[MetaCRS] Proj4js: Converting from EPSG:4326 -> EPSG:28193 fails

Christopher Schmidt crschmidt at metacarta.com
Tue Mar 24 12:54:34 EDT 2009


On Tue, Mar 24, 2009 at 12:44:57PM -0400, Josh Rosenthal wrote:
> Hi Mike,
> Thanks a lot.  I couldn't figure out if I was doing something wrong or...
>  In any case, you said 'yet'.  Is there a timeline as to when we could
> expect cassini projections to be supported, or do you have any other
> suggestions as to how to convert coordinates to/from that?  Curiously, it
> appears as though spatialreference.org does support those reprojections,
> though I'm not sure what the back end is over there.

proj.4 itself, which is what proj4js is based on originally (but the
porting to js is incomplete).

-- Chris

> In any case, any advice would be welcome,
> 
> Thanks,
> 
> Josh
> 
> 2009/3/24 Mike Adair <madair at dmsolutions.ca>
> 
> > Josh,
> >
> > The cassini projection code ("proj=cass") hasn't been implemented in
> > Proj4js yet.
> >
> > Mike
> >
> >
> > Josh Rosenthal wrote:
> >
> >> Hi Folks,
> >>
> >> I hope I'm sending this to the right list.  Apologies if not.
> >>
> >> I'm hitting a bit of a problem with a proj4js conversion, and I'm hoping
> >> someone can help.  I'm trying to go from EPSG 4326 to 28193, and I'm just
> >> getting my original coordinates returned.  As per
> >> http://spatialreference.org/ref/epsg/28193/ , I have the proj4js
> >> definition for 28193 as:
> >> Proj4js.defs["EPSG:28193"] = "+proj=cass +lat_0=31.73409694444445
> >> +lon_0=35.21208055555556 +x_0=170251.555 +y_0=1126867.909 +a=6378300.789
> >> +b=6356566.435 +towgs84=-275.722,94.7824,340.894,-8.001,-4.42,-11.821,1
> >> +units=m +no_defs";
> >>
> >> To demonstrate, I've modified the converter in the proj4js homepage to
> >> also have 28193 (Old Israel Grid/Palestine 1923) and 2039 (New Israel Grid).
> >>  You can see the demo here: http://arkeotech.googlepages.com/Proj4js.htm
> >> Converting the coordinates 35,31 from 4326 to 2039 works fine, but from
> >> 4326 to 28193 just returns 35,31.  Looking at the spatial reference page for
> >> 28193, you can use the viewer to get an approximation for those
> >> coordinates... it should be somewhere roughly around 149353, 1046172
> >>
> >> Any thoughts?
> >>
> >> Thanks,
> >>
> >> Josh
> >>
> >>
> >>
> >> ------------------------------------------------------------------------
> >>
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> >>
> >>
> >
> > --
> >  Michael Adair
> >  Senior Software Architect
> >  DM Solutions Group Inc.
> >
> >  Office: (613) 565-5056 x26
> >  madair at dmsolutions.ca
> >  http://www.dmsolutions.ca
> >  http://research.dmsolutions.ca
> >
> >
> >

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-- 
Christopher Schmidt
MetaCarta


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