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

[Anna Petrášová]

On Tue, Feb 9, 2021 at 4:41 PM Chris Bartolomei <surfcjb at yahoo.com> wrote:

> 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
>

I realized you are using both environmental variables and d.mon, that might
cause some issues, you use one or the other. So try to remove the lines
starting with d.mon.

Hope that helps,
Anna

>
> 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=png
> export GRASS_RENDER_WIDTH=640
> export GRASS_RENDER_HEIGHT=480
> export GRASS_RENDER_TRANSPARENT=true
> export GRASS_RENDER_TRUECOLOR=true
> export GRASS_RENDER_FILE=$HOME/country_admin.png
> export GRASS_RENDER_FILE_COMPRESSION=0
> export GRASS_MESSAGE_FORMAT=plain
> d.mon start=png
> d.vect map=Country color=210:210:210 fill_color=153:153:153 display=shape
> type=area
> d.vect map=admin_area color=153:153:153 rgb_column=area_color
> display=shape type=area
> d.mon stop=png
>
> This only produces a png with the last vector listed and only the borders
> are colored with the rgb_column values.
>
>
> I think you are missing  GRASS_RENDER_FILE_READ=TRUE:
> https://grass.osgeo.org/grass78/manuals/pngdriver.html
>
> Regarding rgb_column, I am not sure, didn't have time to test.
>
> Anna
>
>
> If I do this without the d.mon start/stop lines ... i.e. relying on the
> GRASS_RENDER_IMMEDIATE=png only, then only one vector map is converted to
> png however it DOES do the color fill properly. With either above method
> the png is the correct size.
>
> Now using ps.map (same env variable set as above):
>
> g.region vector='Country'
> ps.map input=$HOME/ps_rules.txt out=$HOME/country_admin.ps --overwrite
>   where ps_rules.txt is:
> border y
>   color 81:81:81
>   end
> vareas admin_area
>   layer 1
>   rgbcolumn area_color
>   color 153:153:153
>   end
> vareas Country
>   color 210:210:210
>   fcolor 153:153:153
>   end
>
> We don't have pstopng but we do have ghostscript:
>
> gs-dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dTextAlphaBits=4
> -dGraphicsAlphaBits=4 -r300 -sOutputFile=$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/r
> Chris
>
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