[gdal-dev] Reprojecting GeoTIFFs with Overviews?

[Jason Greenlaw - NOAA Affiliate]

My apologies for not being clear about my reasoning. If you're still
curious, I've updated the image to better illustrate what the overviews
should look like and why they shouldn't be recomputed (at small scales,
fewer streaklets are drawn):  http://jgreenlaw.org/gdal/ngofs-wl.png

Thanks for the information, I will reproject the overviews individually.

Jason


On Thu, Jan 10, 2013 at 2:47 PM, Even Rouault
<even.rouault at mines-paris.org>wrote:

> 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.
>
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