Feature request #3127

support GRASS color rules

Added by hamish - over 6 years ago. Updated over 4 years ago.

Status:Open Start Date:
Priority:Low Due date:
Assigned to:- % Done:


Target version:Future Release - Nice to have
Platform:All Resolution:
Platform version: Pull Request or Patch supplied:No
Status info:0 Tag:


I see qgis has just got some better graduated symbol/color improvements,
great! that's been lacking for a long time. Compared to that GRASS's
r.colors and v.colors modules are so much more powerful, so until qgis
has better raster+vector color support I'd like to set those in GRASS
and have QGIS be able to read the color rules from GRASS exported geotiffs
and shapefiles. (the people I deliver maps to often run qgis but not grass)

vector: (mostly shapefiles)
- it would be great if the point icon's or line's color could be read from
an attribute column containing a R:G:B string (0-255). In GRASS see d.vect
+ GRASSRGB column (but the column can be called anything). that way you
could use v.colors (qgis grass toolbox) to set more powerful color

- When a GeoTiff is exported from GRASS with r.out.gdal, the first 1000
lines of the color rules file (usually there is less than 10) is written
to the GeoTiff metadata as "COLOR_TABLE_RULE_RGB_n" where "n" starts at
1 and goes up. the rest of the line looks like:
min max R1 G1 B1 R2 G2 B2
with RGB values for the min and max within that range. colors for values
in between that step are linearly interpolated between R1,R2 etc.
Also the new GDAL version seems to be making filename.tif.aux.xml too,
which contains those COLOR_TABLE_RULE_RGB_1,2,3,... rules.

the long term idea would be for many OSGeo projects to share a common
color formats for these things, so data can be more easily shared.
(for what it's worth, GMT and GRASS already are very similar for some
things like this, I think it has to do with common code ancestry 15+ years
ago, and partly ending up with common solutions after years of trying
different methods)

(working on a common .svg icon/symbol pool is another idea along these lines.)



Updated by Markus Neteler over 6 years ago

See also #782

Updated by Giovanni Manghi over 5 years ago

  • Target version changed from Version 1.7.0 to Version 1.7.4

Updated by Paolo Cavallini over 5 years ago

  • Assigned to deleted (Lorenzo Masini)
  • Pull Request or Patch supplied set to No

Updated by Giovanni Manghi almost 5 years ago

  • Target version changed from Version 1.7.4 to Version 2.0.0

Updated by Pirmin Kalberer over 4 years ago

  • Target version changed from Version 2.0.0 to Future Release - Nice to have

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