PHOTOGRAMMETRIC ENGINEERING 
TABLE 1 
DosAGE EFFECT 
  
Tots! Continuous Exposure for Series 
Dose in 24 Hour After 
Roentgens Ours Effect 
0-75 0% Sick None 
100 29% Sick None 
200 509% Sick, nausea in 24 hrs. None 
300 1009, Sick, nausea in 4 hrs. 
249, Die, death in 2-4 
weeks Some 
650 10095 Sick, nausea at once 
95% Die, death in one week Some 
  
Since almost all materials have some shielding 
effect, it becomes necessary to locate all ob- 
jects, in their proper relationships, to each in- 
dividual survivor—in order to calculate the 
actual radiation dose received by each sur- 
vivor of the explosion. With accurate determi- 
nation of individual survivor dosages, corre- 
lations can be made with medical data which 
had been collected by the Atomic Bomb Cas- 
ualty Commission (ABCC). This agency had 
accumulated a large amount of medical data 
concerning individual survivors of the Hiro- 
shima and Nagasaki explosions. These med- 
ical data combined with the new techniques 
of dosimetry developed by the Oak Ridge Na- 
tional Laboratory (ORNL) would make pos- 
sible accurate dose evaluation for many of the 
survivors—if the survivors could be accurately 
located with reference to the point of explosion 
so that shielding effects could be measured.: 
AERIAL PHOTOGRAPHY UsED 
Normally, health physicists concern them- 
selves with such dosage and shielding prob- 
lems. However, in the case of the Hiroshima 
and Nagasaki explosions, certain unique 
problems arose when attempts were made to 
measure the absorbed doses of fast neutron 
and gamma radiation. The density of struc- 
tures in a Japanese urban agglomeration 
posed one difficulty in providing an accurate 
representation of the area of the bombing 
This had to be surmounted to allow correct 
measurements of the angular distribution of 
the radiation and measurement of shielding 
absorption.? At the same time, the representa- 
1G. S. Hurst et al, Rev. Sci. Instr., Vol. 27 
(1956), pp. 153-156. 
? For a complete treatment of the problem of 
tion of the bombed area had to provide ade- 
quate information to facilitate placement of 
each of the survivors in relationship to sur- 
rounding objects and structures. It was felt 
that large-scale maps of the region might offer 
a basic representation from which the neces- 
sary information could be analyzed. The in- 
formation needed was as follows: structure 
densities, street patterns and measurements, 
height of buildings, contour representation, 
floor space measurements, slope of roof cover, 
and placement and heights of miscellaneous 
objects.? 
However, with the total destruction that 
accompanied the nuclear explosion, all of the 
official Japanese maps of the cities, survey 
records, official city planning charts and dia- 
grams, and street plans were destroyed. Lack- 
ing these kinds of records, the project direc- 
tors (ORNL) attempted to reconstruct large- 
scale maps of the neighborhood areas where 
survivor clusters had occurred. These at- 
tempts included survivor interviews, survivor 
sketch maps of their city blocks, interviews 
with neighborhood committees, and field ob- 
servations. None of these efforts produced 
sufficiently accurate and detailed information 
concerning placement of structures, material 
objects, and survivors; nor did they provide 
accurate dimensions and spatial relationships 
of known objects. In a final attempt to resolve 
their problem, members of the Health Phys- 
ics Division of ORNL contacted the Human 
Resources Research Institute (HRRI), an in- 
ter-disciplinary government research agency. 
As a result of this inquiry the matter was 
brought to the attention of geographers as- 
signed to the HRRI staff. This group consid- 
ered aerial photographic interpretation to be 
the most feasible means of providing the 
needed maps. A study was initiated consist- 
ing of the following phases: 
1. Determine the availability of adequate 
pre-strike and post-strike photographs. 
2. Collect materials for horizontal and ver- 
tical information to control compilation. 
3. Establish compilation procedures for 
  
angular distribution of radiation see: ''Health 
Physics Division Annual Progress Report for 
Period Ending July 31, 1957,” pp. 89-91; issued 
November 11, 1957 (ORNL 2384). 
3 There were many other considerations such as: 
burst height, location of ground zero, weather 
conditions, etc., which were necessary. However, 
most of these items were easily obtainable from 
records available to the project investigators. In 
addition, most of these items were not concerned 
with the large-scale map needs of those areas of 
survivor clusters scattered throughout the cities. 
19 
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