This thesis describes an algorithm for 3-D pose calculation of known objects from a single perspective view. The pose calculation algorithm consists of four main stages: pose candidate generation, candidate verification, optimization and reliability analysis. In the first stage, pose candidates are generated by matching model and image triangles. An important sub-problem, the so-called 3-point perspective pose estimation problem, is solved numerically. Pose candidates are verified by matching model and image features. The first accepted candidate is then optimized. Three optimization methods are considered: Newton-Raphson, simulated annealing and robust M-estimate using Lorenzian distribution. The reliability estimates are based on covariance analysis. Uncertainties due to both model and image noise are taken into account. A structure optimization method to reduce modeling noise is also presented. The algorithm was implemented on two parallel computers, a Connection Machine-2 (CM-2) and a Hathi-2/16. The Connection Machine is an SIMD machine whereas the Hathi-2/16 is based on the MIMD architecture. To evaluate the speed and accuracy of the algorithm, several experiments were performed using both synthetic and real images. In simulations, the accuracy of the calculated pose, the validity of uncertainty estimates and the effect of dynamic modeling were studied using a polyhedral test object whose maximum distance between any two vertices was 175 mm. Simulations showed that for the distance range from 0.5 m to 2.75 m, the standard deviation of the rotation error ranged from 0.5 degrees to 3.5 degrees when the standard deviation of image and model noise was 1.5 pixels and 1.5 mm, respectively. For the x-and y-directions the errors ranged from less than 2 mm up to 10 mm, and for the z-direction, from a few millimeters up to 75 mm. Much better results were achieved at the lower noise levels. The processing times on both the machines were approximately the same. On the Hathi-2/16, when all the 16 processors were used, the pose calculation time ranged from 0.376 s up to 0.814 s. For ease of programming the Hathi-2/16 was better than the CM-2, and it was also considerably cheaper.
|Award date||18 Dec 1992|
|Place of Publication||Espoo|
|Publication status||Published - 1992|
|MoE publication type||G4 Doctoral dissertation (monograph)|
- 3d analysis
- parallel computing