Scanning complex objects.
A process of scanning a quite typical order for 3d scanning is described below. It is a decoratory element of wood. Object height without the projecting bar with holes is about 400 mm, whereas its full height is 700 mm and width - about 190 mm.
Scanning difficulties were as follows:
• The object surface was covered with a dark but slightly glaring paint. This led to noise data increase and hole origin at glaring places. Matte coating should have been applied before scanning in such case.
• The object had smooth forms and small decoratory elements as well. Using a maximal scan area would have not allowed quality scanning of small elements.
• The object possessed a high degree of symmetry, which could have created difficulties during finding correct positions of separate fragments.
• Painting the object and sticking markers to it were unacceptable as the object was a thing of value.
An optimal solution was found as a result. Scanning was done by the VTScanner with scan area 200. The scan area was slightly smaller than the object itself, but this allowed to make quality scans of small decoratory elements, though scan fragment number was increased. The object itself was scanned by portions. Separate fragments were matched by means of an auxiliary element, a black board with chaotically attached markers. In order to increase reliability and convenience, a reference net consisting of board marker coordinates was prepared by the scanner itself. Due to the fact that markers during scanning were identified by the 3d scanner software automatically, fragment matching was done without operator assistance. This significantly simplified the work.
The object was laid on the auxiliary board in several positions with turning it each time around its axis. 7 positions were obtained. In each position scanning was done at angle to the object axis by portions: from bottom to top, then from top to bottom. 6 automatically matched fragments were obtained for each run top-bottom/ bottom-top run.
The picture shows the scanning process – 6 fragments are scanned in one of the position from bottom to top.
14 groups by 6 fragments in each were obtained. These groups were cleaned of visible foreign elements, such as fragments of the auxiliary board.
2 groups by 6 fragments scanned in opposite directions.
Cleaned groups of fragments were united in a common reference system. The object had strong symmetry. In order to correctly find positions of fragment groups against the other groups we used the unique geometry of the protruding bar with holes. Total quantity of triangles in all fragments made 72 million. The 3D scanner software allowed easy working with such large data volumes.
Fragments are gathered.
Farther, a single surface of all points and triangles was generated and saved in STL format. Triangle quantity in the finished STL model made above 6 million. The obtained STL model is a result of 3D scanning and might be used for editing, transforming into CAD formats or direct sending to prototyping systems, for instance, to a 3d printer or a 3d mill lathe.
Made on