- (D
(389)
In the overlap of two adjacent models, the A z must then satisfy the relation
b b
T Az (A br — 4A br) + [2€ + 7 bf
and for the points N (y — 0), A (y/z) — d- t, A (9/2) = —t
the relations
[Sanct an lolo t Yon
z À za — zZ Az )=e et zz 7 tbf
Z
[pues vint nites
zZ AZN— 7 52A ze NL "Jb
N
must be satisfied with the limits of precision, in one case in the relative orien-
tation procedure and in another case in the measurements of elevations. An error
in one of the three is thus easily detected, indicating a y-distortion anomalie of
the perspective rays of the corresponding point.
One can perform the solutions graphically by plotting as abscissas the
quantities
(b/za — b/z . x) and [oan >, )
and as ordinates the values of the function b A z/z the points must lie on a line
of slope e, whose y-intercept is t bf.
In the case of fairly level terrain the systematic error e is not erratic and
one must have
A za — À 2y # À Zn — À Za = y B
the operation of using ground control is simplified.
It is thus possible to eliminate an important cause of observed breaks in
stereo triangulation.
METHOD OF PHOTOGRAMMETRIC STEREO TRIANGULATION
by
George Poivilliers.
Abstract. The systematic errors are made as constant as possible by keeping
the air base at a fixed length. The errors caused from local distortion anomalies
of the perspective rays are eliminated. The operations are reduced to a single
adjustment.
Photogrammetric stereo triangulation consists of attaching successive models
where the scale and orientation are adjusted to fit the preceding model. The first
and last models of the chain are adjusted to points of known ground position. In
the *cantilever extension" only the first model rests on known control points.
In this chain there is an accumulation of errors, a failure of the orientation
and scale of one model is reflected in all the models that follow.
These failures in the orientation and in the scale of the models and their
deformations can have an accidental character, such are those indicated by the
