Hi,
trying to export some floating point map (result of interpolation) to
geotiff via gdal:
r.out.gdal in=ca2005 out=ca2005.tif type=Float32
result is, that the map is displayed as "black" e.g. in qgis and
mapserver is not able to display anything 
how to export floating point maps, so they can be read later by other programs
(which are using gdal too)?
when I import the map back
r.in.gdal in=ca2005.tif out=pokus, everything seems to be allright
:-(
Jachym
--
Jachym Cepicky
e-mail: jachym.cepicky@centrum.cz
URL: http://les-ejk.cz
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Jachym Cepicky wrote on 07/17/2006 03:43 PM:
Hi,
trying to export some floating point map (result of interpolation) to
geotiff via gdal:
r.out.gdal in=ca2005 out=ca2005.tif type=Float32
result is, that the map is displayed as "black" e.g. in qgis and
mapserver is not able to display anything
Jachym,
you could try to export to ERDAS/IMG format (format=HFA).
Maybe then the color tables is preserved.
Markus
how to export floating point maps, so they can be read later by other programs
(which are using gdal too)?
when I import the map back
r.in.gdal in=ca2005.tif out=pokus, everything seems to be allright
:-(
Jachym
Hi,
On Mon, Jul 17, 2006 at 04:24:12PM +0200, Markus Neteler wrote:
Jachym Cepicky wrote on 07/17/2006 03:43 PM:
> Hi,
> trying to export some floating point map (result of interpolation) to
> geotiff via gdal:
>
> r.out.gdal in=ca2005 out=ca2005.tif type=Float32
>
> result is, that the map is displayed as "black" e.g. in qgis and
> mapserver is not able to display anything
>
Jachym,
you could try to export to ERDAS/IMG format (format=HFA).
Maybe then the color tables is preserved.
Markus
hmm, problem is, that the map can not be displayed via mapserver - how
do you export any floting point geotiff ?
thanks
jachym
> how to export floating point maps, so they can be read later by other programs
> (which are using gdal too)?
>
> when I import the map back
>
> r.in.gdal in=ca2005.tif out=pokus, everything seems to be allright
>
>
> Jachym
>
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Jachym Cepicky
e-mail: jachym.cepicky@centrum.cz
URL: http://les-ejk.cz
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Tel.: +49 511-39088507
Jachym,
On 7/17/06, Jachym Cepicky <jachym.cepicky@centrum.cz> wrote:
> > trying to export some floating point map (result of interpolation) to
> > geotiff via gdal:
> >
> > r.out.gdal in=ca2005 out=ca2005.tif type=Float32
> >
> > result is, that the map is displayed as "black" e.g. in qgis and
> > mapserver is not able to display anything
> >
> Jachym,
>
> you could try to export to ERDAS/IMG format (format=HFA).
> Maybe then the color tables is preserved.
>
> Markus
hmm, problem is, that the map can not be displayed via mapserver - how
do you export any floting point geotiff ?
thanks
jachym
The r.out.gdal output *can* be displayed with mapserver but, since it
has no associated color palette (that mapserver can understand
anyhow), mapserver will render it in a black->white color ramp. If
your data values are very skewed, it may appear all black. Try using
the SCALE processing directive to set the min and max of the b&w color
ramp. (http://mapserver.gis.umn.edu/docs/howto/raster_data/#special-processing-directives)
Also, Have you tried r.out.tiff ? This will export a colored image of
your data at the current region settings. The resulting tiff will not
contain actual values but will look as it did in grass.
r.out.tiff -t input=elevation.dem output=elev
You can use the r.out.tiff output for display purposes and the
r.out.gdal output for query purposes.
Finally you might want to try reading the grass raster directly from
mapserver and avoid the conversion step altogether.
--
Matt Perry
perrygeo@gmail.com
http://www.perrygeo.net
thanks for hints
we will see
jachym
On Mon, Jul 17, 2006 at 10:41:17AM -0700, Matthew Perry wrote:
Jachym,
On 7/17/06, Jachym Cepicky <jachym.cepicky@centrum.cz> wrote:
>> > trying to export some floating point map (result of interpolation) to
>> > geotiff via gdal:
>> >
>> > r.out.gdal in=ca2005 out=ca2005.tif type=Float32
>> >
>> > result is, that the map is displayed as "black" e.g. in qgis and
>> > mapserver is not able to display anything
>> >
>> Jachym,
>>
>> you could try to export to ERDAS/IMG format (format=HFA).
>> Maybe then the color tables is preserved.
>>
>> Markus
>
>hmm, problem is, that the map can not be displayed via mapserver - how
>do you export any floting point geotiff ?
>
>thanks
> jachym
>
The r.out.gdal output *can* be displayed with mapserver but, since it
has no associated color palette (that mapserver can understand
anyhow), mapserver will render it in a black->white color ramp. If
your data values are very skewed, it may appear all black. Try using
the SCALE processing directive to set the min and max of the b&w color
ramp.
(http://mapserver.gis.umn.edu/docs/howto/raster_data/#special-processing-directives)
Also, Have you tried r.out.tiff ? This will export a colored image of
your data at the current region settings. The resulting tiff will not
contain actual values but will look as it did in grass.
r.out.tiff -t input=elevation.dem output=elev
You can use the r.out.tiff output for display purposes and the
r.out.gdal output for query purposes.
Finally you might want to try reading the grass raster directly from
mapserver and avoid the conversion step altogether.
--
Matt Perry
perrygeo@gmail.com
http://www.perrygeo.net
--
Jachym Cepicky
e-mail: jachym.cepicky@centrum.cz
URL: http://les-ejk.cz
GPG: http://les-ejk.cz/gnupg_public_key/jachym_cepicky-gpg_public_key.asc
-----------------------------------------
OFFICE:
GDF-Hannover
Mengendamm 16d
30177 Hannover
Germany
e-mail: cepicky@gdf-hannover.de
URL: http://gdf-hannover.de
Tel.: +49 511-39088507