Details Ticket 4028


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Serial Number 4028
Subject d.grid, pj_transform() failed: be more informative when error due to outside the transformation grid
Area wish6
Queue grass
Requestors david.p.finlayson@gmail.com
Owner none
Status open
Last User Contact Fri Jan 27 16:21:16 2006 (3 yr ago)
Current Priority 30
Final Priority 70
Due No date assigned
Last Action Fri Jan 27 16:21:16 2006 (3 yr ago)
Created Sat Jan 21 08:53:44 2006 (3 yr ago)

Transaction History Ticket 4028


Sat, Jan 21 2006 08:53:44    Request created by guest  
Subject: d.grid -g fails for Washington State Plane South Projection

Platform: GNU/Linux/x86
grass obtained from: CVS
grass binary for platform: Compiled from Sources
GRASS Version: 20060117

Problem: d.grid -g fails to draw a geographic grid in the Washington State Plane
South projection:

# Washington State Plane South:
GRASS 6.1.cvs (WASPS_NAD83):~/ecology_data_nad83_harn > g.proj -p
-PROJ_INFO-------------------------------------------------
name       : State Plane
datum      : nad83
nadgrids   : WO
proj       : lcc
a          : 0.6378137e+07
es         : 0.66943800229e-02
x_0        : 0.5e+06
y_0        : 0
lon_0      : 120d30'w
lat_0      : 45d20'n
lat_1      : 47d20'n
lat_2      : 45d50'n
-PROJ_UNITS------------------------------------------------
unit       : USfoot
units      : USfeet
meters     : 0.30480060960121920243

GRASS 6.1.cvs (WASPS_NAD83):~/ecology_data_nad83_harn > d.grid -g size=1 color=red
origin=0,0 bordercolor=blue
pj_transform() failed
cause: failed to load NAD27-83 correction file
ERROR: Error in pj_do_proj

d.grid -g works perfectly from Washington State Plane North (same projection
with the standard parallels shifted north):

# Washington State Plane North
GRASS 6.1.cvs (WASPN_NAD83):~ > g.proj -p
-PROJ_INFO-------------------------------------------------
name       : State Plane
datum      : nad83
nadgrids   : WO
proj       : lcc
a          : 0.6378137e+07
es         : 0.66943800229e-02
x_0        : 0.5e+06
y_0        : 0
lon_0      : 120d50'w
lat_0      : 47dn
lat_1      : 48d44'n
lat_2      : 47d30'n
-PROJ_UNITS------------------------------------------------
unit       : USfoot
units      : USfeet
meters     : 0.30480060960121920243

GRASS 6.1.cvs (WASPN_NAD83):~ > d.grid -g size=1 color=red origin=0,0
bordercolor=blue

(draws grid on screen)

To reproduce the error you need to create a washington state plane south location.
Select Projection: D (other projection)
projection: stp
datum: nad83
transformation: 5 (Washington - Oregon)
state FIPS code: 53 (WA)
county FIPS code: 67 (Thurston)
state plane: 83 (1983)
units: 1 (US Survey Foot)

north:      1383333.33333333
south:      -90000
west:       478678.67867868
east:       2681081.08108108
nsres:      303.03030303
ewres:      300.3003003
rows:       4862
cols:       7334

Now try to add the geographic grid.
Sat, Jan 21 2006 09:17:21    Mail sent by guest  
This problem goes away if the location is defined using EPSG 2926 instead of
the old text-based interface to state plane (see my original post)

# NAD83(HARN) / Washington North (ftUS)
<2926> +proj=lcc +lat_1=48.73333333333333 +lat_2=47.5 +lat_0=47
+lon_0=-120.8333333333333 +x_0=500000.0001016001 +y_0=0 +ellps=GRS80
+to_meter=0.3048006096012192 +no_defs  <>

This makes me wonder whether the old text-based projection definition dialogs
should be changed to work with proj.4 directly istead of maintaining a bunch
of different projection definitions.

David
Sat, Jan 21 2006 15:43:30    Mail sent by msieczka  
David wrote:

> This problem goes away if the location is defined using EPSG 2926 instead of
> the old text-based interface to state plane (see my original post)

David,

I set up a location from EPSG 2926 just being curious. I can see it is pretty
much different than the one you set up manualy in you original example. Now it's:
GRASS 6.1.cvs (std):~ > g.proj -p
-PROJ_INFO-------------------------------------------------
name       : Lambert Conformal Conic
proj       : lcc
a          : 6378137
es         : 0.006694380022900787
lat_1      : 48.73333333333333
lat_2      : 47.5
lat_0      : 47
lon_0      : -120.8333333333333
x_0        : 500000.0001016001
y_0        : 0
no_defs    : defined
-PROJ_UNITS------------------------------------------------
unit       : US survey foot
units      : US survey foots
meters     : 0.3048006096012192

Differences from you original example:
1. no datum
2. no nadgrids
3. lon_0 has no w suffix
4. lat_0-2 has no n suffix
5. unit and units names are different in both cases
6. ellps shape and x,y shifting are expressed in plain numbers instead of
exponents

Try playing with those differences until you find the reason for d.grid not
working. My first shot would be at unit names, datum next and the others last.
Please Cc grass5@grass.itc.it when you reply from the bugtracker - it won't
done automatically.

Maciek
Sat, Jan 21 2006 19:58:59    Mail sent by guest  
I think I found the problem. The presence of nadgrids prevents d.grid -g from
working. If you remove the nadgrids or create a state plane projection that
does not include the nadgrids then it works.

nadgrids are an empirical projection that is not mathematically defined (the
grids are used to look up the coordinate transformation values). That may be
the root of the problem.

There are also some problems with g.proj and nadgrids which I will file as a
seperate bug.

David
Sat, Jan 21 2006 20:31:18    Mail sent by guest  
OK, I understand exactly what is happening now. The bug is in the user not grass.
The HARN grids only cover Washington and Oregon. The part of the map I am
drawing includes some of Canada. That is outside the transformation grid and
therefore it cannot be projected. Hence the failure:

GRASS 6.1.cvs (WASPN_NAD83):~ > d.grid size=00:30:00 origin=0,0 
color=170:170:170 bordercolor=0:0:0 -g
pj_transform() failed
cause: failed to load NAD27-83 correction file
ERROR: Error in pj_do_proj

The reason it worked in the one instance I mentioned above is because I failed
to assign a transformation grid. In that case there are no problems drawing
Canada and Washington together since I am just using a simple mathematical
projection.

The error message in this case could be a bit more clear. Something like:

pj_transform() failed
cause: current region extends beyond the HPGN transformation grid boundary. 
David
Sat, Jan 21 2006 20:47:56    Mail sent by guest  
Good you sorted it out.

I'm changing the subject and make it a wish.

Maciek
Sat, Jan 21 2006 20:51:57    Subject changed to d.grid, pj_transform() failed: be more informative when error due to outside the transformation grid by msieczka  
Sat, Jan 21 2006 20:52:38    Area changed to wish6 by msieczka  
Sun, Jan 22 2006 02:22:17    Mail sent by hamish_nospam@yahoo.com  
Return-Path <hamish_nospam@yahoo.com>
Delivered-To grass-bugs@lists.intevation.de
Date Sun, 22 Jan 2006 14:22:00 +1300
From Hamish <hamish_nospam@yahoo.com>
To Request Tracker <grass-bugs@intevation.de>
Cc grass5@grass.itc.it
Subject Re: [GRASS5] [bug #4028] (grass) d.grid -g fails for Washington State Plane South Projection
Message-Id <20060122142200.40c013a8.hamish_nospam@yahoo.com>
In-Reply-To <20060121075345.06C921005A8@lists.intevation.de>
References <20060121075345.06C921005A8@lists.intevation.de>
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> this bug's URL: http://intevation.de/rt/webrt?serial_num=4028
> ---------------------------------------------------------------------
> 
> Subject: d.grid -g fails for Washington State Plane South Projection
..
> Problem: d.grid -g fails to draw a geographic grid in the Washington
> State Plane South projection:
..
> nadgrids   : WO
..
> d.grid -g size=1 color=red origin=0,0 bordercolor=blue
> pj_transform() failed
> cause: failed to load NAD27-83 correction file
> ERROR: Error in pj_do_proj

Note that it will fail if you extend the region beyond the edge of the
grid file. I am not sure where the "WO" grid covers, but try zooming
to an inland county within that region or switching to a 3 or 7 param
datum shift & see if you still get the same problem.


Hamish


Fri, Jan 27 2006 16:21:16    Mail sent by guest  
It should be a wish for PROJ.4, not for GRASS. The same error message is 
reported for many separate errors relating to the gridshift datum 
transformations. I know it has been mentioned on the PROJ mailing list 
before, but in a quick search I could find no related wish in the PROJ 
bugzilla. I may have missed it though.
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