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REPORT OF COMMISSION VII 21
interpreter wishes to describe. Ten such terms are defined below and are graphi-
cally presented (Figure 16) as a shape scale, or portion thereof. One possible
use of these terms by the photo-interpreter, namely that of describing the
characteristic shapes of shadows cast by various species of trees is shown in
in describing the shapes of a host of
other objects ranging from ship hulls to
aircraft wings, from landforms to forti-
fications, and from macromolecules (as
interpreted on electron miscroscope
photography) to galaxies and plane-
tary orbits (as interpreted on astro-
nomic telescope photography).
Linear—more than 4 times as long as
wide, with nearly parallel sides.
Lanceolate—about 4 times as long as
wide, and broadest below or about
the middle; lance-shaped.
Oblong—about 3 times as long as
wide, with nearly parallel sides.
Elliptical—about 2 times as long as
wide, and having an outline like an
ellipse.
Orbiculate—less than 2 times as long
as wide, roughly circular or round
in outline.
Spatulate—gradually narrowed from a
rounded summit.
Ovate—having an outline like the
longitudinal section of a hen's egg,
and broadest near the base.
Obovate—inversely ovate, i.e. having
an outline like the longitudinal
section of a hen's egg, and broadest
near the apex ("Ob" is a Latin
prefix signifying inversion).
Oblanceolate—inversely lanceolate; i.e. Fic. 17. An example of the applicability of
about 4 times as long as wide, and terms appearing in Fig. 16 to the problem of de-
broadest near the apex. scribing the shapes of tree crown shadows as seen
Obcordate—inversely ^ cordate; i.e. on vertical aerial photographs.
heart shaped, with the two rounded
lobes and sinus at the apex.
(7) Other Scales. In estimating the steepness of slopes, the heights of objects
or the effects of sun angle on shadow characteristics, still other scales may prove
helpful to the photo-interpreter. Scales of the above types are currently in the
process of development and the results of tests conducted to date are very prom-
ising.
E. TECHNIQUES OF PHOTO-INTERPRETATION:
The general techniques employed by photo-interpreters have been ade-
quately covered in a number of textbooks, including those of Eardley (1942),
Smith (1943), and Spurr (1948). Certain special techniques are described in
parts II to V of this report and in Chapter 12 of the revised MANUAL or PHOTO-
GRAMMETRY (1952). The techniques peculiar to certain types of photo-interpreta-
tion will be covered in papers to be presented by Commission Vii at the
