[Qgis-user] Custom Projection

[Andre Joost]

Am 11.09.2013 15:26, schrieb James David Smith:
> Hi there,
>
> I'm trying to make a custom project string so that I can view a NetCDF
> file in QGIS. I have data about the projection, but am struggling to
> make a PROJ string from it that QGIS requires. Could someone help me
> please? The fields that I can get from the file are as follows. I am
> also informed that it is Lambert Conformal Conic .
>
> P_ALP = 46. ; Double: First map projection descriptive parameter
> (dependent on projection type)
> P_BET = 46. ; Double: Second map projection descriptive parameter
> (dependent on projection type)
> P_GAM = 17. ; Double: Third map projection descriptive parameter
> (dependent on projection type)
> XCENT = 17. ; Double: Longitude for coordinate system center
> YCENT = 46. ; Double: Latitude for coordinate system center
> XORIG = -1219510. ; X-coordinate for lower-left (southwest) corner of
> the grid with respect to (XCENT,YCENT) (dependent on projection type)
> YORIG = 706490. ; Y-coordinate for lower-left (southwest) corner of
> the grid with respect to (XCENT,YCENT) (dependent on projection type)
> XCELL = 20. ; Double: X-coordinate grid cell size (dependent on projection type)
> YCELL = 20. ; Double: Y-coordinate grid cell size (dependent on projection type)
>
> Is this enough information to make the projection string?
>

After consulting this page:
http://niceguy.wustl.edu/mapserver/temp/HTML/GRIDS.html

it might be the follwoing projection:

+proj=lcc +lat_1=46.0 +lat_2=46.0 +lat_0=46.0 +lon_0=17.0 +ellps=GRS80 
+towgs84=0,0,0,0,0,0,0 +units=m +no_defs

The XORIG,YORIG,XCELL and YCELL are not used for the projection.

HTH,
André Joost