Alstat * Vstat ^ ^pc (hy + oF x)
Here AZ is the observed statoscope reading, converted to me-
tric units, hg and ao stand for the unknown initial height of
the isobaric surface and its tilt along the flight line, res-
pectively. Those observation equations tie in with the photo-
grammetric block-adjustment via the common unknown heights
Zpc of the camera stations. The observation equations for APR
recordings are of the same type, referring to the heights Zi
of terrain points instead of air stations.
The observation equations must be weighted in relation to the
photogrammetric measuring precision, i.e. to the weight unit
chosen. The combined least squares solution is quite straight
forward, complicating the standard photogrammetric block-
adjustment very little. The solution not only assesses per
flightline the additional unknowns hg and a, it also estima-
tes the residual errors v of statoscope or APR measurements,
thus allowing precision estimates and recognition of out-
liers. The method has not only the advantages of a least
squares solution and allows great flexibility of application.
Its main success is the drastic reduction of vertical ground
control. With statoscope or APR practically any feasible
distance can be bridged between vertical ground control,
still meeting all requirements of contouring for small scale
and medium scale topographic mapping. Both theoretical stu-
dies and experimental tests have confirmed that vertical
control is only required in most cases at both ends of a
block and can still further be reduced if cross strips are
applied /6/. It has been shown that vertical control can even
be carried in from outside the area with APR, allowing the
adjustment of blocks without direct vertical control /7/.
Some tests have shown that the method is most successful
even in large scale mapping, for contour intervals of 5 m or
2 monly, /8/7.
Regrettably the application of statoscope in aerial triangu-
lation is not as widespread as it would deserve. Its appli-
cation is most economic, and it is, perhaps, the instrument
with the highest cost benefit ratio known in photogrammetry.
A limited number of organisations are applying it, however,
with great economic success.
3. NEM NAVIGATION SYSTEMS
3.1 Very recently new navigation systems for air survey
flight navigation have emerged or are emerging which create
a new situation with regard to camera orientation. All
systems in question are actually intended for flight navi-
gation purposes. We may expect, however, that their data can
also be used successfully as additional orientation data
for combined block-adjustment in the same way as it was des-
cribed above for statoscope data. There are 3 types of navi-
gation systems which are of interest:
