Details Ticket 3705


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Serial Number 3705
Subject ps.map resolution
Area grass6
Queue grass
Requestors Ian.MacMillan@pomona.edu
Owner none
Status resolved
Last User Contact Mon Apr 17 13:37:37 2006 (2 yr ago)
Current Priority 30
Final Priority 70
Due No date assigned
Last Action Fri Feb 9 05:28:50 2007 (2 yr ago)
Created Sat Oct 1 01:22:21 2005 (3 yr ago)

Transaction History Ticket 3705


Sat, Oct 1 2005 01:22:21    Request created by guest  
Subject: ps.map resolution

Platform: Mac OSX
grass obtained from: Other (CDROM etc)
grass binary for platform: Downloaded precompiled Binaries
GRASS Version: 6.1cvs 20050917

Hi all, there is a limit to the resolution with which a postscript can be rendered.
It is limited to 75 
dpi.  However many rasters are much finer resolution than this.  It would be
nice to be able to set the 
postscript to any scale we'd like, and have it print at the resolution of the
region.  Below is from the 
mailing list archive GRASSLIST 8404

Cheers,
Ian


Sorry, you're right; ps.map has a hardcoded limit of 75dpi. The
"scale" command changes the size of the image, and thus of the
computed resolution.

set_paper.c has a hardcoded setting:

    PS.res = 75;

This is used in map_setup.c to limit the size of a raster:

	if (PS.grey || PS.level == 1) limit = 300000000L;
	else limit = 100000000L;
    	while (num_cells > limit || cells_per_inch > PS.res)
    	{	
	    if (PS.cells_high >= PS.cells_wide)
            {   
	    	PS.cells_high /= 2;
	    	PS.ns_res *= 2.0;
	    	PS.row_delta++;
		cells_per_inch /= 2;
	    }
	    else
	    { 
	    	PS.cells_wide /= 2;
	    	PS.ew_res *= 2.0;
	    	PS.col_delta++;
		cells_per_inch /= 2;
	    }
    	    num_cells = (long)PS.cells_high * (long)PS.cells_wide;
    	}

Thus it effectively rescales the raster by powers of two until it is
less than 75dpi and contains less than 3E8 pixels for greyscale or 1E8
pixels for colour.

You may be able to get around the 75dpi limit by selecting a larger
paper size then rescaling it with psresize (from the psutils package).

Personally, I think that code should simply be removed. I suspect that
it was put there to prevent users from accidentally creating huge
print jobs on a system which couldn't handle them.

Note that the image is "streamed" (rendered as it is read from the
PostScript file, not stored), so the amount of memory in the printer
isn't an issue.
>
>
So it seems to me that the resolution is based on the region, and the 
output device that the postscript is written to.  The effective 
resolution of the raster in the postscript file does not necessarily 
equal that of the region.  My question is this, how does one get an 
effective resolution equal to that of my region in my final postscript 
file using ps.map?  Can I set up a fake output device with a really 
high resolution in Grass 6?
>
>
Use a larger paper size, or simply remove all references to PS.res
from ps.map.

Glynn Clements <glynn@gclements.plus.com>
Wed, Feb 22 2006 09:44:32    Mail sent by msieczka  
Ian,

Few days ago Glynn has removed the 75 DPI code from ps.map for good. Can you
retest and post an update? I wold appreciate a direct email to werchowyna at
epf dot pl so I'll know whether to close this one.

Best,
Maciek
Wed, Feb 22 2006 10:50:34    User changed to Ian.MacMillan@pomona.edu by msieczka  
Wed, Feb 22 2006 10:52:19    Mail sent by msieczka  
Ian,

Resending this and changing requestor adress to your current address as your
original email doesn't work anymore.

---

Few days ago Glynn has removed the 75 DPI code from ps.map for good. Can you
retest and post an update? I wold appreciate a direct email to werchowyna at
epf dot pl so I'll know whether to close this one.

Best,
Maciek
Wed, Feb 22 2006 18:25:53    Mail sent by Ian.MacMillan@pomona.edu  
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From Ian MacMillan <Ian.MacMillan@pomona.edu>
Subject Re: [bug #3705] (grass) ps.map resolution
Date Wed, 22 Feb 2006 09:21:55 -0800
To Maciek Sieczka via RT <grass-bugs@intevation.de>
X-Mailer Apple Mail (2.623)
X-OriginalArrivalTime 22 Feb 2006 17:21:14.0357 (UTC) FILETIME=[62029A50:01C637D4]
X-Spam-Status No, hits=-4.9 tagged_above=-999.0 required=3.0 tests=BAYES_00
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Maciek,

I'm a bit confused, what would you like me to do?  Do you need me to 
test the ps.map and see if it works?  Do I need to respond to the 
bugtracker?  I have changed email addresses because I have changed 
institutions, so I can't reply with the original email address.

Thanks,
Ian

On Feb 22, 2006, at 1:52 AM, Maciek Sieczka via RT wrote:

> Ian,
>
> Resending this and changing requestor adress to your current address 
> as your
> original email doesn't work anymore.
>
> ---
>
> Few days ago Glynn has removed the 75 DPI code from ps.map for good. 
> Can you
> retest and post an update? I wold appreciate a direct email to 
> werchowyna at
> epf dot pl so I'll know whether to close this one.
>
> Best,
> Maciek
>
>
> -------------------------------------------- Managed by Request Tracker
>
 >
 >
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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Mon, Apr 17 2006 13:37:37    Mail sent by msieczka  
Ian wrote:
> I'm a bit confused, what would you like me to do?  Do you need me to 
> test the ps.map and see if it works?  Do I need to respond to the 
> bugtracker?

Yes, if you can. Also, please CC me <werchowyna at epf dot pl> - otherwise I
will not be informed you replied to the tracker (yes it's a pain but Grass
bugtracker is like it is), so it might again take a month until I recheck this
ticket :).

> I have changed email addresses because I have changed 
> institutions, so I can't reply with the original email address.

That is not a problem. Use whatever address you like :). I was only letting
you know that I have updated your (bug requestor) email accordingly for this
ticket.

Best,
Maciek
Fri, Feb 9 2007 05:28:50    Status changed to resolved by hbowman  
Fri, Feb 9 2007 05:28:50    Comments added by hbowman  
this was fixed by Glynn a long time ago. Closing it.



Hamish
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