direct link: http://www.creaform3d.com/newsletters/december2010/index-en-full.html?utm_source=newsletter&utm_medium=email&utm_campaign=december2010#truc-2
TIPS & TRICKS - Creaform Body Digitizers
Improved Temporal Phase-Shifting, Moiré Technique
From a camera angle, a projected fringe pattern is deformed by surface relief. During 3D data acquisition, a number of video images are captured with a determined phase-shifting (displacement of the fringes). The depth measurement of a point on the object is calculated based on the variation of light intensity of each corresponding pixel
Impact of ambient lighting
To acquire optimal 3D data, it is essential that the fringe pattern projected on an object’s surface and captured on video camera show a good contrast. To reach good contrast level, the intensity of ambient lighting should not exceed that of the projected fringe pattern. We strongly recommend avoiding strong ambient lighting such as outdoor lighting, direct daylight from a window or any other strong light source.
Because a normal fluorescent light oscillates at local electricity frequency (50 or 60Hz) and to avoid the “flashy” effect of fluorescent lights it is recommended to avoid the use of florescent light as ambient lighting when recording images at 20 to 30 frames/s. On the other hand, very high frequency halogen, tungsten or fluorescent lights (a few kHz) can be used as ambient light sources. Plus, make sure that the ambient lighting remains unchanged during the capture sequence.
How to adjust fringe pattern intensity
To adjust fringe pattern intensity, launch the software PCS Setup and choose the Advanced – Camera Adjustment – Fringes option:
For example, the following images show different results of fringe pattern with adjusted intensities:
 |  |
|---|---|
| Good intensity level and good contrast | Under-exposed |
 |  |
| Over-exposed | Low contrast due to strong ambient lighting |
