| OCR Text |
Show have also been taken [5] [6] • The positions of surface points in each photograph have been measured. electromechanical device used to measure surfaces consisted of two potentiometers mounted at a gimble to angular position and a third potentiometer to sense po in a radial direction [7]. Another electromechanical c has used mutually orthogonal linear potentiometer directly sense positions in rectangular coordinates. have been used to gather three-dimensional data. One of wand has used three retractable cords [8]. The po of the wand has been found by determining the poir intersection of three spheres with centers at locations and radii equal to the unretracted lengtr cord. A second type of wand has used a spark ga,p and orthogonal microphones [9]. The position of the wane been established by the distance from the spark gap tc microphone. A third type of wand has used an ultrc signal and four microphones mounted at the corners rectangle [10]. Again, the point of intersection of spheres with known radii and centers at known locatior been found. The fourth microphone has provided a geo check. Data describing imaginary surfaces have been genel Surfaces of regular mathematical objects, approximat polygons, have interpenetrated been [11] • built, scaled, joined, The data used to describE |
