[GRASS-user] Creating a png file with multiple vector maps

[Chris Bartolomei]

 Hi Anna - thank you for the suggestion - I tried it but alas, still it only outputs a single vector map (layer). I can get either the Country vector or the admin_areas vector, but not both overlaid.:(Chris

    On Tuesday, February 9, 2021, 1:20:52 PM EST, Anna Petrášová <kratochanna at gmail.com> wrote:  
 
 Hi,
On Tue, Feb 9, 2021 at 10:25 AM Chris Bartolomei via grass-user <grass-user at lists.osgeo.org> wrote:

Good morning :)I'm using GRASS 7.4.1 on a Linux cluster so I only have command-line capability. I have two vector layers (a country boundary polygon and part of an administrative area map - also polygons). I am trying to automate creating a PNG file of the admin areas overlaying the country boundary therefore all work has to be command-line (in a bash script). I've tried this two ways - using the d.mon start=png method and also the ps.map method as described below. The d.mon method appears to generate the image with only one vector map (not both) and only colors the borders - it won't use the fill_color setting. The ps.map method seems to work but assumes the image is on a sheet of paper so there's a ton of extra white-space. I'd like to use d.mon but I can use ps.map if someone could please let me know how to export only the computational region without all the extra 'paper' in the image. Here's my code:
g.region vector='Country'export GRASS_RENDER_IMMEDIATE=pngexport GRASS_RENDER_WIDTH=640export GRASS_RENDER_HEIGHT=480export GRASS_RENDER_TRANSPARENT=trueexport GRASS_RENDER_TRUECOLOR=trueexport GRASS_RENDER_FILE=$HOME/country_admin.pngexport GRASS_RENDER_FILE_COMPRESSION=0export GRASS_MESSAGE_FORMAT=plaind.mon start=pngd.vect map=Country color=210:210:210 fill_color=153:153:153 display=shape type=aread.vect map=admin_area color=153:153:153 rgb_column=area_color display=shape type=aread.mon stop=png
This only produces a png with the last vector listed and only the borders are colored with the rgb_column values.

I think you are missing  GRASS_RENDER_FILE_READ=TRUE:https://grass.osgeo.org/grass78/manuals/pngdriver.html

Regarding rgb_column, I am not sure, didn't have time to test.
Anna

If I do this without the d.mon start/stop lines ... i.e. relying on the GRASS_RENDER_IMMEDIATE=png only, then only one vector map is converted to png however it DOES do the color fill properly. With either above method the png is the correct size.
Now using ps.map (same env variable set as above):
g.region vector='Country'
ps.map input=$HOME/ps_rules.txt out=$HOME/country_admin.ps --overwrite 
  where ps_rules.txt is:border y  color 81:81:81  endvareas admin_area  layer 1  rgbcolumn area_color  color 153:153:153  endvareas Country  color 210:210:210  fcolor 153:153:153  end
We don't have pstopng but we do have ghostscript:
gs-dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dTextAlphaBits=4 -dGraphicsAlphaBits=4 -r300 -sOutputFile=$HOME/country_admin.png $HOME/country_admin.ps
This creates the correct image (color fills, etc) but has white margins and a lot of white space below the image like it is printed at the top of a piece of paper.
does anyone have any idea how to create a png with multiple vector maps overlaying each other (and not have the extra whitespace too)?
v/rChris
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