Pentax Photogrametry


Mongoose

Link Posted 23/11/2007 - 21:50
Has anyone else tried photogrametry with the K10D?

My Dad's work has been using Optio WP's for basic photogrametry for a while, but are considering getting a real camera. He and I favour the K10D and we are quite likely to get our way, the weather sealing and value for money sell themselves. The question is what to get to go with it.

In an ideal world a 16-50 and 540FGZ would be at the top of the list. The flash is more than possible, but alas the 16-50 doesn't seem to be available at the moment at any price.

At the moment therefore the initial kit looks like a 16-45 and 540FGZ. Does anyone have any pearls of wisdom to impart in this field?
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Mannesty

Link Posted 23/11/2007 - 22:11
Not being an egghead, I had to look it up too. You can find an explanation of Photogrammetry here.

I think I can safely say that none of us here will have much useful input but I'll happily welcome being proved wrong.

Perhaps Mongoose could elaborate and explain exactly why this science is useful to him/her.
Peter E Smith

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johnriley

Link Posted 23/11/2007 - 22:35
That's an obscure one.

I have one thought and that relates to image distortion. If you are plotting co-ordinates to make 3D models then would I be right in assuming that spatial accuracy would be vital?

Does this then mean that zooms would be quite inaccurate and the only lenses suitable would be macro lenses, and even more likely specially manufactured lenses spoecifically for the purpose? Nikon for example make or made various different fish-eye lenses with different projections. Orthographic projection was one I think?
Best regards, John

Mr. Ist

Link Posted 23/11/2007 - 22:56
An interesting one - As far as the distortion in a lens goes, if you were to use a prime, and take a picture of an object that the software already knows the shape of, the distortion would be calculate and the repeatability increased significantly...

If the pentax isn't up to it : www.gom.com

Mongoose

Link Posted 24/11/2007 - 16:59
Thanks for the interest guys, to be honest I didn't think anyone here would have tried it, but was worth asking.

My Dad is a Land Surveyor (I work for the same company as a Graduate Civil Engineer). He uses rectified photography (photogrametry was the wrong word to use really, my mistake) for elevations. A few frames on the camera and a few control points taken with a Theodilite (A Leica 700 series, but could easily be a Pentax R300 ) make light work of planning grade elevations. They aren't perfect, but are more than adequate for the requirements of most clients. When they aren't, it's time to deploy the laser scanner.

With a cheap point and shoot you can get passable resolution for rough elevations.

With an SLR and a high quality lens with known distortion characteristics, you can be really quite acurate. We have repeatedly demonstrated that a *istDL2 with a 28mm prime is far better than the optios, but up to now we've never been able to convince the boss that the outlay is worth it.

Now he has a job which can only be realistically done with a combination of the mighty laser scanner and some serious rectified photography.

Primes are ideal of course, but the versitility of a short zoom might swing things that way.

Does anyone have any experience of the Pentax 14mm prime?
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Mongoose

Link Posted 03/12/2007 - 21:18
we had a meeting today with a guy from a company which makes software for full on 3D modeling from photographs. We showed him the K10D and he was very impressed, especially by the viewfinder and built in SR. Then we told him it was dust sealed and now he plans to recommend them
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Kim C

Link Posted 06/12/2007 - 12:53
If you need the angle of view, the 14 is a very good lens. I haven't tried it against the 16-50 but I have been very impressed with it so far.

Kim
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