The authors present an active triangulation-based range finding system composed of an independent laser system generating a sheet of light projected on the object to be measured, which is placed on a linear or a rotary table driven by a personal computer. This computer includes a video digitizer board to which two cameras, looking at the scene from both sides of the sheet of light, are connected. Besides its low cost, this system has several advantages over similar systems. First of all, two cameras are used to limit the occlusion problem, and a method is proposed to integrate range data obtained from these cameras into a single range image. The calibration of each camera is very simple, provides subpixel accuracy, and is performed only once as the laser or the camera does not move. The data acquisition uses an interpolation technique that produces very accurate depth measurements. The system also provides intensity data in registration with the range data. The application of all these techniques is illustrated by showing numerous examples of the range and intensity data acquisition from various complex objects.>

The authors address the following problem: given a camera moving in an unknown environment, they want to obtain a 3-D description of the environment. A unifying approach is presented by deriving a unique formalism to process uniformly different but complementary features, namely points and linear segments. Different concepts for tracking features are given: (1) 2-D tracker-2-D features are tracked using an order one dynamic model for their evolution; (2) 2-D+estimation tracker-3-D fusion of 2-D features is performed recursively, and then the value predicted at time t for these 3-D features is projected at time t+1 onto the camera focal plane and replaces the dynamic model used in the 2-D tracker, allowing the introduction of 3-D information into the 2-D feature tracker without prior knowledge of the environment; and (3) 3-D tracker-the 2-D tracker disappears, and all computations are 3-D. The 3-D tracker combines the simplicity of the 2-D tracker and the efficiency of the 2-D+estimation tracker. A description is given of the mechanisms of fusion that integrate 2-D measurements into an estimate of the feature 3-D parameters. Uncertainties are taken into account through extended Kalman filtering. Feature parametrizations are chosen to simplify the linearization process and ensure numerical stability.>

The authors present an active triangulation range finding system composed of an independent laser system generating a plane of light projected on an object placed on a rotary table driven by a personal computer. This computer includes a video digitizer board connected to a camera looking at the scene. Besides its low cost, this system has other advantages over the comparable existing systems. First, the authors have designed a simple, fast and accurate calibration procedure which does not require any knowledge about the camera parameters or the relative position of the camera with the laser plane. Furthermore, this calibration procedure is performed only once, ensuring stable and accurate results. The result of the scanning of a given object is given in cylindrical coordinates. Choosing different viewpoints, Cartesian range images of the same object are computed in order to show, with shaded and perspective views of the scanned object, the quality of the results.>