Thanks! it works a follow up "bonus" question I get the same problem when trying to create a mosaic by warping to images to a new dataset.
my code is basically copied from the "GDAL Warp API Tutorial" page http://www.gdal.org/warptut.html and adding: psWarpOptions->padfSrcNoDataReal = new double(0); On Feb 29, 2012 11:03 AM, "Even Rouault" <[email protected]> wrote: > Selon Ophir Yoktan <[email protected]>: > > Several errors : > 1) The NoDataValue and HideNoDataValue elements are only valid under the > VRTRasterBand element, not SimpleSource > 2) You want to change SimpleSource to ComplexSource, and add a > <NODATA>0</NODATA> element in it. (well basically rename your current > NoDataValue to NODATA. > > > > I'm trying to build a mosaic, and I rely on the NoDataValue feature to > > treat some parts of the image as transparent. > > However, it appears that GDAL doesn't work as expected. > > > > I also created a very simple test case using a vrt dataset and > > gdal_translate - and I get the same results (that is - the 2nd image > draws > > over the 1st image, ignoring "transparent areas") > > > > I have to 100X100 image files with a white marking (different in each > file) > > over black background (black being exactly equal to 0) > > I built a simple vrt file: > > > > <VRTDataset rasterXSize="100" rasterYSize="100"> > > <VRTRasterBand dataType="Byte" band="1"> > > <ColorInterp>Gray</ColorInterp> > > <SimpleSource> > > <SourceFilename relativeToVRT="1">a1.tif</SourceFilename> > > <SourceBand>1</SourceBand> > > <SrcRect xOff="0" yOff="0" xSize="100" ySize="100"/> > > <DstRect xOff="0" yOff="0" xSize="100" ySize="100"/> > > <HideNoDataValue>1</HideNoDataValue> > > <NoDataValue>0</NoDataValue> > > </SimpleSource> > > <SimpleSource> > > <SourceFilename relativeToVRT="1">a2.tif</SourceFilename> > > <SourceBand>1</SourceBand> > > <SrcRect xOff="0" yOff="0" xSize="100" ySize="100"/> > > <DstRect xOff="0" yOff="0" xSize="100" ySize="100"/> > > <HideNoDataValue>1</HideNoDataValue> > > <NoDataValue>0</NoDataValue> > > </SimpleSource> > > </VRTRasterBand> > > </VRTDataset> > > and I run the command: > > > > gdal_translate mosaic.vrt mosaic.tif > > > > The result is identical to image `a2.tif`, instead of being a combination > > of `a1.tif` and `a2.tif` > > > > I got the error using gdal 1.8 and 1.9 > > > > any ideas? > > > > >
_______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
