WORKING GROUP 4 
DOVERSPIKE-HELLER 
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recycle as fast as 8 frames a second and has a fast rotary shutter capable of 
speeds up to 1/7200th second. 
The films used were Super Anscochrome with an ASA rating of 125 for color 
and Plus X Aerographic with an ASA rating of 80 for the black and white 
photographs. 
Photographic scales used were 1 : 3960, 1 : 1584, and 1 : 1188. These scales 
correspond to area units of measurement commonly used in the United States. 
White panels were placed on the ground to aid identification of each location 
from the air. 
The film was developed locally so that reflights could be made if necessary. 
Glossy contact prints were made with as nearly equal an amount of tone and 
contrast as possible. 
Office procedures and photo interpretation 
Cellulose acetate overlays were prepared showing the location and number 
of each tree on each film and scale combination. 
It was decided to determine whether morphological features such as crown 
apices, crown margins, foliage arrangement, and foliage density would help 
increase interpreter accuracy. Five experienced photo interpreters examined 
sample trees to define the above characteristics and write specifications as to 
how these trees looked on aerial photographs. This review of sample trees 
served to train the four experienced photo interpreters and the one recent 
graduate from a forestry school who were used in the test. Botanical terms and 
drawings were used to describe the morphological characteristics of the trees. 
A Munsell gray scale was used on the panchromatic prints to correlate tone 
with species. 
An innovation in the interpretation of color film was made by tying in color 
represented on the transparencies with Munsell standard color chips. These 
standards represent spaced division of the three attributes of color known as 
hue, value, and chroma. The color chips were remounted on special cards with 
prepunched holes to facilitate matching the colors. This type of mounting has 
been done previously for soil sampling. The color matching was done to see if 
the human eye can associate tree species by any one or all of the attributes 
of color. 
The panchromatic photographs were examined with a 2^2 power pocket 
stereoscope under reflected light, and the color transparencies with a 2*/2 power 
stereoscope over a specially built light table. 
The panchromatic photographs were interpreted first, starting with the 
smallest scale and proceeding to the largest. 
Uniform lighting conditions and the same interpretation equipment were 
used by all interpreters. Two interpreters recorded this data on tape recorders 
and transferred it to the tally forms later. This was found to be much more 
efficient since it was faster and less tiring for the interpreters. 
All interpretation data were coded and put on specially designed forms 
before being transferred to I.B.M. punch cards for tabulation and analysis.