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averaged about 1:2700 being flown about 820 m above the ground. The scale of the
models was controlled by the radar altimeter and by ground control at the ends of the
1 km transect. Model restitution was further aided by data from a tip and tilt indicator.
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PHOTO NUMBER
| | TREE CANOPY PROFILE
GROUND PROFILE
FIGURE 2. Copy of original output of radar ground and tree canopy profiles.
The tree profile is offset to the left by one division.
The profiles were drawn by plotting from independent stereo pairs mounted
on a Zeiss Stereocord plotter (Figure 5). The Stereocord enables the profile to be
digitized (x, y and px) and fed to a programmable calculator which carries out the model
restitution and drives an xy graphic plotter. The graphic plotter coordinates were scaled
to match the radar strip chart record counterpart. The photo profile was built up by
joining adjacent models through photo control points. The forest canopy profile could
then be plotted along the flight path of the corresponding radar altimeter flight; the
ground profile was plotted wherever the ground or ground vegetation could be seen on or
near the flight path just mentioned. The dotted and dashed lines in Figure 6 are
respectively, the photogrametrically generated terrain and forest profiles. The broken
and solid lines were copied from the strip chart record of the radar altimeter and
represent the terrain and forest canopy respectively. This profile covers the same line as
the profile in Figure 3, however, the vertical scale is different.
Species identification was treated as a secondary objective and thus was
restricted in scope. Constraints were imposed both by the amount of time available for
collecting species data on the ground and limited access to existing data. A second
limitation was imposed by the photo interpreters having no experience or knowledge
related to tropical tree species. Nevertheless, the good-quality, large-scale photos taken