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Has anyone ever camera matched a render to an iphone picture?
show user profile  Boing
I do a lot of photomontage work for planning applications, dropping new developments into existing site photos and therefore having to match the Max camera with the physical one.

Normally I have no problems but recently a client gave me a series of vertical (portrait) site photos to be stitched into a panoramic of his site, problem is, they were taken on an iphone 4 and I cannot get my cameras anywhere near to lining up.

Here's some info on the phone.

The sensor is 4.54 x 3.42 mm with a 3.9mm lens, when I put 4.54mm into the film gate and 3.9mm into the lens size it doesn't line up, the reference points I've modelled into my scene are too far away by quite a margin. Then I had an idea, since the photos were taken vertically I put the smaller depth measurement for the sensor in (3.42mm) and it works.

Problem is, it was a guess and I don't really understand why it works and as there is a small chance these applications can be fought, I have to be able to explain my methodology, which I currently can't. So can anyone explain the logic of why this works?

[edit] I've tested it with a horizontal and vertical SLR shot and it seems to work, the vertical shot requires you to use the sensor depth rather than width. Still not 100% clear on why though, I'm guessing the film gate is the horizontal measurement of the camera aperture irrespective of the camera orientation.
read 1767 times
7/18/2012 3:25:44 PM (last edit: 7/19/2012 5:49:25 PM)
show user profile  Bolteon
in this case id say fuck doing it right... just eyeball it.

-Marko Mandaric

read 1720 times
7/18/2012 10:20:12 PM (last edit: 7/18/2012 10:20:12 PM)
show user profile  Stephen R.
Because the phone was turned sideways when the picture was taken?

read 1717 times
7/18/2012 10:33:02 PM (last edit: 7/18/2012 10:33:02 PM)
show user profile  Garp
My thought too.

read 1711 times
7/18/2012 11:00:01 PM (last edit: 7/18/2012 11:00:01 PM)
show user profile  reeves1984
I'm not sure what your question is, I think you solved it!

Simon Reeves - VFX Artist & Blog
twitter <-- I work here

read 1689 times
7/19/2012 8:46:43 AM (last edit: 7/19/2012 8:46:43 AM)
show user profile  STRAT
photos are photos.

Problems will always arrise when trying to camera match stitched photos together - all sense of correct depths, field of views, perspective/vanishing points etc etc disappear, whether using slr cams or mobile phone cams.

This is because, in general, each photo was taken from a slightly different position. This means you cant stitch a 'true' photograph together.

The only sure fire way of making a 'true' panoramic, however long or short, and in either portrait or landscape, is to use a tripod stationed in 1 spot.

A human acting as a tripod isnt a substitute. So, as per normal, just eye up best you can.


read 1684 times
7/19/2012 9:37:42 AM (last edit: 7/19/2012 9:38:48 AM)
show user profile  Boing
Bolteon: can't eyeball it, £1.5M housing development depends on getting planning permission.

Stephen: yeah That's what triggered my guess, that the film gate measurement on the vray physical cam isn't necessarily the widest dimension on the sensor but whichever one is horizontal when the pic is taken. As I say, I tested it with an SLR and I had to substitute the sensor height for the width when shooting in portrait to make it work.

I solved it in the sense that it works but I would like to understand why it works in case my methodology is questioned at a planning appeal.

Strat: Yeah these things are never perfect with multi camera shots but the planners don't like wide angle lenses as they distort the perspective too much and make buildings seem smaller than they would with the human eye.

reading my post again I don't think I made it clear, my issue isn't making the shots line up with each other to make a panoramic but making the renders line up with the photograph they are being inserted into. It's matching the vray cam to the physical cam that's the problem, normally you put the widest sensor dimension into the film gate but for this I had to put the smaller dimension in. My guess is because the iphone was shooting in portrait rather than on it's side in landscape but I'd like to know I can explain that technically if I have to.
read 1661 times
7/19/2012 5:48:58 PM (last edit: 7/19/2012 5:50:56 PM)
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