The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5. Beijing 2008
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Figure 1. Craniofacial Spatial Data Acquisition System -
Conceptual Design
In Figure, Cl to C8 shows the location of camera 1 to camera 8,
while LI and L2 show the location of laser scanner 1 and laser
scanner 2 (Figure 3). Camera 3 and camera 6 (Figure 4) was
setup in convergent mode at lower position to allow the scanner
to emit the laser light onto craniofacial surface. Both cameras
o
were also rotated 90 to allow the implementation of role
diversity rule in the system.
The approach implemented in the developed system is unique.
Existing and previous data acquisition system for modelling and
measuring human faces does not involve with the integration or
combination of more than one system. Most of the system only
implement one sensor either stereophotogrammetry or 3D laser
scanner. The combination of the two system will enhanced the
accuracy, geometry and visual quality of the craniofacial spatial
data.
Figure 2. Craniofacial Spatial Data Acquisition System -
Physical Design
L2 L1
Figure 3. The location of laser scanner LI and L2
C6 C3
Figure 4. The location of camera C3 and camera C6
Both sensors (stereocameras and 3D laser scanners) were
operated one after another. The stereocamera system was
operated using battery while the scanner was operated via
computer and Polygon Editing Tools (PET) software. The
details information regarding the system is discussed below:
2.2 Stereophotogrammetric System
The objective of having a stereophotogrammetric system in the
prototype system is to acquire high resolution stereo images of
craniofacial morphology. The implementation of the system
followed the basic stereophotogrammetry operation that has
been applied in aerial photo mapping. The developed
stereophotogrammetric system consists of eight high resolution
(8.0 Mega Pixels Sony DSC F828 - as in Figure 5) professional
digital cameras. Six of the cameras were setup in stereo mode
with calculated stereo base distances. The six cameras captured
70% stereo-overlapping images and setup 800mm in-front of
the patient. The last two cameras was setup in convergent mode
to capture two convergent images. The cameras were control
and synchronized using new special built camera lane controller
(as in Figure 6). The user can switch on/off and release the
shutter of the camera easily using the controller. All the cameras
can be accurately synchronized within 0.2 milliseconds. The
stereo and the convergent images of the craniofacial
morphology was stored in the compact flash memory card and
was downloaded into CPU using multi-card reader device for
further processing tasks.
Figure 5. The Sony CyberShot F828 professional digital camera