specific development discussions on the Cartographic Projections Library (PROJ.4)

Antonio M. Guirado | 10 Jan 2003 15:31

FROM ELLIPSOID WGS84 TO UTM DT50

Hi,

I'd like to know how to convert values in WGS84 (latitude, longitude) that are obtained from a GPS to (X,Y)
UTM datum European 1950 (Spain Zone=30).

I have just to install "proj" and I don't know how I can do it.

Can anyone help me?

If proj is not able to do it (I think so). Could anybody tell me the way to do it?. I think helmert method is
possible but 
I can't find the value of the parameters and the formules.

Thanks in advance.
Regards

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William Hersman | 30 Jan 2003 00:06

Pseudo X/Y values, forward and reverse

We are struggling with the following problem.  Perhaps someone could
comment.

Alaska has 10 Stateplane zones.  Let's say a point exists in zone 10 and we
want the pseudo x/y for zone 4.  On forward projection the given lat/long
returns x/y values calculated for zone 4. When one then re-inputs the x/y
values into the algorithm to get a lat/long, the inverse does not return to
the same point.  In fact, in terms of feet, it is nearly a mile off !  What
might be going wrong here, and should one expect to be able to "round-trip"
a point when junmping across zones?

Thanks,

Willy Hersman
ConocoPhillips, Alaska

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Ed McNierney | 30 Jan 2003 01:13

RE: Pseudo X/Y values, forward and reverse

Willy -

Can you provide us with the numbers you're using in your sample?

Are you correctly interpreting and re-entering the lat/lon values?  It
sounds like you could be getting (for example) output lat/lon in degrees
and decimal minutes which is being input as degrees/minutes/seconds.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: (978) 251-4242   Fax: (978) 251-1396
ed <at> topozone.com

-----Original Message-----
From: William Hersman [mailto:Willy.Hersman <at> conocophillips.com] 
Sent: Wednesday, January 29, 2003 6:07 PM
To: osrs-proj <at> remotesensing.org
Subject: [OSRS-PROJ] Pseudo X/Y values, forward and reverse

We are struggling with the following problem.  Perhaps someone could
comment.

Alaska has 10 Stateplane zones.  Let's say a point exists in zone 10 and
we
want the pseudo x/y for zone 4.  On forward projection the given

(Continue reading)

William Hersman | 30 Jan 2003 02:19

RE: Pseudo X/Y values, forward and reverse


Input    -175.1234589    59.7654305  DD
Return   -4054878.4814   2990301.082 ASP 4 FEET
Input    -4054878.4814   2990301.082 ASP 4 FEET
Return   -175.1487387    59.7638269  DD

                                                                                                          
                    "Ed McNierney" <ed <at> topozone.com>                                                      
                    Sent by: owner-osrs-proj <at> remotesensing.org                                            

                                                                                                          
                    01/29/2003 03:13 PM                                                                   
                    Any replies will be addressed to: osrs-proj                                           

                     To:   <osrs-proj <at> remotesensing.org>                                                  
                     cc:                                                                                  
                     Subject:    RE: [OSRS-PROJ] Pseudo X/Y values, forward and reverse                   

Willy -

Can you provide us with the numbers you're using in your sample?

Are you correctly interpreting and re-entering the lat/lon values?  It
sounds like you could be getting (for example) output lat/lon in degrees
and decimal minutes which is being input as degrees/minutes/seconds.

           - Ed

Ed McNierney
President and Chief Mapmaker

(Continue reading)

Clifford J Mugnier | 30 Jan 2003 04:15

RE: Pseudo X/Y values, forward and reverse


Zone 10 is Lambert Conformal Conic (Aleutian Islands) and should return to
the same starting coordinates when going great distances from the central
meridian of zone 10.  Such is NOT the case for Transverse Mercator which is
zones 2-9.

Cliff Mugnier
LOUISIANA STATE UNIVERSITY
------------------------------------
Input    -175.1234589    59.7654305  DD
Return   -4054878.4814   2990301.082 ASP 4 FEET
Input    -4054878.4814   2990301.082 ASP 4 FEET
Return   -175.1487387    59.7638269  DD

"Ed McNierney" <ed <at> topozone.com>
Sent by: owner-osrs-proj <at> remotesensing.org

01/29/2003 03:13 PM
Any replies will be addressed to: osrs-proj

To:   <osrs-proj <at> remotesensing.org>
cc:
Subject:    RE: [OSRS-PROJ] Pseudo X/Y values, forward and reverse

Willy -

Can you provide us with the numbers you're using in your sample?

Are you correctly interpreting and re-entering the lat/lon values?  It
sounds like you could be getting (for example) output lat/lon in degrees

(Continue reading)

Frank Warmerdam | 30 Jan 2003 23:02

Picon

Re: Pseudo X/Y values, forward and reverse

William Hersman wrote:
> Input    -175.1234589    59.7654305  DD
> Return   -4054878.4814   2990301.082 ASP 4 FEET
> Input    -4054878.4814   2990301.082 ASP 4 FEET
> Return   -175.1487387    59.7638269  DD

William,

It would clearly help alot if you could provide the details of the
coordinate system.  I tried this:

warmerda <at> gdal2200[237]% proj -I -v +init=nad27:5004 +units=ft
#Transverse Mercator
#       Cyl, Sph&Ell
# +init=nad27:5004 +units=ft +proj=tmerc +datum=NAD27 +lon_0=-150 +lat_0=54
# +k=.9999 +x_0=152400.3048006096 +y_0=0 +no_defs +ellps=clrk66
# +nadgrids=conus,ntv1_can.dat
-4054905.40     2990291.47             (input)
175d7'10.261"W  59d45'56.295"N         (output)

warmerda <at> gdal2200[238]% proj -v +init=nad27:5004 +units=ft
#Transverse Mercator
#       Cyl, Sph&Ell
# +init=nad27:5004 +units=ft +proj=tmerc +datum=NAD27 +lon_0=-150 +lat_0=54
# +k=.9999 +x_0=152400.3048006096 +y_0=0 +no_defs +ellps=clrk66
# +nadgrids=conus,ntv1_can.dat
175d7'10.261"W  59d45'56.295"N          (input)
-4054186.84     2990083.90              (output)

I see there is an over 700 ft difference in the positions.  Far more than

(Continue reading)

Clifford J Mugnier | 30 Jan 2003 23:53

Re: Pseudo X/Y values, forward and reverse

Frank,

It's the implementation.  I think John P. Snyder's book and formulae were
used for PROJ4.  That would mean that the formulae for TM are to the 5th
derivative.  That barely gets to +/- 3 degrees from the central meridian.
7th derivative gets almost to 4 degrees difference.  Fifteenth derivative
gets to +/- 24 degrees from the central meridian with 1 mm "round-trip"
computational accuracy.

Cliff Mugnier
LOUISIANA STATE UNIVERSITY
William Hersman wrote:
> Input    -175.1234589    59.7654305  DD
> Return   -4054878.4814   2990301.082 ASP 4 FEET
> Input    -4054878.4814   2990301.082 ASP 4 FEET
> Return   -175.1487387    59.7638269  DD

William,

It would clearly help alot if you could provide the details of the
coordinate system.  I tried this:

warmerda <at> gdal2200[237]% proj -I -v +init=nad27:5004 +units=ft
#Transverse Mercator
#       Cyl, Sph&Ell
# +init=nad27:5004 +units=ft +proj=tmerc +datum=NAD27 +lon_0=-150 +lat_0=54
# +k=.9999 +x_0=152400.3048006096 +y_0=0 +no_defs +ellps=clrk66
# +nadgrids=conus,ntv1_can.dat
-4054905.40     2990291.47             (input)

(Continue reading)

William Hersman | 31 Jan 2003 00:58

Re: Pseudo X/Y values, forward and reverse


Cliff,

Thank you, this is making more sense now.  The number of derivatives used
in the algorithm limits how far from the central meridian that you can go
and still expect to return to the same lat/long.  Is this only on the
inverse calculation or is this on the forward calculation as well.  In
other words, do the calculated x/y values from the forward projection
suffer in accuracy?  Also, was there some reason why they did not carry out
the formula with more derivatives in PROJ4?

William Hersman
ConocoPhillips, Alaska

                                                                                                          
                    "Clifford J Mugnier" <cjmce <at> lsu.edu>                                                  
                    Sent by: owner-osrs-proj <at> remotesensing.org                                            

                                                                                                          
                    01/30/2003 01:53 PM                                                                   
                    Any replies will be addressed to: osrs-proj                                           

                     To:   osrs-proj <at> remotesensing.org                                                    
                     cc:                                                                                  
                     Subject:    Re: [OSRS-PROJ] Pseudo X/Y values, forward and reverse                   

Frank,

It's the implementation.  I think John P. Snyder's book and formulae were
used for PROJ4.  That would mean that the formulae for TM are to the 5th

(Continue reading)

Clifford J Mugnier | 31 Jan 2003 06:22

Re: Pseudo X/Y values, forward and reverse


William,

Yes, it counts in BOTH directions.  I'm currently writing the chapter on
"Object Space Coordinate Systems" for the new 5th edition of the "Manual of
Photogrammetry," and I'm including up to the 7th derivative in both direct
and inverse transformations.  Why weren't greater expansions included into
PROJ4?  It's not a topic of general interest in cartography.  Cartographers
generally ignore such things, including the late John P. Snyder.  John was
only interested in what was germain to the U.S. Geological Survey and the
scales of maps that they produced.  John was never interested in geodetic
stuff.  John avoided datums and such things.

WGS84 was a topic of vague interest at the time, NAD83 was just coming on
line, and cartographic interests were beginning to be getting into GIS
applications at the time.  Remember now, that was 20 years ago!  When it
came to private consulting stuff, John used my software (GRIDS 2.0)with the
full 15th derivative implementations in both direct and inverse for
transverse Mercator.  USGS stuff was nice, but when it came to "real world"
applications, well ...

What's one of the rarest books ever printed?  Try TM 5-241-10 "Universal
Transverse Mercator Grid EXTENSION OF ZONE TO ZONE TRANSFORMATION TABLES."
Sept, 1962, 642 pp.

No, I'm not going to fax a copy.  Yes, it has the only copy (ever) of the
equations to the 15th derivative.

Conoco in Ponca City, OK., purchased a copy of my 7th derivative equations
of the Gauss-Krueger Transverse Mercator transformation back in 1988-1989.

(Continue reading)

Gerald I. Evenden | 31 Jan 2003 21:15

Picon

Re: Pseudo X/Y values, forward and reverse

I am very sorry, but I consider the current thread nonsense.
Anyone carrying the TM projection ellipsoid projection beyond
3.5 degrees of the CM is up to no good.  UTM does not require
greater extension and the scale factor beyone 3.5 degrees
makes it useless as an accurate conformal projection.

Adding factors to the equations is merely a waste of computer
time.

'Nuff said.

On Fri, 2003-01-31 at 00:22, Clifford J Mugnier wrote:
> 
> William,
> 
> Yes, it counts in BOTH directions.  I'm currently writing the chapter on
> "Object Space Coordinate Systems" for the new 5th edition of the "Manual of
> Photogrammetry," and I'm including up to the 7th derivative in both direct
> and inverse transformations.  Why weren't greater expansions included into
> PROJ4?  It's not a topic of general interest in cartography.  Cartographers
> generally ignore such things, including the late John P. Snyder.  John was
> only interested in what was germain to the U.S. Geological Survey and the
> scales of maps that they produced.  John was never interested in geodetic
> stuff.  John avoided datums and such things.
	...

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