[Proj] Define custom proj4 CRS

Andre Joost andre+joost at nurfuerspam.de
Thu Jan 31 14:58:11 EST 2013

Am 31.01.2013 19:53, schrieb Hermann Peifer:
> Dear both,
> I just came to the same conclusion that EPSG:22523 would be the most
> appropriate CRS.

Me too, and it is in the standard database.

> However, as Stephane mentioned: the units of IBGE's DGN files are in km,
> so one has to define a custom CRS with these parameters (same as above
> with the exception of +units=km)
> +proj=utm +zone=23 +south +ellps=intl +towgs84=-206,172,-6,0,0,0,0 +units=km

I tried that, but QGIS does not like it:

In Bezugssystemeinheiten des Projekts : xMin,yMin 448.11;7345.03 : 
xMax,yMax 475.53;7374.02
Räumliches Bezugssystem des Layers:
+proj=utm +zone=23 +south +ellps=intl +towgs84=-206,172,-6,0,0,0,0 
+units=m +no_defs

having set this custom CRS:
+proj=utm +zone=23 +south +ellps=intl +towgs84=-206,172,-6,0,0,0,0 
+units=km +no_defs

Maybe the elliposid and towgs84 parametres must also be in kilometres then?

> On 2013-01-31 16:03, Jose Gonçalves wrote:

>> PS: The IBGE ftp site seems to be off.

No, not off, but very slow: 6 to 9 kb/sec. Took me 2 hours to download 

André Joost

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