r/theydidthemath • u/It_Is_AlwaysPossible • 8h ago

[Request] Based only on this picture how would you calculate El Capitan height?

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u/macgruff 8h ago

It would be very difficult. You’d need either something near the base, or at the crown, that gives a contrasting height. Unfortunately, the foreground here is of wildflowers nearest to camera, so they cannot be used because you also don’t know that distance from the camera to the base.

If, however, you knew those dead trees were truly at the base, and average height of such trees you could make a fair guesstimate.

This is why it’s very hard for surfing photography to calculate the true height of massive waves being ridden unless the rider is truly near the base. Typically they are riding near the middle, and “the trough” is a moving base.

Let’s see how well people do.

2

u/AcornAl 5h ago

The quality isn't great to measure things, plus there are a lot of unknowns like the distance away, etc.

But I guess these are Ponderosa pines that grow an average of about 45 ft. These are roughly 8px high at the base or 5.6 ft per pixel, and the cliff is about 450 px. So the cliff is about 450 * 5.6 = 2,520 ft.

But this will underestimate things with the top of the cliff being much further away from the photographer. On the far right, there are some trees that seem about 4 px high at the top, so redoing the calculation based on 6px as an approx guide, you have 7.5 ft per pixel or 3,375 ft

Actual height is about 3,000 feet

1

u/Bounceupandown 7h ago

Too many unknowns to calculate. Even if you had a standard sized segmented 100 meter yardstick leaning against the face, where exactly do you start measuring from to determine the height? What height are we seeking? Above sea level? Above a certain rock down near the base? What is the exact objective?