Vegetation of Southeast Asia Studies of Forest Types 1963-1965

It was decided to determine whether morphological features, such
as crown apexes and crown margins, which may be associated with tree
form and growth, would help increase interpreter accuracy. The foliage
density was classified as thin (less than 25 percent), medium
(26 to 75 percent), and dense (more than 75 percent). A set of terma
was devised to relate the foliage arrangement of the species being
considered to the shape of the images found on the large-scale aerial
photographs. The interpreters examined sample trees to define these
foliage and branching characteristics and to write specifications
as to how each species looked on aerial photographs. A Munsell gray
scale was used on the panchromatic prints to correlate tone with each
species.
The panchromatic photographs were examined with a 2.25 power
stereoscope mounted on a specially built light table. All interpretation
data were coded and put on specially designed forms before
being transferred to IBM punchoards for tabulation and analysis.
The investigators found that interpretations of color transparencies
were more accurate than those of black and white prints.
There was a highly significant difference between the two films. Also,
accuracy of interpretation was poorer with the small scale than with
the two larger scales. Differences in interpretation were highly
significant between all scales on panchromatic film. For the color
transparencies, the two larger scales were almost equally accurate,
and both were significantly better than the 1:39^0 scale.
The authors came to the conclusion that color film is superior
to panchromatic film for use in identifying individual tree species,
This may be ascribed in part to the fact that people are accustomed
to seeing and identifying objects not only by shape and form but
also by the color. A ripe tomato is distinguished from the vine by
its color rather than its shape, and cotton can be graded by the degree
of lightness and yellowness of the fiber. A forester trained
to recognize trees by certain features also has an associated color
for that tree in his mind. When he is trained to recognize the tree
on aerial color photographs, he is equipped with one more dimension
with which he is familiar. Thus, it requires more training for an
interpreter to be able to recognize objects by tones of gray than
by the normal colors with which he associated the object. In panchromatic
interpretation he must learn to relate the tone of the
image to color, and by associating its form and texture he can
identify the object.
Tree species were identified accurately enough on the large
scales of color film to suggest the possibility of using them on
actual inventory problems. Further study of hardwoods, especially to
associate their crown and foliage characteristics with age and physiographic
features, should be helpful in improving identification
of these tree species.
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