[GRASS-user] How to define the png image dimensions when using d.mon?

[Moritz Lennert]

On 09/03/16 16:55, jean pierre huart wrote:
> Bingo! Thanks Moritz,
>
> - the existing file... I didn't care about it, convinced that the
> --overwrite parameter will wipe it out.

I agree that is a bit confusing (and could maybe be handled better), but 
--overwrite comes into action at the time of writing of the file, not at 
the time of reading the existing RENDER_FILE.

> Launching this script in a cron, I've the feeling that the use of
> GRASS_RENDER_IMMEDIATE is more appropriate. By the way, the choice is
> simple, this solution works fine for me, but using d.mon does not.

What does not work with d.mon ? Does my below script work for you (it 
uses the NC demo data set [1]) ?

Moritz

[1] https://grass.osgeo.org/download/sample-data/


>
> Ciao
>
> On 09/03/16 16:12, Moritz Lennert wrote:
>> On 09/03/16 15:39, jean pierre huart wrote:
>>> Thanks Vinay, for the suggestion but I get an error on the d.out.file
>>> instruction.
>>> By the way, I've investigated the problem a bit further and found that I
>>> mixed up instructions from manuals of different versions.
>>> So coming back to GRASS v 7.0.x references I finally succeed in
>>> obtaining a solution but not 100% satisfactory.
>>>
>>> First trial create a unique image combining raster and vector, but width
>>> and height remains at default and background is not transparent:
>>>
>>>       os.environ['GRASS_RENDER_TRANSPARENT'] = 'TRUE'
>>>       os.environ['GRASS_RENDER_WIDTH'] = str(1280)
>>>       os.environ['GRASS_RENDER_HEIGHT'] = str(960)
>>>       os.environ['GRASS_RENDER_FILE'] = filenameCombined.png
>>>
>>>       self.gscript.run_command('d.mon', overwrite=True, start='png',
>>> output=filename)
>>>       self.gscript.run_command('d.rast', map='{0}@{1}'.format(raster,
>>> currentmapset)
>>>       self.gscript.run_command('d.vect', map='{0}@{1}'.format(map,
>>> currentmapset), color='white', fill_color='none')
>>>       self.gscript.run_command('d.mon', stop="png")
>>>
>>>
>>> Second trial successfull for obtaining desired width, height and
>>> transparency of the background  but creating 2 images one for the raster
>>> and the other for the vector, now I would like to combine them to have
>>> only one image:
>>>
>>>       os.environ['GRASS_RENDER_IMMEDIATE'] = 'png'
>>>       os.environ['GRASS_RENDER_TRANSPARENT'] = 'TRUE'
>>>       os.environ['GRASS_RENDER_WIDTH'] = str(1280)
>>>       os.environ['GRASS_RENDER_HEIGHT'] = str(960)
>>>
>>>       os.environ['GRASS_RENDER_FILE'] = filenameOfRaster.png
>>>       self.gscript.run_command('d.rast', map='{0}@{1}'.format(raster,
>>> currentmapset))
>>>
>>>       os.environ['GRASS_RENDER_FILE'] = filenameOfVector.png
>>>       self.gscript.run_command('d.vect', map='{0}@{1}'.format(map,
>>> currentmapset), color='white', fill_color='none')
>>>
>>> Modifying this with the following
>>>
>>>       os.environ['GRASS_RENDER_FILE'] = filenameCombined.png
>>>       self.gscript.run_command('d.rast', map='{0}@{1}'.format(raster,
>>> currentmapset))
>>>       self.gscript.run_command('d.vect', map='{0}@{1}'.format(map,
>>> currentmapset), color='white', fill_color='none')
>>>
>>> ends with only the image of the vector.
>>>
>>> I've the feeling that using d.mon would be preferable, but it seems that
>>> it does not take into account the environment variables (at the
>>> exception of GRASS_RENDER_FILE) that I propose.
>>
>> This script gives me differently sized png files with both maps
>> displayed and transparent background:
>>
>> import grass.script as gscript
>> import os
>>
>> os.environ['GRASS_RENDER_TRANSPARENT']='TRUE'
>>
>> for height in range(500,2000,500):
>>      for width in range(500,2000,500):
>>
>>          os.system('rm map.png')
>>          os.environ['GRASS_RENDER_HEIGHT']=str(height)
>>          os.environ['GRASS_RENDER_WIDTH']=str(width)
>>
>>          gscript.run_command('d.mon', overwrite=True, start='png',
>> output='map.png')
>>          gscript.run_command('d.rast', map_='elevation')
>>          gscript.run_command('d.vect', map_='roadsmajor')
>>          gscript.run_command('d.mon', stop="png")
>>
>>          os.system('identify map.png')
>>
>>
>> You can reach the same result with something like this:
>>
>> import grass.script as gscript
>> import os
>>
>> os.environ['GRASS_RENDER_TRANSPARENT']='TRUE'
>>
>> for height in range(500,2000,500):
>>      for width in range(500,2000,500):
>>
>>          os.system('rm map.png')
>>          os.environ['GRASS_RENDER_IMMEDIATE']='png'
>>          os.environ['GRASS_RENDER_FILE']='map.png'
>>          os.environ['GRASS_RENDER_FILE_READ']='TRUE'
>>          os.environ['GRASS_RENDER_HEIGHT']=str(height)
>>          os.environ['GRASS_RENDER_WIDTH']=str(width)
>>
>>          gscript.run_command('d.rast', map_='elevation')
>>          gscript.run_command('d.vect', map_='roadsmajor')
>>
>>          os.system('identify map.png')
>>
>>
>> You might have to watch out for existing files. If a file already
>> exists with the indicated name then GRASS cannot change its width and
>> height.
>>
>> Hope this helps,
>> Moritz
>
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