[GRASS-user] m.proj query

[John Nicholls]

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

v.info report following v.in.ascii
 +----------------------------------------------------------------------------+
  Layer:           kes1with105melevation at user1                           
  Mapset:          user1                                                 
  Location:        13009                                                 
  Database:        /home/john/grassdata                                  
  Title:                                                                 
  Map scale:       1:1                                                   
  Map format:      native                                                
  Name of creator: john                                                  
  Organization:                                                          
  Source date:     Wed Sep 18 20:56:03 2013                              
 ----------------------------------------------------------------------------
    Type of Map:  vector (level: 2)                                      
                                                                             
    Number of points:       180396          Number of areas:      0      
    Number of lines:        0               Number of islands:    0      
    Number of boundaries:   0               Number of faces:      0      
    Number of centroids:    0               Number of kernels:    0      
                                                                             
    Map is 3D:              Yes                                          
    Number of dblinks:      1                                            
                                                                             
          Projection: Universal Transverse Mercator (zone 0)             
                N:        5624356.51    S:        5624234.54             
                E:         578607.33    W:         578473.65             
                B:            -100.9    T:              96.8

m.proj in location 13009
m.proj input=/media/VAIO/DATA/kes1with105melevation_out.csv
output=kes1with105melevation_out_projected fs=, proj_in=+proj=utm
+zone=31 +datum=WGS84 +units=m +no_defs proj_out=+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

Switching to my Belgium Lambert 72 Location created using EPSG code
31370
v.in.ascii -z --overwrite
input=/home/john/kes1with105melevation_out_projected
output=kes1with105melevation_out_projected fs=, skip=1 columns=x double,
y double, z1 double, z2 double z=3

when displaying the new vector on top of the background map and survey
perimeter the vector is c.100m to the south-east of where it should be
(see attached screengrab).

I have checked the proj.4 parameters in usr/share/proj/epsg, and these
appear to be correct:
32631 = +proj=utm +zone=31 +datum=WGS84 +units=m +no_defs
31370 = +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

There have been past exchanges relating to errors in the proj.4
parameters for Belgium Lambert 72 31370, but here they seem to be
correct. It's probable I am making an error somewhere, either missing an
intermediate process or getting some of the parameters incorrect along
the way.

Can anyone help? 

Cheers,

John

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