[gdal-dev] Masking issue

[Oyvind Idland]

Hi Chaitanya,

thanks, i'll try that when I get back to it tomorrow.

But: I guess I will have to add -vrtnodata aswell, hopefully it will add
pixels to the mask ?

I have already converted all the source TIFFs to lossless compressed
GeoTiff (which don't
produce undesired JPEG artifacts), and made a VRT that tiles them together
using -vrtnodata
(suggestion from Michael Smith).

This works well, but having compression with JPEG + mask would be nice.
Some of the files
are still quite large (including gdaladdo overviews)

-- Oyvind



On Tue, Apr 3, 2012 at 7:35 PM, Chaitanya kumar CH
<chaitanya.ch at gmail.com>wrote:

> Oyvind,
>
> One easy method is to create a vrt file with an alpha band for the
> original tiff. You can use this to create a compressed raster file that
> will be
> transparent at nodata pixels.
>
> gdalbuildvrt -addalpha
>
> http://www.gdal.org/gdalbuildvrt.html
>
> On Tue, Apr 3, 2012 at 5:26 PM, Oyvind Idland <oyvind.idland at gmail.com>wrote:
>
>> Hello,
>>
>>
>> I got one problem: I have a bunch of uncompressed TIFF tiles, which I am
>> converting to compressed GeoTiff. I would
>> like to mask away the rgb(0,0,0) values.
>>
>> However, when I use NODATA on my VRT dataset, there are JPEG artifacts
>> around the edges when rendering.
>>
>> Is it possible to generate a transparency mask based on NDATA before
>> compressing, or is there any other/better way of
>> doing this ?
>>
>> thanks,
>>
>> - oyvind
>>
>>
>> _______________________________________________
>> gdal-dev mailing list
>> gdal-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>>
>
>
>
> --
> Best regards,
> Chaitanya kumar CH.
>
> +91-9494447584
> 17.2416N 80.1426E
>
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