[Proj] Hough Ellipse
Clifford J Mugnier
cjmce at lsu.edu
Sat May 10 14:51:03 EST 2014
We did not do any datum transformations when working with CORONA imagery. Everything was done in native formats, and positioning was essentially hung off of the orbital parameters and the occasional identifiable map points obtained from cartometric analysis. Any offsets you experience will essentially be in latitude, increasing in magnitude as you get closer to the poles. There will be no offsets/distortion in longitude that will likely be discernible. For a near-exact determination of the magnitude of errors of which you ask, take Lat/Long coordinates and transform to UTM coordinates on the two different ellipsoids. The difference in Northings will be the nearly-exact magnitude of the computational errors you ask about. (That's more or less equivalent to computing the Meridional Arcs on each ellipsoid with a scale factor.)
We triangulated off the frame imagery and then dropped pass points to the pan. Pan was chopped into chips before stereo compilation.
I once watched Dr. Irene Fischer chew out a 4-star Admiral at a classified symposium. It was pretty funny.
LOUISIANA STATE UNIVERSITY
From: proj-bounces at lists.maptools.org <proj-bounces at lists.maptools.org> on behalf of Irwin Scollar <al001 at uni-koeln.de>
Sent: Saturday, May 10, 2014 10:29 AM
To: proj at lists.maptools.org
Subject: [Proj] Hough Ellipse
I am working on a program for geometric
correction of the Corona KH4, 4A and 4B satellite
imagery which was declassified in 1995 and is now
available from the web site of the USGS & EROS data center.
The panoramic image strips cover vast areas of
roughly 3000 sq. km at 2 to 4 meters per pixel,
depending on the satellite height. USGS supplies
a metadata file with the corner and center points
of each image given in latitude and longitudes.
Image Coverage Models for Declassified Corona,
Argon and Lanyard Satellite Photography, A
Techical Expanation by J. Michael Sélander, in:
CORONA: Between the Sun & the Earth: The First
NRO Reconnaissance Eye in Space. Robert McDonald,
ed. Bethesda, Md.: ASPRS, 1997.
on page 181, it is stated that the coordinate
database uses the Hough Ellipsoid (1960). :
Parameters are given for this ellipsoid in the table:
Although called Hough in honor of F. Hough, it
appears to have been the work of that remarkable
lady Dr. Irene Fischer who lived to be 102 and
see her work incorporated into WGS84. See:
Fischer, Irene. 1959. "A Tentative World Datum
from Geoidal Heights Based on the Hough Ellipsoid
and the Columbus Geoid". Journal of Geophysical Research. 64 (1): 73-84
Can anyone offer some ideas about the amount of
error which would be introduced by mixing Hough
lat/lons and WGS84 lat/lons obtained from Google
Maps/ Google Earth when georeferencing the Corona
imagery for further processing in GIS
programs? Or are Bursa-Wulff or Helmert datum
transformation parameters available somewhere?
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