The only code the ADA requires for that type of extinguisher box is that the lowest leading edge be mounted at or below 27".
I have attached four more images, this time of the dutch door/alcove hallway. The lens distortion has been corrected, and once again I'm using standard door installation heights of 84". You can see in image 1 and 2, the fire extinguisher box appears to be mounted at code height of 27". In image 3, the subject is just about to enter the alcove. This is the last frame where the bottoms of his feet are unobscured by shadows. The frames just after (with the headlamp reflection on the wall) are not useful for this technique, since his feet are not visible. In image 4, you'll see his heel lands exactly on the edge of the tile floor, in line with the bottom edge of the wall facing the camera.
The lens distortion in these images were more complicated to correct than the tile hallway. It took a couple days, but in the end I still ended up with a fairly consistent height of 71-72" (total with gear). The more time I spend on these images, the more narrow my margin becomes. But until we know the exact doorway height, these are only
estimated numbers.