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DESCRIPTION OF THE EXPERIMENTAL-MEASUREMENT SYSTEM — As shown, Figure 10 illustrates the 
interfaced video camera-sampling processor-computer-TV monitor-meters-tape recorder-keyboard com- 
ponents of the real-time video photogrammetry system. The camera is mounted on a four degree of 
freedom mount [three translational, one rotational (yaw)|, at one end of a 4.2 meter precision track. 
To provide high stiffness to the support of a target carriage mounted on the track (and its motor 
mounted targets), the track itself is two one inch (25 mm) diameter machined rods, with a lateral 
spacing of approximately three feet (1 m) which were precisely aligned to be level and parallel to each 
other. A target carriage mounted on these rails, by means of four ball bearing guides at the corners of 
the carriage platform, can be moved along the track by means of an electric motor-pulley-cable drive. 
On the horizontal platform of this target carriage, different targetted object systems can be 
mounted; for example, as shown in Figure 11, a calibration target board having a 5 x 5 array of white 
targets with black background and manually adjustable yaw and pitch angles within its supporting 
frame or, as shown in Figure 12, a motor powered target system (black targets on white) providing 
roll and lateral coupled motion. 
As now developed, a two directional joy-stick proportional control (shown in Figure 12 
below the TV monitor) permits an operator to control simultaneously the motion along the track 
and the roll motion of the motor powered target. It might be noted at this point that to the left of 
the TV monitor in Figure 12 is the laboratory prototype of the video sampling processor. 
The position of the carriage along the track is measured by means of a pointer on the target 
carriage and a steel measuring tape fixed to the track (mm divisions). For convenience of the operator, 
the position of the carriage along the track is also measured by means of a precision ten-turn potentio- 
meter attached to the pulley drive system (not shown in Figure 10) whose output voltage, as displayed 
on a digital voltmeter, is adjusted by means of suitable circuit components to correspond to the tape 
reading (viz. 2.000 volts = 2.000 m). 
When the photogrammetrically derived values for position and orientation (and velocities) 
are brought out of the computer by means of digital to analogue converters (DAC's) and the voltage 
displayed on similar voltmeters, the photogrammetrically derived distance can be directly compared 
with the track potentiometer derived value, as the target carriage is moved along the track by means 
of joy stick control. By this means operator control of the position and speed of the targetted object 
by the on-line 30 Hz real-time single video camera photogrammetry system can be demonstrated. 
To carry out experiments and demonstrations with the special illumination-target system, 
the small LpNa source and beam splitter is attached to the same base plate as the camera and the 
filter may be put in or taken out of a fixture immediately in front of the lens, as shown in Figure 13. 
A target board with a white background and four sheet multi-cube corner targets, which was used 
during development testing, is shown in Figure 14 (as clipped onto the front of the calibration target 
board). The removable pegs are used to cast shadows with oblique lighting to show, and evaluate 
their elimination by the filter. 
These targets, one inch (25 mm) diameter, are located at the corners of an eight inch 
(0.203 m) square. For more precise measurements, the white painted discs, inserted into recesses 
behind the precision machined holes of the calibrated board target (Figure 11) would be replaced 
with discs faced with the sheet cube-corner material. 
In considering the illumination engineering aspects for target-background contrast, it should 
be noted that the paints used for the target systems are neutral density with a constant luminance factor 
over a large range of illumination-view geometries as determined for their use in the night visibility 
studies). O), 
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