Got a request to survey building facades for a renovation project. They want accurate measurements of windows, doors, and architectural features.
I know I need oblique angles but not sure about the optimal setup. What angle off nadir works best? How much overlap? Any gotchas with the photogrammetry processing?
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Sign inDon't forget a nadir pass too. The combination of nadir + oblique gives much better results than oblique alone. I usually do one nadir grid, then four oblique passes (N/S/E/W facing).
For facades I typically fly at 45 degrees off nadir. Higher overlap than usual - 80/80 at minimum. The key is consistent distance from the building surface.
Process as a 3D model, not ortho. Pix4D's 3D Maps template works well.
Watch your sun angle. Shadows on facades really mess with the photogrammetry. Overcast days are ideal, or fly when the sun isn't creating harsh shadows on your target facade.