[GRASSLIST:4360] RE: Matrix Inversion Error when running photo.2t arget in i.ortho.phot o - 2nd attempt

Patton, Eric epatton at nrcan.gc.ca
Thu Sep 16 07:59:45 EDT 2004

Thanks, Michael. I am using Grass 5.3 on a Linux box. I do have Grass 5.7
installed on another PC using Cygwin, and perhaps I should try the
rectification there.

I'll give it a go and post my results on the list.


Thanks for your reply!




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


-----Original Message-----
From: Michael Barton [mailto:michael.barton at asu.edu] 
Sent: Thursday, September 16, 2004 3:26 AM
To: Patton, Eric
Subject: Re: [GRASSLIST:4352] Matrix Inversion Error when running
photo.2target in i.ortho.phot o - 2nd attempt



I don't know what is causing your problem. Which version of GRASS are your
running? Improvements to GRASS 5.7 are happening very quickly. Many of the
main GRASS programmers are at a GRASS/FOSS conference in Japan this past
week and only semi in touch. Probably Markus Neteler would be the best
person as he is currently working on orthophoto rectification. I know HE is
in Japan-giving a paper on orthophoto rectification in fact. If no one gets
back to you, you might try to post your query again in a week.

Michael Barton

On 9/15/04 9:21 AM, "Patton, Eric" <epatton at nrcan.gc.ca> wrote:

I had posted a message regarding matrix inversion errors encountered when
using photo.2target in i.ortho.photo a couple weeks ago, with no response. I
was wondering if anyone could help me with this problem, as the project I am
working on centers on being able to orthorectify aerial photographs as a
part of a coastline erosion analysis program I'm a part of.
I am able to get 6/7ths of the way through i.ortho.photo, with the matrix
inversion error being encountered during the photo.2target phase of the
rectification. I've tried running photo.init, as the manual page suggests,
but this doesn't make any difference, the matrix inversion error always
repeats itself. Even if I create a brand new imagery group, and re-start the
whole process from scratch, I still encounter the inversion error problem. 
Is there any workaround for this problem? I really need to be able to create
a true orthophoto from GRASS, as the rms errors I get when rectifying in
ArcView 8.3 are too high for my analysis!
Any help would be greatly appreciated!!

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