Stand back a measured distance, read the angle to the top and the angle to the base, and the height follows. It needs no camera, no calibration and no software, and on a cliff you cannot climb it is still the most accurate thing available.
Take the angle from two points on the same line, a measured baseline apart. The height follows from the two angles alone — the baseline is the only length you need, and it can be paced along ground you can walk.
A photograph on its own has no scale at all — a model and a mountain make the same picture. Give it one known length, or the distance and the lens, and every pixel becomes a measurement.
This assumes the face is flat and square to the camera. Anything oblique is foreshortened, and anything nearer the lens than the rest is magnified — which is why a scale bar has to be on the face itself, not leaning at the bottom of it.
Two photographs from a measured distance apart give depth, because a near point shifts more between them than a far one. That shift is the parallax, and the depth is Z = f·B/d — focal length times baseline over the shift. It is how every stereo pair, every drone survey and both your eyes work.
Focal length in pixels, not millimetres: it is the image width divided by twice the tangent of half the field of view. The conversion is done for you on the planning tab.
A reconstruction fails in the field, not in the software. It needs overlap, convergence and a scale bar — and no amount of processing recovers a set of photographs that lacks them.
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Once the face is measured, the planes on it are read in Structural analysis and their stability in Geotechnical. Measuring grains rather than a cliff — the same idea at a hand-lens scale, with a coin for the scale bar — is in the Loupe.