16 REPORT OF THE INSTITUTE OF INDUSTRIAL SCIENCE, UNIVERSITY OF TOKYO 
were obtained. 
The airplane chartered for this photographing mission carried an Infragon lens besides 
an Aviogon lens. The photographer on September 30 took oblique photos by using infrared 
films from a high altitude approximately 4, 200 meters west of the typhoondevastated area. 
The photo shown as the frontispiece one of the oblique photos taken at that time. 
Since infrared photos possess a characteristic that a watery place comes out black, we 
can distinctly recognize the condition of the entire submerged area which was hit by the flood 
tide. 
Particularly, depending upon the degree of muddiness of water, a great difference was 
observed in the density on the photos, (three rivers empty into the sea) and this enabled us 
to conjecture the time lag of inundation and the conditions of overflowing. Such a difference 
in turbidity did not come out explicitly in panchromatic vertical photos. Thus it was found 
that oblique photos taken by the infrared film were highly effective in grasping the general 
situation existing at the time of the disaster. 
8. CONCLUSION 
Few Japanese have had first-hand experience in the technique of infrared aerial photo- 
graphy and we had to start our research from the most rudimentary stage. However, now 
that full-scale shooting has become possible at long last, we intend to apply infrared photo- 
graphy extensively to practical operations in the future. 
We are convinced that various new avenues of use will be opened up for infrared aerial 
photography. Needless to say, its effectiveness will be multiplied if it is utilized together with 
panchromatic and color photography. 
We intend to use these methods effectively and cultivate photogeology, which is develop- 
ing as a new branch of science.