[GRASSLIST:8399] Re: ps.map resolution

[Ian MacMillan]

Glynn, if I understand you correctly, the postscript file is written at 
the resolution of the region as long as that is coarser than the output 
device.  Otherwise, the file is written at the resolution of the output 
device.

If this is correct, is there a way that one could change the 
device/resolution using ps.map in Grass 6?

Thanks,
Ian



On Sep 23, 2005, at 9:43 AM, Glynn Clements wrote:

>
> Ian MacMillan wrote:
>
>> Hi all, I don't think this has been discussed on the mailing list
>> before, sorry if it has.  Is there any way to increase the resolution
>> of a raster using ps.map?
>>
>>   As near as I can tell, all rasters come out at 72 dpi.  My 
>> work-around
>> so far has been to use ps.map, then double, triple, or quadruple my
>> scale on a huge page, then use some other software to scale that back
>> down to increase the resolution of the raster within the postscript
>> file.  This gets cumbersome for large maps.
>>
>> One used to be able to mess around in $GISBASE/etc/paint/ps.devices so
>> that you could add or delete different paper sizes with their
>> resolutions I believe, but that is no longer an option it seems with
>> ps.map.  Looking at the paper.h file of the source, it seems that the
>> preset page sizes do not have a resolution option either.
>
> PostScript files are rendered at the resolution of the output device.
> For a printer, this will typically be between 300 and 1200 dpi; for a
> monitor it's usually between 75 and 120 dpi. If you render to an image
> file with Ghostscript, it will use whatver resolution you tell it to
> via the -r switch (IIRC, the default is 75 dpi).
>
> The raster which is embedded in the PostScript file will be generated
> using the region settings, so if your current region has a lower
> resolution than the raster itself, the resolution will be reduced.
>
> -- 
> Glynn Clements <glynn at gclements.plus.com>
>
 >
 >
What happens if a big asteroid hits Earth? Judging from realistic 
simulations involving a sledge hammer and a common laboratory frog, we 
can assume it will be pretty bad.
  - Dave Barry


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