Patton, Eric epatton at nrcan.gc.ca
Thu Sep 9 10:50:02 EDT 2004

Hello everyone,


Is there any way to escape from recurring 'Matrix Inversion Errors' when
using photo.2target in i.ortho.photo? The GRASS manual entry for
photo.2target mentions running photo.init as a remedy for this error,
however I've done this already entering in as much information as I could
from the flight report for my air photo. I've tried creating a new image
group, and re-running all the steps in i.ortho.photo, only to have it crash
on a matrix inversion error on step 7, after about 12 control points get


I've entered in values for the Initial Camera Exposure X,Y,Z coordinates, as
well as estimates of the Omega, Phi, and Kappa parameters (0.01 degrees
each) in photo.init. I had no idea what to enter for the 'A Priori Standard
Deviations', so I've left these all at 0. If I am working with a 1m
resolution air photo, and a 1m res DEM, what would be reasonable estimates
for these standard deviations?


Any help would be appreciated!





Eric Patton


Technologist, Geo-Spatial Data Services

Geological Survey of Canada (Atlantic)

Natural Resources Canada

Bedford Institute of Oceanography

Dartmouth, Nova Scotia, Canada B2Y 4A2


Postal address: P.O. Box 1006

Courier address: 1 Challenger Drive


Telephone: (902)426-7732

Facsimile:  (902)426-4104

E-mail:        <mailto:epatton at NRCan.gc.ca> epatton at NRCan.gc.ca



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