[GRASS-user] Output question - ps.map

Hamish hamish_b at yahoo.com
Mon Jun 30 00:30:59 EDT 2008

Richard Chirgwin wrote:
> I need to produce postscript output maps with sufficient resolution
> that when I drill down on the output image, it doesn't turn to
> pixellation.
> I know that my input vectors are okay at high zoom levels; and I try
> to set high region resolution using g.region. But I still have
> low resolution outputs.

ps.map in newer versions of GRASS will render rasters at the region resolution. So check "g.region -p". Beware it will happily let you make 150mb+ PostScript files which your printer may or may not strugle with.

for an A4 piece of paper to get 300dpi: figuring 7" width after margins, that's 2100 x yyyy  columns x rows. I don't think there' much point going higher than 300dpi. earlier version of GRASS locked you into a max of 72(??)dpi. (or 90? can't remember)

For me, I mostly ignore the 300dpi calc and for little justified reason try to keep the file size at about 25mb for an A4 plot. Looks fine.

also note if you convert to PDF (I use ps2pdf13 for that) that it may reduce itself to a 72dpi JPEG, and there's not much that can be done about that, or if there is I haven't found out how. And here's an opportunity for me to plug the very handy "pdftk" command line PDF toolkit swiss-army knife software. It rocks.



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