RECENT DEVELOPMENT OF INDUSTRIAL PHOTOGRAMMETRY IN JAPAN 
MEASUREMENT OF MARINE MODEL PROPELLER 
CAVITATION IN HULL PRESSURE 
Full scale investigations of propeller cavi- 
tation are very important in order to check 
the efficiency of the propeller and to find the 
cause of vibration and cavitation of the pro- 
peller. The thickness of bubbles in the case of 
the cavitation was measured by comparing 
  
Stereopair ot tire. 
341 
the propeller without tank water. The 
SKB-25 stereocamera was used for taking 
photos in combination with a strobe light. 
The propeller at high speed can be photo- 
graphed in coincidence with the high-speed 
strobe light. The coordinates on the plate 
can be transformed by comparing the propel- 
ler coordinates without tank water. The 
mean square error of measurement was + 0.1 
mm. 
PRECISE ANALYTICAL PHOTOGRAMMETRY FOR 
MEASUREMENT OF THE MODEL 
In industrial photogrammetry, precise 
measurement is sometimes important for de- 
sign construction with severe criteria. This is 
combined with the stereo-camera, com- 
parator, and computer and the problems in 
this case are the distribution and number of 
control points. Size and marking of control 
points, geodetic measurement of control 
points, position and direction of the stereo- 
camera and its selection, transformation and 
adjustment of the control points and the 
check of physical condition of camera and 
plates, and especially the mathematical for- 
mulas for checking the control points are the 
key factors for this measurement. The inner 
orientation factors have an important effect 
upon the result. These must be considered in 
synthetic ways. 
The actual measurement for an architec- 
tural model was tried by this analytical means 
using two SMK-120 stereo-cameras which 
were used for photographing from the upper 
side on a specially designed platform. The 
object was the model of a famous temple, 
about eight meters by seven meters in cross 
section and three meters high. The distance 
between cameras and object was eight met- 
ers. The mean square error of measurement 
was about + 0.2 mm in plane coordinate and 
+ 1.5 mm in height. 
CONCLUSION 
Short-range photogrammetric methods 
have played an important role in the field of 
industrial photogrammetry and the results 
have been most satisfactory. But there are 
various problems which must be solved if 
short-range photogrammetry is to be applica- 
ble systematically. Since only a few examples 
have been given, we must perform more re- 
search in order to find integrated techniques 
in considering economical and easily applic- 
able conditions. 
ACKNOWLEDGMENTS 
The author is very indebted to the mem- 
bers of Bridgestone Co. Ltd., Ohbayashi