Three-dimensional reconstruction of objects with large depth variations

Abstract

ABSTRACT We present an active triangulation based system for 3D reconstruction of objects with large depth variations which are placed on a rotary table to obtain the entire 3D view. We project Fresnel diffraction from an edge to generate an illumination pattern with large depth of focus on the olectsurface. The frontier line separating dark from bright areas of the diffraction pattern is used for linesectioning of the object, and the height profile is obtained through triangulatioit Three dimenSiOnalreconstructions are illustrated for various objects having 10 cm maximum depth variations: the depthmeasurement accuracy is 0.36 mm for an object average distance of 350 mm. 1. INTRODUCTIONSeveral techniques can be used for rangefindin2, each one contrasting by its specific qualifies: accuracy on the range measurement, lateral resolution, standoff distance, field of view, acquisition time, senSitivity to external disturbances, ease of automatiOn, etc.. Each range$inding system may have aspecific application in thdustry'4 but yet a true comparison of their relative performance remainsdifficult. In some manner, Besi attempts to quantify the performance of a range4inding system usinga figure of merit which takes into account range resolution, lateral accuracy and acquisition time. Aclassification/comparison of all existing 3D systems was then made possible even if cost was notconsidered. For a given application, for example if time is not important but cost becomes a majorfactor, the best choice might sometimes be a system with a lower figure of meritOne active range-fmding technique consists in projecting a sheet of light on the object surface6