[GRASS-user] m.proj query

[Hermann Peifer]

On 2013-09-28 11:45, John Nicholls wrote:
> and with a smaller sized image attached
> also here is the format of the original .csv  file
>
> x,y,z1,z2
> 132073.04,161644.42,-43.00,71.43
> 132073.01,161644.37,-43.00,71.431
> 132072.97,161644.32,-42.90,71.432
> 132072.93,161644.28,-43.00,71.432
> 132072.90,161644.23,-43.20,71.433
> 132072.86,161644.18,-43.30,71.433
> 132072.83,161644.14,-43.40,71.434
> 132072.79,161644.10,-43.40,71.435
> 132072.76,161644.05,-43.60,71.435
> 132072.72,161644.00,-43.60,71.436
>
> Hi,
>
> I am using m.proj on a .csv file  containing magnetic and gps data
> (x,y,z1,z2) to convert coordinates from UTM Zone 31N (EPSG 32631) to
> Lambert 72 (Belgium), EPSG 31370.
>
> GRASS 6.4.3RC3 (2013) Ubuntu Release 12.04 (precise) 32-bit.
> The input data file contains X and Y coordinates in UTM Zone 31N, with
> columns z1 for magnetic readings, and z2 for elevation.
> Grass Location 13009 created using EPSG code 32631
>

You could re-project with ogr2ogr and see if this helps. Let's say your 
data file is "original.csv" with the columns as given above. Then you'd 
need a .vrt file like this one:

$ cat original.vrt
<OGRVRTDataSource>
     <OGRVRTLayer name="original">
         <SrcDataSource>original.csv</SrcDataSource>
         <GeometryType>wkbPoint</GeometryType>
         <LayerSRS>EPSG:32631</LayerSRS>
         <GeometryField encoding="PointFromColumns" x="x" y="y"/>
     </OGRVRTLayer>
</OGRVRTDataSource>

... and use ogr2ogr like this:

$ ogr2ogr reprojected.shp original.vrt -t_srs EPSG:31370

My debug output tells me that this transformation has been carried out 
(which looks pretty much like what you mentioned).

OGRCT: Source: +proj=utm +zone=31 +datum=WGS84 +units=m +no_defs

OGRCT: Target: +proj=lcc +lat_1=51.16666723333333 +lat_2=49.8333339 
+lat_0=90 +lon_0=4.367486666666666 +x_0=150000.013 +y_0=5400088.438 
+ellps=intl 
+towgs84=-106.869,52.2978,-103.724,0.3366,-0.457,1.8422,-1.2747 +units=m 
+no_defs