Perfect. Thanks so much! And thank you for showing the syntax for gdalwarp as well as how to use gdal_edit.py. I would not have figured out these options without you help.
Best regards, Rich On Thu, Mar 29, 2018 at 1:23 PM, Even Rouault <[email protected]> wrote: > On mercredi 28 mars 2018 18:16:45 CEST Richard Greenwood wrote: > > I have a question that is probably more "user" than "developer". Is there > > different place that I should post my question? > > > > I don't think that I understand -srcnodata. I assume that -srcnodata "0 0 > > 0" on a 3 band image means that all 3 bands have to be 0 to be "no data" > > but I think what I'm seeing is that if any to the 3 bands is 0 then that > > pixel is considered to be "no data". Am I mis-understanding -srcnodata? > > Richard, > > That depends on the utility / algorithm. > > For gdalwarp, -srcnodata "0 0 0" will imply by default -wo > UNIFIED_SRC_NODATA=YES > See http://www.gdal.org/structGDALWarpOptions.html# > a0ed77f9917bb96c7a9aabd73d4d06e08 > > For gdalbuilvrt / VRT (and other raster formats in general), nodata is > evaluated on each band independantly. > Unless you specify the NODATA_VALUES metadata item. > > gdalbuildvrt out.vrt in1.tif in2.tif > gdal_edit.py -mo "NODATA_VALUES=0 0 0" > > Then utilities/algorithms that can use mask bands (not all can do however) > will behave as you expect. > > Even > > -- > Spatialys - Geospatial professional services > http://www.spatialys.com > -- Richard W. Greenwood, PLS www.greenwoodmap.com
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