How Accurate Is Photogrammetry?
The short answer is that photogrammetry is precise and provides accuracies comparable to those achieved by other large-volume, high-accuracy coordinate measurement systems. Typical accuracies are 25 to 50 microns (0.001 inch to 0.002 inch) on a 3-meter (10-foot) object. The long answer is a bit more elaborate, because photogrammetric accuracy depends on several interdependent factors: 1) camera resolution, 2) the size of the measured object, 3) the number of photographs taken and 4) the geometric layout of the camera stations (camera locations) relative to the object and to each other. Based on these factors, accuracies can vary accordingly. To get higher accuracy, you need some combination of higher resolution, smaller size, more photos and/or wider geometry. However, as a rule of thumb, if you use the Inca3 camera and take six to eight photographs with good geometry, and each photograph sees the entire object, you should obtain accuracies of 25 to 50 microns (0.001 inch to 0.002 inch
