[Proj] Altering the +south paramter using UTM

[Frank Warmerdam]

On 12/21/05, Chris Tweedie <chris at narx.net> wrote:
> Hopefully this is a quick question but I am in the process of trying to
> formulate the right parameters to transform data held in a modified UTM Zone
> 50 projection (epsg 28350) to GDA94 (epsg4283)
>
> The only modification is to the false northing, so instead of 10,000,000
> which I assume is the default value for +south, this data is stored with
> 16,000,000. I have been trying the following but no matter what I try I
> don't seem to be able to modify the default value using +south= or +y_0=. Is
> there a dependency to specify any other parameters with it?
>
> cs2cs +proj=utm +zone=50 +y_0=16000000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0
> +units=m +to +proj=longlat +ellps=GRS80

Chris,

It isn't utm anymore if you change the false northing.  Just
do it as transverse mercator.

+proj=tmerc +lat_0=0 +lon_0=117 +k=0.9996 +x_0=500000 +y_0=1600000
       +ellps=GRS80 +towgs84=0,0,0

Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent