Photogrammetric characterisation of concentrator surfaces
SG4 dish with retro-reflective targets
for photogrammetry measurement of mirror panel alignments.
This technique uses multiple photographs taken from different
positions to deduce the three dimensional shape of a surface
such as the mirror in a solar concentrator. Optical targets
are placed or projected onto the surface to provide reference points
('targets') whose spatial coordinates can be determined with
high accuracy—a precision of better than 1/100,000
of the scale of the object being measured can be attained.