From - Wed Jan 9 16:24:24 2002 Return-Path: Received: from post2.inre.asu.edu (post2.inre.asu.edu [129.219.110.73]) by imap2.asu.edu (8.11.0/8.11.0/asu_cyrus,tcp_wrapped) with ESMTP id g09I15O25722 for ; Wed, 9 Jan 2002 11:01:05 -0700 (MST) Received: from conversion.post2.inre.asu.edu by asu.edu (PMDF V6.1 #40111) id <0GPO00G01NDSC7@asu.edu> for arrows@IMAP2.ASU.EDU (ORCPT ramon.arrowsmith@asu.edu); Wed, 09 Jan 2002 11:01:04 -0700 (MST) Received: from smtp.asu.edu (smtp.asu.edu [129.219.110.107]) by asu.edu (PMDF V6.1 #40111) with ESMTP id <0GPO00EFCNDS0M@asu.edu> for arrows@IMAP2.ASU.EDU (ORCPT ramon.arrowsmith@asu.edu); Wed, 09 Jan 2002 11:01:04 -0700 (MST) Received: from general3.asu.edu (general3.asu.edu [129.219.10.243]) by smtp.asu.edu (8.11.0/8.11.0/asu_smtp_relay,nullclient,tcp_wrapped) with ESMTP id g09I13N07331 for ; Wed, 09 Jan 2002 11:01:03 -0700 (MST) Date: Wed, 09 Jan 2002 11:01:04 -0700 (MST) From: stephen.holloway@asu.edu Subject: Re: camera parameters In-reply-to: <3C3C5CC4.B233C922@asu.edu> X-Sender: nehpets@general3.asu.edu To: Ramon Arrowsmith Message-id: MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII Ramon, The simple answer is that it can't be done without the camera parameters. We ran into the same issue with those air photos over the LY4 trench site. The unpleasant solution is to use point to point rectification with a georeferenced topo map. The complex answer is that it depends on: -how much experience the person has with aerial photography (can they recognize a Wild from a Zeiss, Fairchild, or Leica, to help make educated guesses?) -the photos themselves (do they have fiducial marks, bubble levels, date stamps, border patterns, any printed info? if so, can be used to pin down at least the make if not the model) -how many photos are involved (if only 3, is it worth the hassle?) -what resolution is needed (brute rectification can be perfectly adequate) -the history of the air photos (where are they from? is there a paper trail? if a city, state, or national agency, they could have the summary report with the camera parameters or have records of the contractor who can then be contacted for the camera parameters; if a rural unpopulated area, there may be only one or two aerial photo contractors who hopefully have records) -helpfulness of others (Landiscor, a private aerial photography company, was extremely helpful in helping me hunt down information on some Union Hills photos I had from the state survey) Even after all that, you will need ALL the camera parameters. In my limited experience, you will never be able to guess. If you make incremental changes in one variable, you will not see incremental improvements in the image. All that said, I have not personally used Orthomax in over a year and a half, and perhaps they have a better system in place, but this is what I know about it. I hope that helps. Steve On Wed, 9 Jan 2002, Ramon Arrowsmith wrote: > Steve, > I don't know if you know this, but for Imagine and Orthomax, one needs to > know the camera parameters to improve the images from aerial > photographs. Perhaps you remember her, but Anne TIllery who was a > student here, is now at UNM and she has some airphotos from the usgs > (NAPP) and would like to try to generate DEMS using orthomax. She does > not have the camera parameters. Do you know any easy way to determine the > camera type/parameters (given that it is not written on the airphoto)? > thanks, > ramon > > > -- > Ramon Arrowsmith ramon.arrowsmith@asu.edu > Associate Professor Office: (480) 965-3541 > Department of Geological Sciences Home: (480) 777-8371 > Arizona State University Fax: (480) 965-8102 > Tempe, AZ, 85287-1404 USA http://www.public.asu.edu/~arrows > >