Hi,
GeoTIFFs exported with r.out.gdal appear blank in QGIS 0.8 [1]. I have
reported that into QGIS bug tracker [1] supposing it was QGIS fault,
but I was told that:
"The tiff has a GRASS color table that is zero. See: $ gdalinfo
vegcover.tif | grep COLOR"
QGIS developers have hacked in a workaround for this issue. However, is
there anything which could be done in r.out.gdal to fix it at it's
roots? Or is a problem in GDAL maybe? Thanks for any hints.
Maciek
Maciej Sieczka wrote:
Hi,
GeoTIFFs exported with r.out.gdal appear blank in QGIS 0.8 [1]. I have
reported that into QGIS bug tracker [1] supposing it was QGIS fault,
but I was told that:"The tiff has a GRASS color table that is zero. See: $ gdalinfo
vegcover.tif | grep COLOR"QGIS developers have hacked in a workaround for this issue. However, is
there anything which could be done in r.out.gdal to fix it at it's
roots? Or is a problem in GDAL maybe? Thanks for any hints.
Did you specify type=Byte or type=UInt16? The default for CELL maps is
Int32, and a 2^32 entry palette isn't feasible.
$ r.out.gdal vegcover format=GTiff output=vegcover.tif
ERROR 6: SetColorTable() only supported for Byte or UInt16 bands in TIFF format.
Done!
[gdalinfo shows no colour table.]
$ r.out.gdal vegcover format=GTiff output=vegcover.tif type=Byte
Done!
[gdalinfo shows a colour table.]
Even with type=, the COLOR_TABLE_RULE* values are bogus; all entries
have zero for start, end and intensities:
COLOR_TABLE_RULES_COUNT=6
COLOR_TABLE_RULE_RGB_0=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_1=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_2=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_3=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_4=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_5=0.000000e+00 0.000000e+00 0 0 0 0 0 0
This is because:
1. vegcover doesn't use colour rules but a fixed palette:
#0 first color
255 255 255
0
255 0 0
255 255 0
255 128 0
0 0 255
255 0 255
0 255 0
[spearfish57/PERMANENT/colr/vegcover]
2. r.out.gdal is using the maximum value as the number of rules (hence
the COLOR_TABLE_RULES_COUNT=6) rather than the value returned by
G_colors_count().
I've committed a fix for point #2, so vegcover.tif won't have
COLOR_TABLE_RULES_COUNT or COLOR_TABLE_RULE_RGB_* tags.
--
Glynn Clements <glynn@gclements.plus.com>
Glynn Clements wrote:
Maciej Sieczka wrote:
GeoTIFFs exported with r.out.gdal appear blank in QGIS 0.8 [1].
Did you specify type=Byte or type=UInt16?
On https://svn.qgis.org/trac/ticket/643 you can read it was:
r.out.gdal input=vegcover format=GTiff type=Byte output=vegcover.tif
The default for CELL maps is
Int32, and a 2^32 entry palette isn't feasible.$ r.out.gdal vegcover format=GTiff output=vegcover.tif
ERROR 6: SetColorTable() only supported for Byte or UInt16 bands in TIFF format.
Done![gdalinfo shows no colour table.]
$ r.out.gdal vegcover format=GTiff output=vegcover.tif type=Byte
Done![gdalinfo shows a colour table.]
Even with type=, the COLOR_TABLE_RULE* values are bogus; all entries
have zero for start, end and intensities:COLOR_TABLE_RULES_COUNT=6
COLOR_TABLE_RULE_RGB_0=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_1=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_2=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_3=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_4=0.000000e+00 0.000000e+00 0 0 0 0 0 0
COLOR_TABLE_RULE_RGB_5=0.000000e+00 0.000000e+00 0 0 0 0 0 0This is because:
1. vegcover doesn't use colour rules but a fixed palette:
#0 first color
255 255 255
0
255 0 0
255 255 0
255 128 0
0 0 255
255 0 255
0 255 0[spearfish57/PERMANENT/colr/vegcover]
2. r.out.gdal is using the maximum value as the number of rules (hence
the COLOR_TABLE_RULES_COUNT=6) rather than the value returned by
G_colors_count().I've committed a fix for point #2, so vegcover.tif won't have
COLOR_TABLE_RULES_COUNT or COLOR_TABLE_RULE_RGB_* tags.
Thank you. I'll report back when I try the fixed version.
Regards,
Maciek