tion is equivalent with stereoscopic point transfer. The final results 
of the block adjustment refer to the hardware system used. They include 
in particular all instrumental errors of the analytical plotter and the 
digital equipment. 
It may be remarked that transfer points in this system are identified 
and recorded by their image coordinates alone. In connection with ana- 
lytical plotters, transfer points need not be marked as they are pre- 
cisely identified and can always be recovered later through their image 
coordinates, after restoration of the interior orientation. 
The tests refer to black and white wide-angle photography from a recent 
cadastral project (Schnürpflingen) and an older test block (Appen- 
weier). They contain signalized points which were also measured for 
comparison purposes. However, the digital point transfer refers to ar- 
bitrary non-signalized terrain points, as they might be used for con- 
ventional transfer and marking of tie points. 
Digital point transfer for aerial triangulation is in fact a multi- 
correlation problem. It can be shown, however, that the problem can be 
handled in separate steps by transferring one chosen point step by step 
into all other photographs in which it occurs. 
Both tests refer to large scale photography (1 : 4000 and 1 : 7800). 
Nevertheless, the precision results are representative for small scale 
photography, too /4/. 
2. TEST BLOCK SCHNÜRPFLINGEN /5/ 
2.1 For the first test photography of the cadastral project "Schnürpf- 
lingen" was used. The pertinent data are: photoscale 1 : 4 000, camera 
Zeiss RMK A 15/23 (wide angle, flown with forward motion compensation, 
exposure time 1/100 sec., Kodak Panatomic X film, 14 DIN, black and 
white), forward overlap 60 %, side overlap nominally 60 % (actually 40 
- 80 %), flight mission on April 5, 1985. The original film negatives 
were used. 
The investigation was made with a subblock of 4 strips with altogether 
26 photographs, i. e. 4 strips with 6 or 7 photographs each. Because of 
irregular flight lines the intended side overlap of 60 * was not every- 
where reached. Some photographs show considerable angular image motion, 
in connection with the long exposure time. Each photograph contained 
about 16 signalized points. For the block adjustment 12 signalized 
Xyz-control points were used, distributed along the perimeter with 
average spacing of 2 base lengths. The assessment of the final accuracy 
is based on 107 signalized check points which were not used as control 
points nor as tie points in the block adjustment. 
2.2 For comparison purposes the block was measured 4 times, see 
table 1. 
a) At first all signalized points were measured with the Zeiss mono- 
comparator PK1, in order to assess the best possible result 
obtainable with the material. 
b) Then all signalized points were measured with the analytical plotter 
Zeiss Planicomp C 100, in the monocomparator mode. These measure- 
ments represent the reference for the comparison intended here. 
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