- To consider correlations between the observations better 
or generally speaking to obtain more rigorous stochastic 
modelling. 
- To increase or optimize precision, reliability and econ- 
omy by having more flexibility in an integrated planning 
of all measurements. 
1.2. Data from navigation systems, satellite surveying or 
other sources 
With satellite or inertial surveying systems positions of 
ground points are determined, which can be used as control 
points, assuming proper mathematical modelling. 
For aerial triangulation it seems to be of very considera- 
ble importance that more and more precise navigation in- 
struments provide information about the position or orien- 
tation of the aircraft or the sensor (Ackermann /1/). 
A review of navigation and sensor orientation systems is 
given by Corten /4/. 
The planimetric position of the camera or sensor can be 
determined e.g. by distance measurements to given ground 
positions. Statoscopes measure altitude differences re- 
ferring to an unknown isobaric surface. For positioning in 
space the use of the satellite system NAVSTAR/GPS is very 
promising. Orientation angles can be determined by laser 
gyros and for the derivation of the complete position and 
attitude of the camera inertial surveying systems (ISS) 
can be used. Integrated or hybrid systems consist of more 
components, either to improve the weak points of a single 
sensor or to improve reliability. Typical examples are 
Doppler/ISS, GPS/ISS or Loran C/ISS hybrids. 
The application of navigation data may get a strong impact 
on aerial triangulation at least in small scales. 
l9. Object information 
In the point determination process any given geometric 
object information that can improve the results should be 
included, i.e. forms or figures found in the object like 
points on lake surfaces, straight lines or planes should 
be introduced into the adjustment procedure. 
Further information could be taken from existing local or 
global digital terrain models (DTM), i.e. discrete ap- 
proximations of the terrain surface. Investigations with 
real and simulated data are performed at the Chair of 
Photogrammetry, Munich on the use of these data in the 
photogrammetric block adjustment. Various simulations 
based on three line imagery are given by Ebner, Müller 
/7/. The studies, concerning the mathematical formulation 
and the effects of introducing this DTM information on the 
quality of point determination, show very promising 
results for certain applications. 
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