...but I remember reading somewhere once that the ancient Egyptians built their pyramids so that the slopes of the monuments would rise at the same angle as the angle which cones of fine desert sand tended to assume, believing this made them more stable.

I did my photogrammetic work in both Florida, and at another firm I worked at in Tennessee.
The relief is very different in the ridge-and-valley country of Appalachia to that in flat Florida and provided very different challenges to the stereo plotter operator. In TN, you had to carefully adjust the equipment so that the high and low points of the photogrammetric model fell entirely within the instrumental vertical constraints of the instrument. In Florida, you could afford to be sloppy, since the potential delta-Z was well within the high-low limits of the equipment and the photo geometry.

I do know the Z value was deliberately exaggerated by the optics so that the photogrammetrist was able to make accurate measurements of very small elevation differences. For example, when a contour line crossed a road built on a grade, it was always convex down-slope,to reflect the fact that the
crown of the road was higher than the drains along either side. If the road had a curb, the contour line would disappear as it traveled along the curb until it hit the appropriate elevation, whereupon it would reappear and continue across the road. If a river or stream crossed a model, the water level was measurably higher upstream, even in flat FL. We often used lakes, which were of constant elevation throughout, to help level models accurately when our ground survey was off or lacking in sufficient elevation data.

I mention this to give you some idea how accurate the photogrammetric technique can be.
In Florida, particularly, it was essential to get the drainage right to protect future development from flooding.

Thanks for the trip down memory lane. I have great respect for this sort of "blue-collar" work. It financed my graduate school, and convinced me that you didn't have to be a college weenie to do work that required intelligence and dedication. My colleagues, pilots, photographers, photo lab techs, and draftsmen, exhibited great craftsmanship and integrity. I was very proud to be accepted by them and to work alongside them.