[GRASS-user] editing grass postscript maps

[Tyler Smith]

On Thu, May 17, 2007 at 01:13:47AM +0100, Glynn Clements wrote:
> Next time, you might want to use "g.region res=" to reduce the size of
> the raster data. 100MB is ~16 million pixels @ 6 bytes/pixel (RRGGBB).
> 
> Looking at the "paper" command:
> 
>   width 2.73 inches
>   height 1.75 inches
> 
> 2.73 * 1.75 = 4.7775 sq.in.
> 100e6 / 6 = 16666667 pixels
> 16666667 / 4.7775 = 3488575 pixels/sq.in.
> sqrt(3488575) = 1868 pixels/in
> 
> 
> I doubt that there's much point in going above 300 DPI (around 1/6th
> of what you appear to have) for a raster; 2.73" * 1.75" @ 300 DPI
> would be 819 * 525.
> 

So, if g.region -p tells me:

nsres:      0:00:30.0024
ewres:      0:00:30.0024

To reduce the resolution by 1/6 I would do:

g.region res=0:03:00.0000

Is that right?

I'll give it a try...

Done!

My completed figure is now 16MB instead of 500MB, and it looks fine!
Wish I'd known about g.region res before -- next time it will be
much easier, and will take a lot less time and disk space.

Thanks,

Tyler

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