Details Ticket 2423


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Serial Number 2423
Subject ps.map raster drawing filesize
Area wish
Queue grass
Requestors hamish_nospam@yahoo.com
Owner none
Status open
Last User Contact Mon May 24 17:18:19 2004 (4 yr ago)
Current Priority 10
Final Priority 70
Due No date assigned
Last Action Fri Feb 9 07:32:28 2007 (2 yr ago)
Created Mon May 24 04:50:17 2004 (4 yr ago)

Transaction History Ticket 2423


Mon, May 24 2004 04:50:17    Request created by guest  
Subject: ps.map raster drawing filesize

Platform: GNU/Linux/i386
grass obtained from: Mirror of Trento site
grass binary for platform: Compiled from Sources
GRASS Version: 5.3 cvs may 2004

As it is, when ps.map draws a raster map all NULL cells are drawn with whatever
color they were given with r.colors (usually white). This is fine, but results
in the same PostScript filesize regardless of the number of NULLs in the map.
I have a 1400x2000 map which is only 3% non-NULL, but the filesize is still 20mb;
mostly FFFFFF's. Is it at least possible to replace a line of all NULLs with
a y_position++ type PS command, even if raster data must be written in blocks[*]?
or shrink the actual PS raster box to the outer bounds of the non-NULL data &
reposition?

My data is mostly on the diagonal covering all rows so neither of these solutions
would help my situation much, but maybe someone else?

[*] just a guess that it has to be this way


see  grass/src/ps.map/ps.map/cmd/rast_plot.c   ps_write_mask_row()


thanks,
Hamish
Mon, May 24 2004 17:18:19    Mail sent by glynn.clements@virgin.net  
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Date Mon, 24 May 2004 05:04:13 +0100
To Request Tracker <grass-bugs@intevation.de>
Cc grass5@grass.itc.it
Subject Re: [GRASS5] [bug #2423] (grass) ps.map raster drawing filesize
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Request Tracker wrote:

> this bug's URL: http://intevation.de/rt/webrt?serial_num=2423

> Subject: ps.map raster drawing filesize

> As it is, when ps.map draws a raster map all NULL cells are drawn with
> whatever color they were given with r.colors (usually white). This is
> fine, but results in the same PostScript filesize regardless of the
> number of NULLs in the map.
> 
> I have a 1400x2000 map which is only 3% non-NULL, but the filesize is
> still 20mb; mostly FFFFFF's. Is it at least possible to replace a line
> of all NULLs with a y_position++ type PS command, even if raster data
> must be written in blocks[*]?

It would probably be easier to replace the call to "readhexstring"
with a procedure which decodes e.g. run-length encoded data (and
encode the actual image data accordingly).

Otherwise, you would need a y_position+=dy type command, which means
that you have to figure out what dy should be.

> or shrink the actual PS raster box to
> the outer bounds of the non-NULL data & reposition?

That would be feasible.

> see  grass/src/ps.map/ps.map/cmd/rast_plot.c   ps_write_mask_row()

Yep. That's the file you need to change ;)

-- 
Glynn Clements <glynn.clements@virgin.net>


Fri, Feb 9 2007 07:32:28    Priority changed to 10 by hbowman  
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