[Gdal-dev] vrt & overviews

[Frank Warmerdam]

On 11/10/05, Vincent Schut <schut at sarvision.nl> wrote:
> [Sorry if this message appears twice, I accidentally sent it using my
> other mail account which is not subscribe to the list...]

Vincent,

I rejected the other copy, but did enable that account to post directly
to the list in the future.

> before I start generating overviews for all of my SRTM data, the following
> question: when the sourcebands of a VRT file have overviews, will these
> overviews be used when accessing the VRT file? E.g. I have one VRT file
> which mosaics all my SRTM data tiles and which I use to cut and/or warp
> the pieces of elevation data that I need. Does it make sense to generate
> overviews for each tile, so these will be used when resampling the vrt
> file (like using gdal_translate to cut a piece of srtm at a much lower
> resolution)?

The VRTSourcedRasterBand type of VRT will indeed take advantage of
underlying file overviews if present.

Best regards,
--
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent