[Proj] Re: Proj Digest, Vol 51, Issue 2

Gerald I. Evenden geraldi.evenden at gmail.com
Mon Aug 11 10:36:52 EDT 2008

On Monday 11 August 2008 4:07:58 am Neil Robinson wrote:
> Hi Gerard,
> Thanks for your response. I realise that this isn't a support forum, but
> I'm not getting any joy anywhere else and you are clearly very
> knowledgeable on this topic
> I tried lodging a bug with qgis [1], but they seemed to think the problem
> was with proj4 (although, through my ignorance that was my guess, so I
> might have planted the seed of that conclusion).
> > I would just use +proj=tmerc and put some added '-' flags to juggle the
> > I/O.
> > But that's somebody else's job as I only work on the library.  ;-)
> I tried this suggestion (I think I did), but negative zero doesn't make any
> sense to proj4.
> Without adding the '-' flags, this is what I think the parameters need to
> be for one of the projections I'm interested in:
> +proj=tmerc +ellps=WGS84 +lat_0 +lon_29 +k=1 +towgs84=0,0,0,0,0,0,0
> +units=m +no_defs

Can you give a sample input (lat/lon) and an approximation of what you expect 
(without datum conversion which I cannot handle).  Under normal circumstances 
the above would generate (viewed as a console screen capture):

gie at charon:~$ lproj +proj=tmerc +ellps=WGS84 +lon_0=29
31 45
157693.72       4986890.93

Note; option +towgs84 and +no_defs is not on my software and the other options 
are defaulted as you explicitly specified.

The input is longitude(31), latitude(45) and the output is easting(x) and 
northing(y) in meters.

What output would you prefer to see?

The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist

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