polyethylene, a thin coating of white 
opaque, water soluble solution was applied 
to the surface being photographed. The 
thickness of the coating after drying was 
uniform, and did not exceed 8pm. When the 
textured pattern was focused on the compo- 
nent, the concave shape was quite evident 
to both the human eye and the camera lens. 
Using the K-460 camera, a pair of stereo- 
metric photographs was taken of the compo- 
nent when it was new, and after each stage 
of wear. A set of positives made from a 
stereo pair is shown in Figure 6. 
After processing, the film negatives were 
placed in a special Kelsh K-480 stereo- 
plotter for restitution. A photograph of 
a Kelsh K-480 plotter is shown in Figure 7. 
For the tibial prosthesis restitution, 
special lenses and Common Z elevating 
frames were used for an 11.5X plotter mag- 
nification. When combined with the image 
reduction by the camera of 0.61X, the real 
world magnification of the stereo model was 
7X. Therefore, the plotter operator was 
able to orient the model so that the 88.9mm 
(3.500") distance between the two control 
points on the aluminum block measured 
622.3mm (24.500") in the stereo model. 
  
Figure 6 — The stereo pair of the poly- 
ethylene component showing the textured 
pattern from the projector. 
(A tooth was 
photographed on the saddle at the same time.) 
38