Abstract:
The development of personal computer software
coupled to an analytical stereoplotter allows major gains
in efficiency and accuracy in a number of forestry related
subjects. This thesis describes the operation of a system
developed by Carto Instruments.
This thesis demonstrates how area estimates might be
made in a systematic way within 5% of true values by
accounting for topographic displacement, non-horizontal
flight, and imprecise determination of scale, factors that
conventionally result in errors of more than 25%. Ground
distances were accurate within 3% at 300 feet on 1:31000
scale black and white prints. At a similar scale, tree
heights ranging from 40 to 100 feet could be consistently
estimated within 10% of true height.
When applied to mapping the location of snags, key
features of riparian zones, and changes in canopy
openings, the system proved satisfactory on various filni
media and scales. Historical analysis of aerial
photographs was demonstrated by adjusting to common scale
and measuring rates of vegetation change over four decades
toward canopy closure. The same approach has application
for other historical analysis where aerial photographs are
available.
The application of the system to terrestrial
photogrammetry was demonstrated using 35 mm transparencies
to measure tree taper within an accuracy of 2 inches.
In summary, merging of software written for a
personal computer has finally made the benefits of
analytical stereoplotting economically available to a host
of forestry-related topics and provides an opportunity for
numerous applications including, as demonstrated, a more
accurate digitizing of data to be included in any
geographic information system.
