RVidia - automatic reverse engineering of laser scanned point clouds into CAD models in STEP and IGES format  

Working with the point clouds

You start with a point cloud. The number of points is theoretically unlimited. Practical limitations are system configuration and size of the available memory. With 2 Gbyte RAM you will be able to deal with point clouds up to 1.000.000 points. R-Vidia offers various tools for point clouds registration and fitting with each other. You can join mesh with point cloud, point cloud with other point cloud, change the transformation (rotation & translation) and reverse point cloud into a mesh. Number of points can be reduced by rejecting duplicated points within a user defined tolerance and other decimation criteria.

Working with the meshes

Creating a mesh from point cloud is controlled by number of parameters defining the resulting mesh quality. You control minimum triangle angle, dihedral angle and boundary definition all within specified absolute tolerance. The resulting mesh can be further analyse to form water tight volume (sewing) and edited on a level of triangle definition (edges, vertexes) as well as global functions such as fill hole(s). Mesh can be further smooth using various criteria (mean filtering, angle median filtering or Laplasian flow) or simplified to target amount of triangles (%) or numerical tolerance (e.g. 0.005 mm).

Patch division

The patch division process finds automatically the optimal mesh division. A feature recognition algorithm is used to automatically identify mesh parts convertible into analytical forms such as planes, cylinders, SOR (surface of revelation), sphere, torus, and cones. Those patches will be converted not to NURBS, but analytically defined parametric surfaces. The remaining patches are converted into NURBS. The amount of patches is controlled and will depend on the specified accuracy for the reverse engineering process. The accuracy is controlled on the patch boarders and in the middle of each patch by measuring the deviation between resulting NURBS surface and original triangulation. The objective is to produce patches fitting with each other and forming a water tight solid in the CAD system. Reverse engineering results can be overlaid with the original triangulation and point cloud to verify the results. R-Vidia is optimised to work with multiple data structure such as point cloud, mesh and parametric NURBS, resulting in high performance and ease of use.

R-Vidia is successfully used in all type of reverse engineering applications including free form parts, mechanical parts and combination of both. The application areas vary from medical to mould design.