Coordinate transformation returning NaN

[stretch]

Hi all

I am following on from a post i made a couple of weeks ago (here:http://n2.nabble.com/map-coordinates-in-different-coordinate-system-td3224904.html). It was suggested to post here.

Firstly. I am trying to reproject from 4148 to 2054 (hartebeesthoek94 Lo31). Much discussion in my previous post, and indeed on other mailing lists (i.e GDAL) relates to this projection and the fact that it is south orientated. Let me firstly try and clarify as we have had some discussion around this very topic on the africa osgeo mailing list.
1. Officially (i think) hartebeesthoek94 used a modified South Orientated transverse mercator projection
2. Only some surveyors and engineers use this in Cad packages
3. 99% of all GIS users in South Africa do NOT use this South orientated Transverse Mercator and instead use  the standard transverse mercator (with Hartebeesthoek/WGS84 datum and WGS84 ellipsoid)

What I am trying to accomplish should therefore NOT rely on support for a south orientated projection.

Here is my code:

    Proj4js.defs["EPSG:2054"] = "+proj=tmerc +ellips=WGS84 +datum=WGS84 +lon_0=31 +units=m +no_defs";
    Proj4js.defs["EPSG:4148"]  = "+proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs ";
   
    var source = new Proj4js.Proj('EPSG:4148');    //source coordinates will be in Longitude/Latitude
    var dest = new Proj4js.Proj('EPSG:2054');     //destination coordinates
 
    // transforming point coordinates
    var p = new Proj4js.Point(30.352,-29.623);   //any object will do as long as it has 'x' and 'y' properties
    Proj4js.transform(source, dest, p);      //do the transformation.  x and y are modified in place
    alert(p.x);
    alert(p.y);

the alert return "NAN", if i use EPSG:27563 as per the example, the alert return a correct value

On a further note if i run
cs2cs +proj=latlong +datum=WGS84 +to +proj=tmerc +lon_0=31 +datum=WGS84
and then enter:
30.352 -29.623
You will get:
-62758.77       -3278498.65 0.00

Which is the correct result:

I would appreciate any assistance in getting my transformation to work correctly
Regards
Andrew

[Mike Adair]

Hi Andrew,

You need to include the x_0, y_0 and lat_0 values for the EPSG:2054 def
string.  We should probably default those to 0 so you don't get this
error but the following def string will do as a workaround:

Proj4js.defs["EPSG:2054"] = "+proj=tmerc +ellips=WGS84 +datum=WGS84
+lon_0=31 +lat_0=0 +x_0=0 +y_0=0 +units=m +no_defs";

Mike

stretch wrote:

> Hi all
>
> I am following on from a post i made a couple of weeks ago
> (here:http://n2.nabble.com/map-coordinates-in-different-coordinate-system-td3224904.html).
> It was suggested to post here.
>
> Firstly. I am trying to reproject from 4148 to 2054 (hartebeesthoek94 Lo31).
> Much discussion in my previous post, and indeed on other mailing lists (i.e
> GDAL) relates to this projection and the fact that it is south orientated.
> Let me firstly try and clarify as we have had some discussion around this
> very topic on the africa osgeo mailing list.
> 1. Officially (i think) hartebeesthoek94 used a modified South Orientated
> transverse mercator projection
> 2. Only some surveyors and engineers use this in Cad packages
> 3. 99% of all GIS users in South Africa do NOT use this South orientated
> Transverse Mercator and instead use  the standard transverse mercator (with
> Hartebeesthoek/WGS84 datum and WGS84 ellipsoid)
>
> What I am trying to accomplish should therefore NOT rely on support for a
> south orientated projection.
>
> Here is my code:
>
>     Proj4js.defs["EPSG:2054"] = "+proj=tmerc +ellips=WGS84 +datum=WGS84
> +lon_0=31 +units=m +no_defs";
>     Proj4js.defs["EPSG:4148"]  = "+proj=longlat +ellps=WGS84
> +towgs84=0,0,0,0,0,0,0 +no_defs ";
>    
>     var source = new Proj4js.Proj('EPSG:4148');    //source coordinates will
> be in Longitude/Latitude
>     var dest = new Proj4js.Proj('EPSG:2054');     //destination coordinates
>  
>     // transforming point coordinates
>     var p = new Proj4js.Point(30.352,-29.623);   //any object will do as
> long as it has 'x' and 'y' properties
>     Proj4js.transform(source, dest, p);      //do the transformation.  x and
> y are modified in place
>     alert(p.x);
>     alert(p.y);
>
> the alert return "NAN", if i use EPSG:27563 as per the example, the alert
> return a correct value
>
> On a further note if i run
> cs2cs +proj=latlong +datum=WGS84 +to +proj=tmerc +lon_0=31 +datum=WGS84
> and then enter:
> 30.352 -29.623
> You will get:
> -62758.77       -3278498.65 0.00
>
> Which is the correct result:
>
> I would appreciate any assistance in getting my transformation to work
> correctly
> Regards
> Andrew
>  

--
   Michael Adair
   Senior Software Architect
   DM Solutions Group Inc.

   Office: [phone] x26
   [hidden email]
   http://www.dmsolutions.ca
   http://research.dmsolutions.ca


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[stretch]

Mike

A million thank you's - that worked perfectly!

Andrew

-----Original Message-----
From: Mike Adair [mailto:[hidden email]]
Sent: 23 July 2009 09:01 PM
To: stretch
Cc: [hidden email]
Subject: Re: [MetaCRS] Coordinate transformation returning NaN

Hi Andrew,

You need to include the x_0, y_0 and lat_0 values for the EPSG:2054 def
string.  We should probably default those to 0 so you don't get this
error but the following def string will do as a workaround:

Proj4js.defs["EPSG:2054"] = "+proj=tmerc +ellips=WGS84 +datum=WGS84
+lon_0=31 +lat_0=0 +x_0=0 +y_0=0 +units=m +no_defs";

Mike

stretch wrote:
> Hi all
>
> I am following on from a post i made a couple of weeks ago
>
(here:http://n2.nabble.com/map-coordinates-in-different-coordinate-system-td
3224904.html).
> It was suggested to post here.
>
> Firstly. I am trying to reproject from 4148 to 2054 (hartebeesthoek94
Lo31).
> Much discussion in my previous post, and indeed on other mailing lists
(i.e
> GDAL) relates to this projection and the fact that it is south orientated.
> Let me firstly try and clarify as we have had some discussion around this
> very topic on the africa osgeo mailing list.
> 1. Officially (i think) hartebeesthoek94 used a modified South Orientated
> transverse mercator projection
> 2. Only some surveyors and engineers use this in Cad packages
> 3. 99% of all GIS users in South Africa do NOT use this South orientated
> Transverse Mercator and instead use  the standard transverse mercator
(with

> Hartebeesthoek/WGS84 datum and WGS84 ellipsoid)
>
> What I am trying to accomplish should therefore NOT rely on support for a
> south orientated projection.
>
> Here is my code:
>
>     Proj4js.defs["EPSG:2054"] = "+proj=tmerc +ellips=WGS84 +datum=WGS84
> +lon_0=31 +units=m +no_defs";
>     Proj4js.defs["EPSG:4148"]  = "+proj=longlat +ellps=WGS84
> +towgs84=0,0,0,0,0,0,0 +no_defs ";
>    
>     var source = new Proj4js.Proj('EPSG:4148');    //source coordinates

will
> be in Longitude/Latitude
>     var dest = new Proj4js.Proj('EPSG:2054');     //destination
coordinates
>  
>     // transforming point coordinates
>     var p = new Proj4js.Point(30.352,-29.623);   //any object will do as
> long as it has 'x' and 'y' properties
>     Proj4js.transform(source, dest, p);      //do the transformation.  x
and

> y are modified in place
>     alert(p.x);
>     alert(p.y);
>
> the alert return "NAN", if i use EPSG:27563 as per the example, the alert
> return a correct value
>
> On a further note if i run
> cs2cs +proj=latlong +datum=WGS84 +to +proj=tmerc +lon_0=31 +datum=WGS84
> and then enter:
> 30.352 -29.623
> You will get:
> -62758.77       -3278498.65 0.00
>
> Which is the correct result:
>
> I would appreciate any assistance in getting my transformation to work
> correctly
> Regards
> Andrew
>  

--
   Michael Adair
   Senior Software Architect
   DM Solutions Group Inc.

   Office: [phone] x26
   [hidden email]
   http://www.dmsolutions.ca
   http://research.dmsolutions.ca


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