff
> HTTP:
> Fetch(
> https://elevation.nationalmap.gov:443/arcgis/services/3DEPElevation/ImageServer/WCSServer?SERVICE=WCS&REQUEST=GetCoverage&VERSION=2.0.1&COVERAGEID=DEP3Elevation&SUBSET=x%28-20037507.0672000013,-11911185.14836644%29&SUBSET=y%284474012.1150791775,4478208.115037268%29&SCALESIZE=x%2833%29,y%2842%29&Format=image/tiff
> )
> HTTP: libcurl/7.70.0-DEV OpenSSL/1.1.1g zlib/1.2.3
> WCS: GDALOpenResult() on content-type: multipart/related; boundary="wcs";
> start="GML-Part"; type="text/xml"
> GDAL: GDALOpen(/vsimem/wcs/000002944175BD50/wcsresult.dat,
> this=0000029441C0D9A0) succeeds as GTiff.
> GDAL: GDALClose(/vsimem/wcs/000002944175BD50/wcsresult.dat,
> this=0000029441C0D9A0)
> ...10...20...30...40...50...60...70...80...90...100 - done.
> GDAL: Flushing dirty blocks:
> 0...10...20...30...40...50...60...70...80...90...100 - done.
>
> Image test.tif looks somehow corrupted from the right side.
> The only WCS request that GDAL sends can be found from the log. I removed
> url-encoding for clarity
>
>
> https://elevation.nationalmap.gov:443/arcgis/services/3DEPElevation/ImageServer/WCSServer?SERVICE=WCS&REQUEST=GetCoverage&VERSION=2.0.1&COVERAGEID=DEP3Elevation&SUBSET=x(-20037507.0672000013,-11911185.14836644)&SUBSET=y(4474012.1150791775,4478208.115037268)&SCALESIZE=x(33),y(42)&Format=image/tiff
>
> Unfortunately the server returns the GeoTIFF within a multipart content
> with
> some GML. I do not know how to extract the GeoTIFF from the multipart
> package so I could compare the results obtained by using WCS service
> directly with curl or a browser. But because GDAL does not do much for the
> result, just extract the tiff part and write it into separate GeoTIFF, I
> suppose that it is the WCS server that generates the corrupted output.
> However, the request that GDAL sends feels odd to me. Compare the projwin
> in
> gdal_translate command with subsets in the GetCoverage
>
>  -projwin -107.03 37.28 -107 37.25
> SUBSET=x(-20037507.0672000013,-11911185.14836644)
> SUBSET=y(4474012.1150791775,4478208.115037268)
>
> Subract the numbers and notice that subset x is 8126321.919 meters while
> subset y is 4196 meters.
> I can see number 4196 also in this line of the log
> WCS: DirectRasterIO(8122982,14330794,3340,4196) -> (33,42) (1 bands)
>
> Perhaps the meaning is to create SUBSET=x() so that it is 3340 meters wide,
> not 8126322? And maybe the ESRI WCS server creates a corrupted tiff when it
> receives a somewhat lunatic request?
>
> -Jukka Rahkonen-
>
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> --
> Sent from: http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html
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