[GRASS-user] custom projection

GRASS GRASS user
,
1

Hi,
I am working on a mineral potential mapping project using satellite,
ground geological, geophysical, geochemical data in the Mahabubnagar,
Nalgonda districts of Andhra Pradesh. I am using grass as a module in
the QGIS. When I checked the projections availble, I could not find
the modified everest datum of 1956. Instead one 1962 definition is
close to it with very minute difference from the parameters given in
the commercial software like ERDAS Imagine. And also I could not
figure out the setting of coordinates to latitude and longitude.
Kindly help me in this regard

ramarajua

2

ramaraju wrote on 09/06/2007 10:47 AM:

Hi,
I am working on a mineral potential mapping project using satellite,
ground geological, geophysical, geochemical data in the Mahabubnagar,
Nalgonda districts of Andhra Pradesh. I am using grass as a module in
the QGIS. When I checked the projections availble, I could not find
the modified everest datum of 1956.

GRASS uses the PROJ4 software which supports Everest 1956:

cs2cs -le | grep -i everest
  evrst30 a=6377276.345 rf=300.8017 Everest 1830
  evrst48 a=6377304.063 rf=300.8017 Everest 1948
  evrst56 a=6377301.243 rf=300.8017 Everest 1956
  evrst69 a=6377295.664 rf=300.8017 Everest 1969
  evrstSS a=6377298.556 rf=300.8017 Everest (Sabah & Sarawak)

The definition is also present in GRASS:

GRASS 6.3.cvs (nc_spm_06):~ > grep -i ever $GISBASE/etc/ellipse.table
# Everest 1830, India
# everest a=6377276.345
e=.0066378466
everest "Everest 1830, India" a=6377276.345 f=1/300.8017
evrst30 "Everest 1830, India" a=6377276.345 f=1/300.8017
# Everest 1948, W. Malaysia and Singapore
evrst48 "Everest 1948" a=6377304.063 f=1/300.8017
# Everest 1956, India
evrst56 "Everest 1956, India" a=6377301.243 f=1/300.8017
# Everest 1969, W. Malaysia
evrst69 "Everest 1969, W. Malaysia" a=6377295.664 f=1/300.8017
# Everest (Sabah & Sarawak), Brunei and E. Malaysia
evrstss "Everest Sabah and Sarawak" a=6377298.556 f=1/300.8017
# Modified Everest (from elist.html from Peter H. Dana, cited from DMA 1987
# everest_m "Modified Everest" a=6377304.063
b=6356103.039
everest_m "Modified Everest" a=6377304.063 f=1/300.8017
# Everest (Pakistan)
everest_p "Everest (Pakistan)" a=6377309.613 f=1/300.8017

When selecting the ellipsoid, use 'list' to get the list or enter
directly 'evrst56'.

And also I could not
figure out the setting of coordinates to latitude and longitude.
Kindly help me in this regard
  

Please take a look at the available documentation:
http://grass.itc.it/gdp/tutorials.php
http://grass.itc.it/gdp/books.php

Markus

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ITC -> dall'1 marzo 2007 Fondazione Bruno Kessler
ITC -> since 1 March 2007 Fondazione Bruno Kessler
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