Surface extraction

From the 9 scans we took we obtained 9 sets of point clouds in 3D space. To create a textured 3D model we needed to extract a surface from these points.

We started by removing unwanted background using the Cyclone software. We then meshed all scans individually. This approach resulted in as many surfaces as scans, in our case 9. But it was our desire to extract a single surface by merging the meshes together, or by merging the point clouds together and then meshing the resulting set. So we attempted this task again using another piece of software which is able to accomplish the latter: Spider. Spider creates a mesh from an unorganized pointcloud, but appropiate settings have to be set to avoid a large number of holes. Even the best results from Spider had many holes and we were not able to remove all of them.

On our second trial we started by building a surface using VripPack. This package uses a volumetric approach to surface reconstruction. There were a number of things we had to setup  in order to use Vrip. First we had to convert our Cyclone point clouds which are stored in the ptx format to the ply format. This was accomplished with the ptx2ply program. This program produced a configuration file for vrip which has the 9 point clouds in ply format as well as the transformation of each point cloud relative to the first point cloud ( also known as the home view ). We then set up Vrip to use a voxel resolution of 1cm since this is the scanning resolution. We also set the ramp width for a width of 4cm. VripPack was by far the quickest ( less than 30 seconds ) software to build our mesh. The resulting surface contained a large number of holes, especially in highly occluded areas such as the thighs, the chest and the hands. We imported this surface into Spider and interactively filled the missing holes to produce a water tight model!

The final model had 312963 vertices and 624920 faces. These are very large memory requirements and we reduced the mesh to have 52369 vertices and 104000 faces so we could interactively render the surface.


Cyra Cyclone meshes

Spider meshes

VripPack + Spider