Carl
Scope
view
. The
k has
lator
image
desk
tions
ished
EREO-
nical
d the
ussed
ed to
This
tape
pe is
atter
ation
rans-
mpute
ware.
wl, (02 are required as parameters for this coordinate trans-
formation. Except for the camera focal length which is generally
known, all these parameters can be determined directly on the
air photos, provided that the terrain coordinates of at least
three control points are known. These parameters are computed
with the aid of the orientation programs which are an essential
component of the software.
3. Uses o f the Stereocordàá4
Viewing the two photographs through the stereoscope, the
operator sees a three-dimensional model of the terrain together
with a floating mark which can be placed on any desired point
within the stereo model (figure 2). The desk calculator then
computes the terrain coordinates of the point on which the
floating mark has been placed. The machine thus primarily serves
to determine the coordinates of individual points. However, if
several points are set in direct succession, other quantities
can likewise be measured with the aid of suitable computer
programs. These are:
Horizontal distances and distances in space.
Level differences (for instance, height of buildings or trees).
Slope angles (for instance, of hillsides).
Azimuth angles (for instance, of geological features).
Dip and strike angles of geological strata (provided that
the stratum is visible at a minimum of three points).
Planimetric and surface areas.
Volume (for instance, of cut and fill, projected dams etc.).
p ! STEREOSCOPE
AERIAL = Ea
|
PHOTOGRAPHS
STEREO MODEL
SURFACE
AREA VOLUME
DIP & STRIKE ANGLE
OTS)
XN
A AR
AZIMUTH ANGLE ; 2
A - Ss
SPATIAL N |
DISTANCE AM
eei "i
'
SLOPE ANGLE
VERTICAL
DISTANCE
Fig.2: Measuring
from a stereo model