[gdal-dev] Re: gdal_retile and nodata

christian.mueller at nvoe.at christian.mueller at nvoe.at
Fri May 21 10:38:03 EDT 2010

Any new tile is created according to the create options "-co  
Name=value" you can pass in as parameter.

First an image is created, larege enough to hold the tile and its  
neighbors from level x-1

Second , the tiles from level x-1 are painted onto this image.

Third, the scaling takes place.

Fourth, I crop the interesting part for level x

The problem is, sometimes neighbors are missing, right ?

Do you have this problem already at level 1 or beginning with level 2 ?

Do you start from one big image or an already tiled image ?

Quoting acangi <aca at ngi.be>:

> I ran gdal_retile on a smaller set of data (same data with nodata values) so
> I already have a result. You can see the border on the picture. In GeoServer
> I set the outputTransparentColor to #000000.
> I don't think my problem comes from the existing nodata values in the source
> files, but rather from non-existing tiles at level x-1, when generating
> level x. There is a gap at level x-1 and gdal_retile has to write data at
> level x. What data is it supposed to write when there is no tile covering
> this location at level x-1 ?
> http://n2.nabble.com/file/n5084464/nearblack_border.png
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