Hi all.
Importing a dtm raster assign a correct colour table to it.
If I load it with r.external, instead, only a greyscale is applied. This happens through the qgis plugin, do not know if it's the same with other interfaces).
Is this a known issue?
All the best.
--
Paolo Cavallini
See: http://www.faunalia.it/pc
On Thu, Feb 23, 2012 at 12:03 PM, Paolo Cavallini <cavallini@faunalia.it> wrote:
Hi all.
Importing a dtm raster assign a correct colour table to it.
Which format do you have? For example, GeoTIFF has only limited color table
support.
If I load it with r.external, instead, only a greyscale is applied. This
happens through the qgis plugin, do not know if it's the same with other
interfaces).
Which operating system and which GRASS version?
Markus
Il 23/02/2012 14:04, Markus Neteler ha scritto:
On Thu, Feb 23, 2012 at 12:03 PM, Paolo Cavallini<cavallini@faunalia.it> wrote:
Hi all.
Importing a dtm raster assign a correct colour table to it.Which format do you have? For example, GeoTIFF has only limited color table
support.
adf (the same raster when imported has its nice colormap).
Which operating system and which GRASS version?
Debian testing, official package: 6.4.1-2
Thanks.
--
Paolo Cavallini
See: http://www.faunalia.it/pc
On Thu, Feb 23, 2012 at 12:03 PM, Paolo Cavallini <cavallini@faunalia.it> wrote:
Hi all.
Importing a dtm raster assign a correct colour table to it.
If I load it with r.external, instead, only a greyscale is applied.
Do you use r.colors?
This happens through the qgis plugin, do not know if it's the same with other
interfaces).
Is this a known issue?
I tried in GRASS:
# quick and dirty test:
GRASS 6.4.3svn (latlong_wgs84):~/data/maps/fao_forest_fra2000/frst_gez
r.external /home/neteler/data/maps/fao_forest_fra2000/frst_gez/w001001.adf
out=test
WARNING: Datum <Not_specified_based_on_Clarke_1866_ellipsoid> not
recognised by GRASS and no parameters found
Projection of input dataset and current location appear to match
Importing band 1 of 1...
Link to raster map <test> created
GRASS 6.4.3svn (latlong_wgs84):~/ > g.region rast=test -p
projection: 3 (Latitude-Longitude)
zone: 0
datum: wgs84
ellipsoid: wgs84
north: 90N
south: 90S
west: 180W
east: 180E
nsres: 0:00:32.4
ewres: 0:00:32.4
rows: 20000
cols: 40000
cells: 800000000
GRASS 6.4.3svn (latlong_wgs84):~/ > r.colors test col=gyr
Color table for raster map <test> set to 'gyr'
GRASS 6.4.3svn (latlong_wgs84):~/ > d.mon x0
GRASS 6.4.3svn (latlong_wgs84):~/> d.rast test
The map is nicely colorized.
I did not try in QGIS.
Markus
Il 23/02/2012 14:57, Markus Neteler ha scritto:
On Thu, Feb 23, 2012 at 12:03 PM, Paolo Cavallini<cavallini@faunalia.it> wrote:
Hi all.
Importing a dtm raster assign a correct colour table to it.
If I load it with r.external, instead, only a greyscale is applied.Do you use r.colors?
This happens through the qgis plugin, do not know if it's the same with other
interfaces).
Is this a known issue?I tried in GRASS:
# quick and dirty test:
GRASS 6.4.3svn (latlong_wgs84):~/data/maps/fao_forest_fra2000/frst_gez
Sorry I was unclear: importing the map results in an automatically nicely coloured map, whereas r.external results in a greyscale. Apparently r.in.gdal applies automatically an appropriated colour map, r.external does not.
All the best.
--
Paolo Cavallini
See: http://www.faunalia.it/pc
On Fri, Feb 24, 2012 at 7:15 AM, Paolo Cavallini <cavallini@faunalia.it> wrote:
Sorry I was unclear: importing the map results in an automatically nicely
coloured map, whereas r.external results in a greyscale.
Ah, this is a different issue then.
Apparently r.in.gdal applies automatically an appropriated colour map, r.external does
not.
GRASS, in case that no color table is present, applies the rainbow color table.
Probably r.external is presetting instead a grey-scale color table?
In any case quickly solvable with r.colors to apply one of the nice predefined
color tables.
Markus
Paolo wrote:
> Sorry I was unclear: importing the map results in an automatically
> nicely coloured map, whereas r.external results in a greyscale.
Markus N wrote:
Probably r.external is presetting instead a grey-scale color
table?
yes, it is doing that, see main.c line ~ 340.
if gdal supplies a color table it uses it, otherwise r.external checks
if the map is type GDT_Byte and if so applies the grey255 rules. Or, if
some other data type applies G_make_grey_scale_colors() based on the
range. I would suggest that this be changed to not create any color table
if none is provided. (and so act like other grass modules do in that
case and fall back to rainbow rules)
Hamish
On Fri, Feb 24, 2012 at 9:24 AM, Hamish <hamish_b@yahoo.com> wrote:
Paolo wrote:
> Sorry I was unclear: importing the map results in an automatically
> nicely coloured map, whereas r.external results in a greyscale.Markus N wrote:
Probably r.external is presetting instead a grey-scale color
table?yes, it is doing that, see main.c line ~ 340.
if gdal supplies a color table it uses it, otherwise r.external checks
if the map is type GDT_Byte and if so applies the grey255 rules. Or, if
some other data type applies G_make_grey_scale_colors() based on the
range. I would suggest that this be changed to not create any color table
if none is provided. (and so act like other grass modules do in that
case and fall back to rainbow rules)
+1 (then it becomes again the "least surprise" approach)
Markus
Il 24/02/2012 09:24, Hamish ha scritto:
yes, it is doing that, see main.c line ~ 340.
if gdal supplies a color table it uses it, otherwise r.external checks
if the map is type GDT_Byte and if so applies the grey255 rules. Or, if
some other data type applies G_make_grey_scale_colors() based on the
range. I would suggest that this be changed to not create any color table
if none is provided. (and so act like other grass modules do in that
case and fall back to rainbow rules)
ok, thanks a lot for clarifying.
all the best.
--
Paolo Cavallini
See: http://www.faunalia.it/pc
Hamish wrote:
if gdal supplies a color table it uses it, otherwise r.external checks
if the map is type GDT_Byte and if so applies the grey255 rules. Or, if
some other data type applies G_make_grey_scale_colors() based on the
range. I would suggest that this be changed to not create any color table
if none is provided. (and so act like other grass modules do in that
case and fall back to rainbow rules)
Note that r.in.gdal behaves similarly: if the input file lacks a
colour table, it creates a 0..255 grey-scale table for GDT_Byte, and a
range-based grey-scale table for GDT_UInt16.
It may be desirable to keep the two consistent. OTOH, r.in.gdal has a
longer history than r.external (i.e. it's more likely that someone is
relying upon the existing behaviour of r.in.gdal than is the case for
r.external).
--
Glynn Clements <glynn@gclements.plus.com>