Hakodate 1998 
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ised in the 
Figure 1 
The Black-and-white CCD camera is appropriate 
for the low illuminance environment and low price 
According to the actual size [BOmmx80mm-30mm] of 
the object space control frame, the space resolution 
power fitting in every pixel is +0.16mm , RMS in 
object space is assumed to be +0.3mm, so it is not 
necessary to consider mechanical errors of the CCD 
camera, but only lens distortions. 
The light source with infrared ray near the main 
optical axis is used in order to form sub-binary 
image and work under the condition of normal 
illuminance indoors . The light source with infrared 
ray made by ourselves consists of 56 infrared ray 
diodes. The power distribution of diodes is from 1.5 
to 3.5 mw. The total power the light source attains is 
110 mw, and the direct current voltage is 10 V. 
The tiny control frame consists of 12mm thick 
square made of cast iron and several bolts of 
different lengths affixed on it. Fifteen RRT of 1mm 
diameter are pasted on the top of those bolts and 
the surface of cast iron. By using the two surveying 
piers which locate in the close-range 
photogrammetric laboratory of WTUSM and the 
Topcon-GTS-6 Total Station connected to cornputer, 
the 3-D space coordinates of control points on the 
tiny control frame are solved with forward 
intersection and their accuracy reaches t0.1mm. 
The tiny spinning platform is actually the 
sample platform of an optical microscope with a 
diameter of 12 cm. The tiny control frame can be 
conveniently put on the glass sample platform of the 
microscope . 
The 386/DX computer supplied with multimedia 
video Blaster could be connected with 3 CCD 
cameras. 
3. Digital Close-Range 
Photogrammetric Processing 
3.1 Image acquisition 
Images are recorded by the following steps: 
* A bone with 30~40 quadrilateral RRT , the size 
of which is 0.2mm,is put inside the tiny control 
frame system. 
* The relative position between the CCD 
camera and the control system is adjusted in order 
to get the clearest and maximum size picture of the 
control system on the screen. 
The photographic distance is about 0.7m. 
. 3.2 Image processing 
Attention should be paid to select grey 
threshold in the image processing in order to form a 
high quality sub-binary image on the screen. 
3.3 Determination of space coordinates of 
RRT on surface of hand bone 
Space coordinates of the RRT on the surface of 
the hand bone are solved according to the DLT 
method: 
  
tA Vota L;X+L2Y+L3Z+L4 20 
LoX* LioY tL 41Z 1 
gray na. LsX+L6Y+L7Z+L8 y 6 
LoX* LioY tL 44Z * 1 
where: 
x, y —— pixel number of image point on the 
screen coordinate system; 
^ X, ^ y —— correctness for optical distortion; 
X, Y, Z ——- object space coordinates of RRT in 
tiny control coordinate system; 
{Lo ABS... L141) —— coefficients of interior and 
exterior elements of image and ds , d/. 
and: 
ds coefficient of non-equal scale along axis 
of x and y; 
d/i coefficient of non-perpendicularity 
between axis of x and y: 
The reasons why DLT is adopted in the research 
are : 
x The complex procedure of calibration of the 
CCD camera could be omitted under middle and low 
accuracy; 
4 DLT fits the calibration of the CCD camera, 
spaces of pixels along x and y of which are not 
equal. 
In order to measure the number of pixels of 
image points by using the mouse, the programme 
used has following abilities: 
x Two convergent images can be displayed on 
the left and right parts of screen so the 
correspounding image points could be identified 
and measured easily; 
x Measured point image can be enlarged on 
the corner of the screen so that it is easy to improve 
measuring accuracy. 
x Measured point position can be marked with 
a red symbol right away. 
According to the experiment, the total 
procedure for taking a pair of images and 
photogrammetric  proccesing uses about ten 
minutes . 
4. The Determination of The Degree of 
Coincidence Between Two Contact Surfaces 
of Two Hand Bones 
4.1 The degree of coincidence between 
contact surfaces of hand bones is 
determined according to the following ideas: 
A. The surface of the hand bone is presumed to 
be a quadratic surface with a centre; 
B. The coefficient of the quadratic equation is 
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