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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
CREST syndrome is one form of scleroderma, a progressive 
disease that leads to hardening and scarring of the skin and 
connective tissues. The acronym CREST stands for the 
manifestations of this syndrome, which are: The "C" stands for 
calcinosis, where calcium deposits form under the skin on the 
fingers or other areas of the body. The “R”, stands for 
Raynaud’s phenomenon, spasm of blood vessels in the fingers 
or toes in response to cold or stress. The "E" represents 
esophageal dysmotility, which can cause difficulty in 
swallowing. The "S" is for sclerodactyly, tightening of the skin 
causing the fingers to bend. Finally, the letter "T" is for 
telangiectasia, dilated vessels on the skin of the fingers, face, 
or inside of the mouth 
Raynaud's is a condition that causes some areas of your body 
— such as your fingers, toes, tip of your nose and your ears — 
to feel numb and cool in response to cold temperatures or 
stress. It's a disorder of the blood vessels that supply blood to 
your skin. During a Raynaud's attack, these arteries narrow, 
limiting blood circulation to affected areas. Spasms of the 
small blood vessels (capillaries) cause color changes varying 
from white to blue to red. Example of this would be when 
fingers become white due to lack of blood flow, then blue as 
vessels dilate to keep blood in tissues, finally red as blood flow 
returns. Exposure to cold or emotional stress can intensify the 
problem and there may be pain, tingling, numbness or a 
burning sensation. 
2.0 MEASUREMENT SYSTEM 
The measurement system itself comprises both software and 
hardware components to allow measurement either in static or 
dynamic modes. The system utilizes dual CCD cameras linked 
and synchronized by computer and software. The system is 
designed to allow for multi-processor, multi disk system that 
will support multiple camera units that are interfaced to a 
custom projection system. The system was designed for real- 
time measurement, but will also work in offline batch 
processing of data. 
The dot projection process excels in areas of dynamic 
measurement especially in areas of human skin and thin skin 
membranes. 
  
Figure 1. Dot pattern projector 
Several combinations of synchronized digital cameras have 
been tested from 1 to 2 mega pixel size although larger pixel 
sizes are available for special applications. The cameras used 
can operate up to 15 and 30 frames per second, higher frame 
rates are also available for specialized applications. (See 
Figure 2 and 3 for example camera systems) 
  
Figure 3. 
2.1 Automated Measurement 
The stereo matching principal used in ShapeCapture and 
ShapeMonitor software is based on epipolar geometry as 
shown in Figure 6. 
  
e 
Z UT 
pl Epipolar plane 
A ae 
ae 
Nd 
tm HN 
T u 
N 
O1 N 
N : 
^ / 
NN y 
> NU 
x Y = 
7 P 
ze 
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t X 
  
Figure 4. Epipolar Model 
The object point P, the two projection centers of the two 
images, Ol and O2, form a plane (the epipolar plane) that 
intersects the two image planes. As a result, two epipolar lines 
are created. The matched points fall on these lines. Once the 
camera positions and orientations at the two image locations 
are known, the equations of the epipolar lines become known. 
We will now start by taking the coordinate pl in the left image 
and look for point p2 on the epipolar line in the right image. 
Since there could be other points falling on the same line, we 
need additional constraint to make sure we select the 
appropriate point. 
The projector can be configured with several dot pattern sizes, 
down to 154 micron spacing. this, along with motorized 
projector movement over the object can provide point cloud 
data equal to laser range data. The system can be configured in