Display GeoTIFF-data (>8bit) with the Mapserver

[Wolfgang Qual]

Hello Frank,
thanks very much for your idea: works fine! I did not have to reorder
the colors, just typed in

gdal_translate -scale -ot Byte [input_file] [output_file]

Before, I did the same, but just without the "-scale" option, and the
result were these strange colors..

Wolfgang

--

Frank Warmerdam schrieb:

> On Wed, 30 Mar 2005 14:18:01 +0200, Wolfgang Qual
> <Wolfgang.Qual at muenchen.de> wrote:
>
>>We purchased IKONOS-Satellite images (data format GeoTIFF, 16bit) and
>>would like to get it into a mapserver map. However, this data is not
>>supported by the mapserver. We got the error message:
>>"drawTIFF(): Image handling error. Only 1, 4, and 8-bit images are
>>supported."
>>Tried to make a 8bit GeoTIFF of it using the gdal-utility rgb2pct.py,
>>but it just produced strange results (strange colors).
>
>
> Wolfgang,
>
> I would suggest you first use gdal_translate to convert the data
> to 8bit with scaling.  Something like this should do the trick:
>
>   gdal_translate -scale -ot Byte ikonos_in.tif ikonos_out.tif
>
> Depending on the form you got your dataset, you may also find
> you want to reorder the bands for more normal viewing.  I believe
> some datasets are distributed in BGRN format (blue, green, red, near-ir).
> If you have that the colors will be pretty odd, but organizing it as
> RGB may help:
>
> eg.
>
>   gdal_translate -scale -ot Byte -b 3 -b 2 -b 1 bgrn.tif rgb.tif
>
> You may need to review your metadata to see what bands you have.
>
> Once you have scaled to 3 8bit bands and are happy with the result you can
> convert to pseudocolored format with rgb2pct.py if you wish.
>
>
>>Anybody there, who managed it to put such data into a mapserver map? How
>>can I produce a nice 8-bit image of the data without losing the
>>information of the satellite image?
>
>
> I would add that it seems your MapServer was built without GDAL support.
> If you build in GDAL support, you can directly render from the IKONOS
> files.  You will need to scale your data still but MapServer can do this
> for you.  You can also reorder the data.  Something like:
>
>   LAYER
>       NAME IKONOS
>       DATA mydatafile.tif
>       PROCESSING "SCALE=AUTO"
>       PROCESSING "BANDS=3,2,1"
>   END
>
> You may find you want an RGB output format like PNG24 or JPEG
> to get decent color results.
>
> Best regards,
> --
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent
>

--
Wolfgang Qual
Landeshauptstadt München
Referat für Gesundheit und Umwelt
RGU-UW 11
Sg. 1 Gesundheits- und Umweltberichterstattung,
Energie und Klimaschutz
Bayerstr. 28a, 80335 München
Tel.: +49 (0)89 233-477 17
Fax.: +49 (0)89 233-477 05
E-Mail: wolfgang.qual at muenchen.de