Calibration technique for measuring absolute dimensions of shape-from-texture 3D surfaces

Abstract

We propose a calibration technique to measure absolute dimensions of recovered shape-from-texture 3D reconstructions. Absolute dimensionality allows volumetric measurement on the surface reconstruction, thereby quantifying change in growth of object such as the growth of corals. Cylinders with known radii were used as reference objects to compute for pixel-to-length conversion. The geometry of circles is applied to this technique to compute for the corresponding radius and center of the cylinder profile. Results show a maximum of 9.87% and minimum of 0.17% difference in the calculated radius test cylinders. The technique requires that the reference object be imaged with the object of interest and that calibration should be performed every image capture.