[gdal-dev] Reprojecting GeoTIFFs with Overviews?

[Even Rouault]

Le jeudi 10 janvier 2013 19:03:33, Jason Greenlaw - NOAA Affiliate a écrit :
> Norman,
> 
> Unfortunately that's not an option - In this case, my overviews are
> generated separately as individual .ovr files, e.g.:
> 
> NGOFS_WL.tif
> NGOFS_WL.tif.ovr
> NGOFS_WL.tif.ovr.ovr
> NGOFS_WL.tif.ovr.ovr.ovr
> NGOFS_WL.tif.ovr.ovr.ovr.ovr
> 
> I'm then stitching them together into a single image with gdal_translate
> -co COPY_SRC_OVERVIEWS=YES  before attempting to reproject the result.
> 
> Here's an example of what it looks like:
> http://jgreenlaw.org/gdal/ngofs-wl.png
> 
> In each overview, the "streaklet" arrows actually need to be rendered at
> the proper resolution; I can't simply interpolate the original image.
> 
> Perhaps I'm out of luck and need to reproject each of the .ovr files and
> the .tif files separately before combining them?

As indicated in the GeoTIFF driver documentation, COPY_SRC_OVERVIEWS only 
works for CreateCopy() API, i.e. the one used by gdal_translate. gdalwarp used 
the Create() API instead. That was the pedantic part of the answer.

Yes, if you don't want the overviews to be recomputed from the reprojected 
image (the link to the image you provided doesn't really show why computed 
overviews can't be used, anyway...) , the only option is to warp each source 
overview level separately, and then recombine the result.