How does the Molodesky transformation work? Has anyone an Excel spreetsheet
for this transformation? Where can I get info?
Thanks in advance, ROLF
http://www.auslig.gov.au/geodesy/calcs.htm has some good information and
excel spreadsheets for both datum conversions (Molodensky) and
conversions from Lat/Long to grids (Redfearn's formulae).
These may help you but the emphasis is on Australian grids and datums so
they will require a little work in your case.
Also Peter Dana's Geographers Craft web pages have some information
which may help. The Molodensky transformation is at
http://www.utexas.edu/depts/grg/gcraft/notes/datum/gif/molodens.gif
--
Dominic Sexton
http://www.dscs.demon.co.uk/
Try on Garmin Receivers:
User Datum: DX: 24m
DY: -123m
DZ: -94m
DA: -108.0m
DF: 0.0048079
User Grid: LONGITUDE ORIGIN: E015 00.000
SCALE: 1.0000000
FALSE EASTING: 5000000.0m
FALSE NORTHING: 0.0m
If you don't have a Garmin or other GPS receiver capable of
User Datum and User Grid definition:
The UTM grid is a one kilometer grid with an orientation to true
north called "Grid North" and has easting and northing values
marked on the edges of printed maps.
The gauss-krueger coordinate system also has a one kilometer grid
with an orientation to true north called "Grid North" and has easting
and northing values marked on the edges of printed maps. A transformation
of the two grids should consist of translation and rotation matrices, with
constants being a function of location.
I have two sets of Berlin topographic maps. 1:25,000 and 1:10,000 dated
1986. The one-kilometer grid is not UTM. I found the angular orientation
of the grid with respect to true north to be almost identical to that of t
he UTM one-kilometer grid for this region.
Applying a linear transform of 47 meters easting and -2430 meters northing
I can convert back and forth between UTM and the grid used on these
Berlin maps. The transform values vary about 5 meters from opposite sides
of area covered in the Berlin map sets.
Using an HP-48SX and placing the easting and northing values on the stack:
UTM->GK
<< ->V2 [47 -2430] - V-> >>
GK->UTM
<< ->V2 [47 -2430] + V-> >>
___________________________________________________
Sam Wormley - http://www.cnde.iastate.edu/maps.html
Check the following references (in German):
Kleinefeld, H.-J. 1991. Datumstransformation vom WGS 84 in das
Gauß-Krüger-Koordinatensystem. Verm.-Ing. 5/1991. pp 200-202.
Schödlbauer, A. 1981. Rechenformeln und Rechenbeispiele zur Landesvermessung
Teil 1. Herbert Wichmann Verlag. Karlsruhe.
Schödlbauer, A. 1982. Rechenformeln und Rechenbeispiele zur Landesvermessung
Teil 2. Herbert Wichmann Verlag. Karlsruhe.
Got an old Excel-sheet somewhere which do the transformation, email me
directly if you need if very urgent.
Gruesse
holger