on type A,
200 um
els.
- 500 um e
o
5 -
It appeared however, that the deformation reconstructed in
this way is much smalier than the original model deformation.
This can also be proved within the theory of least squares
adjustment. Reasonably good results are only obtained with
dense control in the strip or block.
The most appropriate method is of course to examine the
theoretical and the estimated factual n-dimensional distribution
function of the residuals after least squares adjustment. Using
the differences in size and shape between these distribution
functions it can be checked whether the original assumptions
regarding the error properties of the image or the model
coordinates hold. Both methods described above are partial
methods within this general class of tests.
The elimination of the effects:
Beside the problem of detection there is the even more important
problem of compensation. The ultimate aim in practice is of
course not only the location, but also the elimination of the
effects of systematic image errors. These two problems of
detection and elimination are strongly interrelated, as an
elimination pf error effects seems only justified if significant
effects are detected.
A,very general and elegant method of computation is to extend
the mathematical model of the projective relationships and to
include also terms for systematic image errors (cf. Schmidt
1971, Masson d'Autume 1966, Cenan 1970).
These extended projective relationships are then as follows:
a, (X-XS)+a,(Y-YS)+az(Z-25)
€ > a i J
V_+X-X, = C $+ £0 (2) (g~Y-)
x 0 a (X-XS)+ag(Y-YS)+ag(Z-ZS) ij 1j' ^9 0
a, (X-XS)+a (Y-YS)+a, (Z-Z5) i
V1-39 = oA 2 + 1554 4(X-X9) (y-yg)?
a, (X-XS)*ag( Y- YS) «ag( 2-28)
e / A iy
conventional formulae extension for
systematic image
errors
(X, Y, 2) coordinates of a terrain point in an arbitrary
rectangular terrain system