SCAN IN A BOX
Guide to the Ideal 3D Scan
Part I – General considerations
Structured Light Technology
3D Model generationIn order to achieve a complete 3D model, the whole surface must be acquired in different frames that must be aligned and converted in a triangular mesh, the digital model. (ref. fig. 4).
TIP! A good optical set-up and good calibration effects a good 3D model generation. This setup steps have to be performed at the first 3D scanner usage and afterward only if you change the field of work, as described in the Quick Start Guide (ref. fig. 5). It's strongly advised to follow the Quick Start Guide step by step.
Optimal ScansIn order to obtain an optimal 3D reconstruction the following factor that might influence the result of the process must be taken into account:
- the environment light;
- the object characteristics such as material, color and shape;
- the background.
Environment lightThe ideal condition of environment light for the 3D scanner usage is that of a room with a normal day light, in which the only artificial light is the one reproduced by the projector of the scanner (ref. fig. 6).
It is recommended a medium intensity and homogeneous light, it should not point neither directly on the scene (ref. fig. 7) nor to the 3D scanner (ref. fig. 8.).
It is likewise important not to have shadow projected to the object (ref. fig. 9).
The direct sun light may cause some problems if it interferes with the projector light, therefore it is better to avoid the scanner usage in rooms in which the sun light is directed on the scanned object. It is really important to have a controlled environment light, in this way a not optimal scan output can be avoided. These are some issues that comes from an unfavorable light environment:
- waves caused by some light reflected on the object (ref. fig. 10);
- roughness on the scan surface that are caused by overexposure (ref. fig. 11);
- a scan with orange peel effect, that is called “noisy”, when the projector light is lacking compared to the environment light (ref. fig. 12);
- in the worst case, a scan with a lot of missing part that leads to holes on the surface of the digital model (ref. fig. 13).
Object featuresThere are some kind of materials, colors and shapes that cooperate perfectly with the digitization procedure and others that have some critical issues.
Figure 19: texture view of the 3D Scan with Grey before and Very Dark after. Please notice the improvement in the darkest part of the hair.
The Color Calibration is conditioned by the environment light where the scan is taking place. The condition must be verified as optimal before proceeding. It is advised to execute the Color Calibration before to start the scan sequence, otherwise color differences can be observed in the overlapping areas of the 3D scan (ref. fig. 22-23).
It is recommended to take advantage of the tripod versatility, considering that what matters is the distance between the projector and the model, which is easily verifiable in the software with the LIVE mode (using the yellow crosshair) (ref. fig. 27).
TIP! A worktop with high contrast respect to the surface of the object may facilitate to reach an optimal result and can help to easily select which point of view is needed to complete the surface scan. It is recommended to use a dark opaque surface, such as a black mat, as working plane (ref. fig. 30).