Details Ticket 2558


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Serial Number 2558
Subject GRASS is messing up Robinson projection
Area bug
Queue grass
Requestors kyngchaos@charter.net
Owner none
Status open
Last User Contact Fri Jul 22 21:05:07 2005 (3 yr ago)
Current Priority 30
Final Priority 70
Due No date assigned
Last Action Fri Jul 22 21:05:07 2005 (3 yr ago)
Created Mon Jul 26 18:57:08 2004 (4 yr ago)

Transaction History Ticket 2558


Mon, Jul 26 2004 18:57:08    Request created by guest  
Subject: GRASS is messing up Robinson projection

grass binary for platform: Compiled from Sources
GRASS Version: CVS 2004-7-24

When using an external PROJ 4.4.8, GRASS is shifting the coordinates for the
Robinson projection.  
Along the equator and the poles there is no shift.  But at mid latitudes, everything
is shifted approx. 
20000m vertically (no x-shift) towards the equator.  Moving towards the poles
or the equator the 
shift decreases.  The same happens in the inverse (from Robinson), except that
the shift is towards 
the poles.

I've checked with the PROJ lib proj command and it does a correct projection
and inverse projection.  
But with GRASS m.proj2 (in 5.3) and r.proj and v.proj (both 5.3 and 5.7), everything
is shifted.

When the previous proj - 4.4.7 - is installed, GRASS projects to and from Robinson
just fine.
Tue, Aug 17 2004 10:33:19    Mail sent by guest  
Maybe interesting reading:

TI: Numerical Evaluation of the Robinson Projection
AU: Cengizhan Ipbuker
JN: Cartography and Geographic Information Science
PD: 1 April 2004
VO: 31
NO: 2
PG: 79-88(10)
PB: Cartography and Geographic Information Society
IS: 1523-0406
URL:
http://www.ingentaselect.com/rpsv/cgi-bin/cgi?body=linker&reqidx=1523-0406(20040401)31:2L.79;1-
Markus
Sat, Aug 28 2004 19:30:53    Comments added by guest  
Just thought to check on this bug and noticed the comment (didn't receive a notice
of the comment).  
I don't have access to the article - what's the gist of it?  How does it pertain
to this bug (does it make 
it a non-bug)?  Has anyone looked yet as to why GRASS might interact differently
with proj 4.4.7 and 
4.4.8 (since both internally seem to produce the same results)?

I've done a few other tests - the proj 4.4.7 Robinson matches Geocart (an old
Mac program) and 
MAPublisher 5 (Illustrator 10 plugin).

-kyngchaos@charter.net
Fri, Nov 5 2004 21:59:56    Comments added by guest  
I finally had a chance to test this with the new proj 4.4.9 and the problem is
still there.  Looks like 
I'm still keeping 4.4.7 around for a while for any Robinson work.

-kyngchaos@charter.net
Fri, Nov 5 2004 22:32:02    Comments added by guest  
Argh - now there's a compatibility version problem.  If grass is built with proj
4.4.9 (compatibility 
version 6.0.0), it won't use proj 4.4.7 (c.v. 5.0.0) if that's installed after
grass.  Must build grass with 
proj 4.4.7 installed if I want to be able to use it for the Robinson projection.
-kyngchaos@charter.net
Mon, Nov 29 2004 22:23:46    Mail sent by kyngchaos@charter.net  
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From William Kyngesburye <kyngchaos@charter.net>
Subject Re: [GRASS5] [bug #2558] (grass) GRASS is messing up Robinson projection
Date Mon, 29 Nov 2004 15:23:39 -0600
To Request Tracker <grass-bugs@intevation.de>
X-Mailer Apple Mail (2.619)
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Just wondering if/when some will have a chance to look into this.  As 
mentioned it's still a problem with proj 4.4.9.  And still with the 
current 5.7 CVS (probably 5.3/5.4 as well).  Also, the compatibility 
version difference is annoying - I forget to build a new grass cvs with 
proj 4.4.7 installed until I run thru a projection and discover it's 
wrong again.

I also discovered that it happens in the Transverse Cylindrical Equal 
area projection.  In a region centered around 41 deg, everything is 
shifted 20km towards to equator.  Don't know about at the equator or 
poles - it's a small region.  Installed proj 4.4.7 (same grass) and 
it's good.

I wonder what other projections have the problem...

-----
William Kyngesburye <kyngchaos@charter.net>
http://webpages.charter.net/kyngchaos/

"I ache, therefore I am.  Or in my case - I am, therefore I ache."

- Marvin


Wed, Jul 20 2005 00:09:07    Mail sent by mneteler  
Hi,

maybe Paul has an idea...

Markus
Wed, Jul 20 2005 00:25:41    Mail sent by pkelly  
I would need co-ordinate system information files (PROJ_INFO) for the two 
locations and a test point with expected and wrong results to do some initial
testing.

I see you say the proj and invproj commands give correct results---I wonder 
would it be possible to reproduce the bug with the cs2cs command as this uses
the same PROJ API functions as GRASS does?

Paul
Wed, Jul 20 2005 01:16:44    Mail sent by kyngchaos@kyngchaos.com  
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From William Kyngesburye <kyngchaos@charter.net>
Subject [bug #2558] (grass) GRASS is messing up Robinson projection
Date Tue, 19 Jul 2005 18:16:39 -0500
To Paul Kelly via RT <grass-bugs@intevation.de>
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Not sure if I can send attachments to the tracker, so there's links  
to my website so the examples.

Lat-long vector grid lines every 5 degrees, WGS84:

<http://www.kyngchaos.com/macosx/junk/world.zip>

Robinson, WGS84, projected with current PROJ.4 v4.4.9 in GRASS 6.1  
CVS (05-6-18):

<http://www.kyngchaos.com/macosx/junk/robin0.zip>

It's currently zoomed to the 0 deg long, 45 deg lat intersection.   
d.where at that location reads (approx):

0, 4784591.67


 From proj CLI tool:

proj +proj=robin +ellps=WGS84
0 0
0.00    0.00
0 45
0.00    4805073.65
0 90
0.00    8625154.47


-----
William Kyngesburye <kyngchaos@kyngchaos.com>
http://www.kyngchaos.com/

First Pogril: Why is life like sticking your head in a bucket filled  
with hyena offal?
Second Pogril: I don't know.  Why IS life like sticking your head in  
a bucket filled with hyena offal?
First Pogril: I don't know either.  Wretched, isn't it?

-HitchHiker's Guide to the Galaxy


Fri, Jul 22 2005 09:36:07    Mail sent by pkelly  
paul@bullseye:~$ echo "0 45" | proj +proj=robin \ 
+ellps=WGS84                    
0.00    4805073.65
paul@bullseye:~$ echo "0 45" | cs2cs +proj=longlat +ellps=WGS84 +to\ 
+proj=robin +ellps=WGS84
0.00    4785120.02 -10647.46

Suggests the problem is in PROJ, not GRASS. But if I have some time I will 
try and investigate where in PROJ the problem is. You might like to bring it
up in the PROJ bugtracker or mailing list though.

Paul
Fri, Jul 22 2005 21:05:07    Mail sent by kyngchaos@kyngchaos.com  
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From William Kyngesburye <kyngchaos@kyngchaos.com>
Subject Re: [bug #2558] (grass) GRASS is messing up Robinson projection
Date Fri, 22 Jul 2005 14:04:44 -0500
To Paul Kelly via RT <grass-bugs@intevation.de>
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Ah, I never thought to check cs2cs - I've never used that.

Makes me wonder now which is right.  I have checked with the  
MAPublisher extension to Illustrator, it produces the same result as  
proj.  I had issues with Robinson in Arc 8.2 once, haven't tried in  
9, so I don't know which way Arc leans.


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