Hi All, My apologies if this has been asked previously. I’m relatively new to GDAL and recently was able to get it building with PDFium support using GDAL 3.11 for iOS. I’m the developer of a mapping application which allows users to import GeoPDFs and GeoTIFFs (among many other things). I was able to back port the GetExtent code that is going in to 3.12 and extract the extent from a GeoPDF, which was very exciting!
However, what I’m ultimately trying to do is take a GeoPDF/GeoTIFF and place it
on the map. I do this now with KMZ GroundOverlays by bringing in the four
corner points and transforming the image to fit those points. I’m guessing the
flow I’ll use is something like (and assuming WGS84 just to make things easier):
- Call GDALGetExtentWGS84LongLat to get the envelope
- Call GDALGetGeoTransform to get the geotransfmrm
- Calculate the four corners to get the bounding box:
- LL: (env.MinX, env.MinY)
- UL: (env.MaxX, env.MinY)
- LR: (env.MinX, env.MaxY)
- UR: (env.MaxX, env.MaxY)
- Apply the transformation matrix from the GeoTransform
Does this seem roughly correct? I know there’s GDALWarp but I don’t know enough
about it to know if it would help handle this situation.
Thanks so much!
Cory
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