From: kang@risca.rs.msu.edu
Date: Tue, 25 Oct 1994 16:30:01 -0400
Sender: grass-lists-owner@moon.cecer.army.mil
To: grassu-list@max.cecer.army.mil
Subject: Re: World Projection PeaceDoes GRASS include the Helmert 1906 spheroid? If not, is there a projection
package allow me to transfer a set of xy coordinates from Transverse Mercator
with Helmert 1906 spheroid to UTM with interanational 1909 spheroid?Yung-Tsung Kang
Center for Remote Sensing, Michigan State University
In *proj* parlance, inverting with "+ellps=helmert" and forwarding with
"+ellps=intl" would do the trick. If the ellipsoids cannot be referenced
by name, their values are:
Helmert 1906: a=a=6378200. rf=298.3 ("rf" is 1/f or reciprocal of flattening.)
International 1909: a=6378388.0 rf=297.
You will need to know the other projection factors associated with the
Transverse Mercator projection such as central meridian, scale factor
at central meridian, false eastings/northings, etc.
As far as GRASS versions of proj (?.proj) I do not know the details of
execution, but if these fail, you can definitely do the job with
*proj* from the PROJ.4 package on charon.er.usgs.gov (128.128.40.24).
Gerald (Jerry) I. Evenden Internet: gie@charon.er.usgs.gov
voice: (508)563-6766 Postal: P.O. Box 1027
fax: (508)457-2310 N.Falmouth, MA 02556-1027