[gdal-dev] Re: C# bindings - setting up progress delegate for Gdal.Open()

Maksim Sestic max at geoinova.com
Tue Jan 3 08:20:01 EST 2012


Hm, that's strange. I'm using Gdal.Open() to fetch WMS graphics, for example:

Dim ds As Dataset = Gdal.Open("<GDAL_WMS><Service
name="WMS"><Version>1.3.0</Version><ServerUrl>http://wms.agiv.be/inspire/wms/orthobeeldvorming</ServerUrl><CRS>CRS:84</CRS><ImageFormat>image/png</ImageFormat><Transparent>True</Transparent><Layers>RGB</Layers><Styles></Styles></Service><DataWindow><UpperLeftX>3.76302095985856</UpperLeftX><UpperLeftY>50.9987228424621</UpperLeftY><LowerRightX>3.76629196690679</LowerRightX><LowerRightY>50.9968195506639</LowerRightY><SizeX>2439</SizeX><SizeY>2255</SizeY></DataWindow><Projection>EPSG:4326</Projection></GDAL_WMS>",
Access.GA_ReadOnly)

...returns requested dataset, which I further save to disk using appropriate
Driver and CreateCopy() method. It works correctly. I hope that above
example does not perform GetCapabilities() at all?

I was thinking about above case, when Gdal.Open(...) actually reads a raster
dataset from WMS. First it creates "grid" of tiles if pixel size is larger
than BlockSizeX/Y. Then it reads tile by tile from server, merging them all
at the end into the final dataset. Downloading each tile would trigger
progress change. Setting BlockSize to i.e. 256x256 pixels (instead of
default 1024x1024) should make it granular enough for progress bars.

Regards,
Maksim Sestic


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