carried out in the same mode that 
measuring of fiducial marks. Having 
accomplished the stereo viewing and 
recording measured coordinates of 
homologous points on photos, the 
software package automaticly drives 
floating mark to the centre of the next 
zone. 
In such a succession coordinates of all the 
tie points of stereo pair will be measured. 
It is necessery to say that using a driving 
of floating mark with manual steering- 
wheels it is possible to add into 
measurment points that situate free on 
stereo pair presented in the project. 
2.3. Digital point transfer for forward 
overlap 
Digital point transfer for forward owerlap in 
the new technology realizes by the 
following method. On the first stereo pair 
an operator searches and records 
coordinates of tie and common points at 
zones selected during project designing. 
On the second and following stereopairs 
an automatic reaching of floating mark to 
tie points on one of the photos is realized; 
after that an operator gets possibility to do 
stereoviewing by moving only the second 
photo. An error of coordinates point 
transfer is mainly defined by errors of 
fiducial marks viewing by the 
STEREOANAGRAPH analytical plotter and 
its instrumental precision (with the results 
of carried out research these precision is 3 
mkm). 
There are two independent methods of a 
quality checking of  photogrammetric 
bridging: 
- by the results of relative orientation of a 
stereopair; errors of vertical parallaxes 
are calculated (this method needs not less 
than 6 points); 
440 
- by the coordinate differences of the 
homologous points got from two 
neighbouring stereopairs (it is necessery 
to have not less than 3 tie points). 
Photogrammetric bridging always begins 
with the upper strip using a data project. 
The AP software for aerotriangulation in 
dialoge mode drives to an operator to do 
laying down of photos N 1 and N 2 and 
switching over of viewing axis of the 
analytical plotter. 
The last one is necessery for realization of 
a method which shortens time for photos 
relaying. Process of strip net modelling is 
a cyclic repeatition of process of single 
stereopair modelling, presented earlier, 
until the last stereopair of a strip will be 
processed. As a result of this process the 
common model is formed, it has free 
scape and orientation relatively of geodetic 
coordinat system. 
If there is essential quantity of control 
points for strip network, it is possible to use 
preliminary adjustment with checking of 
vertical and horizontal coordinate 
differences of control points. But for block 
adjustment, when rarefied control, the 
main part of a strip nets has not essential 
geodetic points. That is why checking of 
the net on this part is admissible value of 
errors on intermodel of tie points and 
vertical parallaxes. 
In case of excess of admissible mean of 
errors the defective points have been 
eliminated or remeasured. It is important 
to measure tie points, participating in block 
adjustment and fiducial marks, defining 
accuracy of the method of digital point 
transfer especially thoroughly. 
Results data with measurings of a strip are 
entered to the STRIP file. Measuring of 
coordinates on the next strip are carried 
out only after getting to it tie poins from a 
previous strip. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996 
m a3 
- TS m 
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0) CI CY 3: "73