A. Pentland et al., SIMPLE RANGE CAMERAS BASED ON FOCAL ERROR, Journal of the Optical Society of America. A, Optics, image science,and vision., 11(11), 1994, pp. 2925-2934
We describe research on two imaging range sensors that use defocus to
estimate range. One technique is completely passive and provides dense
range measurements in textured areas with an rms error of 2.5%. This
method can be useful when stereo is unreliable because of corresponden
ce errors or when imaging geometry prevents the use of multiple viewpo
ints (e.g., microscopy). The second technique uses structured light an
d provides dense range measurements with an rms error of 0.5%. This me
thod can be useful when imaging geometry prevents the use of multiple
viewpoints and for acquiring range imagery of rapidly moving objects,
as the structured light can be delivered in a single stroboscopic flas
h.