[Gdal-dev] questions to overviews and tiles

[Frank Warmerdam]

Christian.Strobl at dlr.de wrote:
> hi list,
> 
> i have only a few user questions. i am building tiles and overviews for
> a tiff-file
> 
> #Tiles
> gdal_translate -co "TILED=YES" image_in.tif image_out.tif
> #Overviews
> gdaladdo -r average image_out.tif 2 4 8 16
> 
> now my questions:
> 1) has the order of the operations an influence to the result. it seems
> that the tiling command destroys the overviews

Christian,

Yes, order matters.  The gdal_translate command does not carry along overviews.

> 2) is there any possibility to identify if a tiff-file has inner tiling
> sets. i don't see any difference with gdalinfo

The gdalinfo command will report the block size in the band information.
For instance, a 512x512 image I have reports:

Band 1 Block=512x16 Type=Byte, ColorInterp=Gray

Because the block is as wide as the image and not square it is likely that
this image as stripped, not tiled.  If the block size is not as wide as the
image or the blocks are square it is likely a tiled image.

You can also use the tiffinfo command for an authoritative report on whether
an image is tiled or not.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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