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Photogrammetry 101: Solving The Trackway Triangle

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I think the casting footage was shot at Bluff Creek and was definitely filmed with the same K-100 camera as the PGF. We have an opportunity to use physical rulers in this footage to estimate distances from the camera using photogrammetry and geometry. This should settle what lens was on the K-100 to shoot the casting footage.

The numbers point strongly to a 25mm lens for the casting footage. So what is the likelihood that Roger switched lenses between the PGF and the casting footage? Just more grist for the mill.

 

If both Patterson and Green used the same lens, why was JM so far behind the supposed trackway?  Just an eyeball estimate shows him 10-20 feet beyond where Patty walked.  If he was following the trackway, why was he so far back?

 

 

You know I don't go for eye-ball estimates. The photo of Green looking thru the Revere camera shows him no where near where Roger was relative to the big log. For some reason he shot the footage farther back from Roger's position. He probably didn't think matching distances from the camera was that important. As long as JM followed relatively close to what was left of the trackway, but not on it, then that should be good enough. Green wasn't an expert filmographer/surveyor/photogrammetrist, after all. We have to cut him some slack here. We were **** lucky to get what he gave us cuz it's all we got.

Edited by Gigantofootecus

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To add..

 

If we assume Patty was 6'1" and McClarin was 6'5" then we can rescale their images and apply the scale factor to calculate the distances from the camera. There is a direct inverse relationship between image size and distance from the camera. It turns out that McClarin didn't follow Patty's trackway too well but at frame 352 he appeared to be only a few feet past the track. Not bad, but Green was at least 10 feet farther back from the track than Roger. IMO, this accounts for the 15 foot discrepancy between Green's site measurements and the distance from Roger to Patty as calculated for a 25mm lens. This misinterpretation of Roger's position at frame 352 is behind the lens controversy. They all got Roger's position wrong by ~10 feet. And Green wasn't even trying to film from Roger's position at frame 352. So how did Green and Dahinden determine where Roger stood at frame 352? Their numbers don't even agree with each other.

Edited by Gigantofootecus

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SweatyYeti

Giganto wrote:

 

 

 It turns out that McClarin didn't follow Patty's trackway too well but at frame 352 he appeared to be only a few feet past the track.

 

 

Giganto, about how far from tree TC-2 do you figure Patty was, when she passed behind it? 

 

The reason I'm asking is because if Patty came within only a foot or two of the tree...then, working backwards from there, Jim must have been at least 10 feet further back than Patty in the scene at the F352 spot...(and possibly further.)

 

 

 

 

This misinterpretation of Roger's position at frame 352 is behind the lens controversy. 

 

 

That may well be part of it.....but I think there is at least one other contributing factor.

 

That error is the 'percentage of the frame height' that Bill measured for Patty. He short-changed Patty's height, by under-estimating where her foot (behind the debris pile) was located. 

Edited by SweatyYeti

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