[Proj] request help with Transverse_Mercator in proj SOLVED

Rick Graves gravesricharde at yahoo.com
Mon Aug 13 14:46:33 PDT 2012



Mikael,

> I think you have just switched the values of x_0 and y_0, since x_0 should be False_Easting and y_0 should be False_Northing.

How could I make such a mistake!

I appreciate your help.

Also, I will go with +k_0.

Thanks,

Rick


________________________________
 From: Mikael Rittri <Mikael.Rittri at carmenta.com>
To: Rick Graves <gravesricharde at yahoo.com>; PROJ.4 and general Projections Discussions <proj at lists.maptools.org> 
Sent: Monday, August 13, 2012 10:29 PM
Subject: RE: [Proj] request help with Transverse_Mercator in proj
 

 
Hello Rick,
I think you have just switched
the values of x_0 and y_0, since x_0 should be False_Easting and y_0 should be
False_Northing.
 
With Proj 4.8.0, I get
 
C:\Windows\System32>proj
+proj=tmerc +lat_0=0 +lon_0=-90 +k=0.9996 +y_0=-4480000.0 +x_0=520000.0 -v
 
#Transverse
Mercator
#      
Cyl, Sph&Ell
#
+proj=tmerc +lat_0=0 +lon_0=-90 +k=0.9996 +y_0=-4480000.0 +x_0=520000.0
#
+ellps=WGS84
 
-92.88943290699996
45.64120292600006
 
294824.82      
578245.14
 
which is at least near
your expected result. (Maybe I made some other mistake.) 
 
I would prefer to give
the +ellps explicitly, but the default seems to be what you need, or nearly so. 
(Not much difference
between the WGS84 and the GRS_1980 ellipsoid.) 
 
And I think +k_0 is now
the recommended parameter name instead of +k, but it seems that +k still works.
 
Best regards,
 
Mikael Rittri
Carmenta
Sweden
http://www.carmenta.com
 

________________________________
 
From:proj-bounces at lists.maptools.org [mailto:proj-bounces at lists.maptools.org] On Behalf Of Rick Graves
Sent: Monday, August 13, 2012 3:42
AM
To: PROJ.4 Projections Discussions
Subject: [Proj] request help with
Transverse_Mercator in proj
 
Hey,
 
Sorry
to trouble you, but I still have a couple of states for which I need to get
proj.4 working.  This time, it is Wisconsin.
 
I am
starting with the Western most point in the state.  If you plug the
following into maps.google.com, you will see it:
 
45.64120292600006,
-92.88943290699996 
 
I
downloaded the shapefiles from the state web site.  In the shapefile, the
minimum X point is this:
 
294822.7664999999,
578184.1052999999
 
Here is
the metadata from the prj file:
 
PROJCS["NAD_1983_HARN_Wisconsin_TM",
GEOGCS["GCS_North_American_1983_HARN",
DATUM["D_North_American_1983_HARN",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",520000.0],
PARAMETER["False_Northing",-4480000.0],
PARAMETER["Central_Meridian",-90.0],
PARAMETER["Scale_Factor",0.9996],
PARAMETER["Latitude_Of_Origin",0.0],
UNIT["Meter",1.0]]
 
I
initialized proj as follows:
 
proj
+proj=tmerc +lat_0=0.0 +lon_0=-90.0 +k=0.9996 +x_0=-4480000.0 +y_0=520000.0
 
When
give proj this: 
 
-92.88943290699996
45.64120292600006
 
I get
this:
 
-4705175.18
    5578245.14
 
But I
am expecting this:
 
294822.7664999999,
578184.1052999999
 
I
assume I am not initializing proj correctly.  
 
If
someone could spot my mistake, I would appreciate it.
 
Thanks,
 
Rick
Graves
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