BASE "photography"

[yuri_base 1]

Posting a pic here simply to link to it from basejumper.com - that buggy site does not allow to make attachments (randomly).

Link to post there:

Simple height measurement method

Sorry for the offtopic, the subject does have some relevance to photography.

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[Laszloimage 0]

Yuri,
It could only work if the person was standing right next to the bridges's pillar. Otherwise the calculation won't be accurate beacause the distance between the known value (the person) and the angle of view of the lens allows infinite variations.
Counting the pixels is a good idea. But the only accurate calculation would be if we know the actual angle of the view and the distance between the camera and the known person. Based on that we can calculate the hight of the object in the back using triangulation (Tg, Ctg, Sin, Cos....)
Otherwise we're going to be a victim of optical illusion.
-Laszlo-

[yuri_base 1]

Laszlo, it works and the principle behind it is solid - it's just simple geometric proportions. Check out the link above, can you prove that formulas are wrong? The lens needs to be linear (i.e. not wide angle). If you take a picture of a yardstick, 1 inch in the middle of the frame should be as long as 1 inch at the edge of the frame. I took the picture with Canon 50mm f/1.4 lens, which is known to be high-quality, and Canon 20D, which crops the field of view by 1.6x factor (which further limits the nonlinearity). But even with P&S cameras, it'll still work and is accurate enough for the intended purpose.

Yuri

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[Laszloimage 0]

...try to repeat the whole photo taking process exactly the same way, with same settings, with the exact same equipment, except ad one more thing. Try to take a second shot when the person is in the image, but before you do that ask him to make ten steps towards the camera.
Make the calculation with first shot with the person in image, and then another one when he's a few feet closer to your lens.
Trust me, in the second calculation that BASE object will become less tall.

[yuri_base 1]

Of course, if the person is not in the spot where you took the first picture, the calculation will be wrong. But why would you do a wrong thing when you can do the right one?

In this particular example, I took the first picture while standing next to the trash can. Then I put the camera on a tripod about 100ft farther away from the bridge, turned on the timer (10 seconds) and ran back to the trash can. I did the right thing and got the right result.
Anybody try this method? If you can prove that it does not work, I'll buy you a jumpticket.

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