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234 AED-28 75.99 4.11 W 
235 AED-28 85.64 1,21 6.84 
236 AED-28 190.62 -37.66 6.15 
237 AED -28 199.53 58.68 5.95 B 
238 AED-28 178.56 0.76 29.39 
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Tel.+41<22>7328810 Fax+41<22>7410450 
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DIGITAL HAPPING SVSTEMS 
5175501.03 i 
298118.18 
Figure 3. 
The final result of data processing in form of photomap. Raster topography map, laser image and orthorectified photo 
along with main contours and other semantic data are presented. 
1) Full or partial absence of corresponding points on a 
pair photo, that might be caused by complex relief, 
vegetation, buildings, or other factors. The major 
negative result here is malfunction, and sometimes a 
failure of 'above algorithms of automatic stereomodel 
construction. Thus, even in the current digital 
photogrammetry systems these processes require the 
most thorough attention of operator to each stereopair. 
And this very fact results in such a high cost of 
stereophotogrammetric DTM production. 
2) Another principal difficulty is that georeferencing 
error grows up as a frame distance increases from 
primary (geodetic) ground control points, on the above 
mentioned of lack of interior control mechanism for such 
situation in the stereotopograrphy method. This issue is 
less important in area than in corridor survey, and with 
available GPS reference of principal point. 
Nevertheless, this very reason causes loss of stability 
(mostly cross-path) and therefore geopositioning 
accuracy reduction in one of the most practically 
important cases - corridor survey of long linear objects 
(power lines, oil and gas piping etc.) in hard accessible 
areas where such geodetic support is extremely 
complicated (sometimes just impossible). 
So the problem of photos mutual orientation in stereo 
pair is the most difficult thing on the way toward the 
complete automation of steretopographical method. 
Laser locator DTM may play the main role here. 
The main procedures of automatic mutual orientation 
algorithm are presented below. 
1) As a first step the special DTM processing is 
implemented with a goal to recognize the fragments 
which are “favorable” in terms of possibility of 
mentioned above correlation algorithms usage for these 
fragments. It means that such fragments must be 
smooth enough and be free from vegetation, buildings, 
etc. 
2) The aim of the second stage is transfer of selected 
“favorable” fragments (their mathematical images) to 
the coordinate system of each frame taking into account