[GRASS-user] Display output question

[Michael Barton]

On Feb 18, 2009, at 7:55 AM, <grass-user-request at lists.osgeo.org> wrote:

> Date: Wed, 18 Feb 2009 11:40:43 +0100
> From: Moritz Lennert <mlennert at club.worldonline.be>
> Subject: Re: [GRASS-user] Display output question
> To: grass-user at lists.osgeo.org
> Message-ID: <499BE5AB.4060907 at club.worldonline.be>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 17/02/09 02:42, Michael Barton wrote:
>>
>>
>> On Feb 16, 2009, at 6:34 PM, <grass-user-request at lists.osgeo.org>  
>> wrote:
>>
>>> Date: Tue, 17 Feb 2009 10:40:52 +1100
>>> From: Richard Chirgwin <rchirgwin at ozemail.com.au>
>>> Subject: [GRASS-user] Display output question
>>> To: GRASS user list <grass-user at lists.osgeo.org>
>>> Message-ID: <4999F984.9060605 at ozemail.com.au>
>>> Content-Type: text/plain; charset=ISO-8859-1
>>>
>>> Hi all,
>>>
>>> What's the command-line equivalent to using the JPG export in the
>>> display manager? (I would like to script outputs from a number of
>>> workspace - GRC - files).
>>>
>>> Cheers,
>>> Richard
>>
>> What happens in TclTk is that the display output is set to a PPM file
>> instead of monitor. Then any d.* command creates a graphic file. The
>> display graphic file is then converted to a jpeg. The latter can be  
>> done
>> by a variety of programs, including gdal-translate.
>>
>> In wxPython, the display can be saved in a number of different  
>> formats
>> using wxPython drivers.
>
>
> Yes, but AFAIK, you cannot easily use the contents of a .grc or .gxw
> file for scripting. You would have to parse the file with relevant  
> tools
> (awk, sed or an xml parser for gxw) and then apply these options to  
> the
> d.* commands using the cairo or PNG "monitor" to create a PNG file.
>
> In the TclTk GUI, you could save the content of the Output window  
> after
> having displayed your workspace and filter out the d.* commands. In  
> the
> wxGUI this is not possible anymore, AFAICT.
>
> It might be worth thinking about a module that translates workspace
> files into d.* commands...
>
> Moritz

If you want to replicate a complex display with overlaying maps it is  
more complicated than this even. The maps need to be composited. We  
use g.pnmcomp. The input is a series of PNM maps and optionally their  
transparency masks; the output is a single, composite PNM file. I  
assumed (incorrectly perhaps?) that Richard was asking how to send a  
d.* output to a file instead of a display. Glynn has discussed adding  
an output argument to d.* commands for GRASS 7 to make this easier for  
scripting and command line work. AFAICT, this is not yet implemented.

Michael