International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
Multi scale solutions contribute to this goal by undoubtedly
increasing the overall efficiency and decreasing the necessary
computational time per image. The large number of points,
which may be observed and included in the adjustment
contribute to (a) the reliable computation of additional
parameters for the compensation of systematic errors, (b) the
accuracy improvement for the determination of the exterior
orientation parameters and finally (c) the increase of the error
analysis reliability and, hence, of the overall block adjustment.
However, drastic scale differences pose severe problems to the
automatic solution leading to non convergence. This may be
overcome by suitably instructing the algorithm to compensate
for this effect.
actes WE GE
Visum cua obe EC ege s Ld
Figure 7: Distribution of tie points allocated on images
As seen in Table 7, the average computational time for the
adjustment was below 3 minutes per image with a o, value of
0.30-0.50 pixel. Experience and literature (Ackermann &
Krzystek, 1997) suggest that pixel sizes smaller than about
20um do not increase the accuracy of the tie points. On the
other hand, high resolutions are required for the clear
identification of control points. Large area coverage involving
100 to 300 points per image is required to ensure high block
stability (Heipke & Eder, 1996).
The automatically determined orientation parameters are more
reliable than those from the analytical solution, since blunders
can be easily detected due to the high redundancy. Another
consequence is that critical cases of the relative orientation,
such as the e.g. the dangerous cylinder, have no practical
significance, since it is virtually improbable for all conjugate
points to lie on such a surface (Heipke, 1997).
Project | Total time/Time per | Average of points per
Image image
1 - g
2 27min / 1.98 min 64
3 47min / 3.38 min 145
4 35min / 4.37 min 114
5 10min / 2.59 min 205
6 27min / 1.51 min 202
7 2h 13min / 11 min 67
Table 7: Time required for AAT and points per image
600
3.5 References
Ackermann, F., Tsingas, V., 1994. Automatic Digital Aerial
Triangulation. Proceedings | of ASPRS/ACSM Annual
Convention and Exposition, Reno Nevada, pp. 1-12.
Ackermann, F., 1996 Some considerations about automatic
digital aerial triangulation. OEEPE — Workshop on Application
of Digital Photogrammetric Workstations (O. Kolbl (Ed.),
OEEPE Official Publications No. 33, pp 157-164.
Ackermann, F., Krzystek, P., 1997. Complete Automation of
Digital Aerial Triangulation. Photogrammetic Record (15)89,
pp. 654-656.
Büyüksalih, G., Zhang, L., 2003. Practical Experiences with
automatic Aerial Triangulation using Different Software
Packages. Photogrammetric Record (18)102, pp. 131-155.
Dórstel, C., Tang, L., Madani M., 2001. Automatic Aerial
Triangulation Software of Z/I Imaging, Proceedings
Photogrammetric Week, Stuttgart University.
Forstner, W., 1986. A Feature Based Correspondence
Algorithm for Image Matching. Int Archives of
Photogrammetry, Vol. 26-111, Rovaniemi.
Heipke, C., Eder, K., 1996. Performance of tie-points
Extraction in Automatic Aerial Triangulation. European
Organization for Experimental Photogrammetric Research
(OEEPE), Official Publication No35, pp125-185.
Heipke C., 1997. Automation of interior, relative, and absolute
orientation. /SPRS Journal of Photogrammetry & Remote
Sencing 52 (1997), pp 1-19.
Jaakola, J., Sarjakoski, T., 1996. Experimental Tests on Digital
Aerial Triangulation. European Organization for Experimental
Photogrammetric Research (OEEPE), Official Publication
No3l, pp 13-57.
Sigle, M., Heuchel, T., 2001. ISAT: Recent Developments and
Performance. Proceedings Photogrammetric Week, Stuttgart
University
Tsingas V., 1991. Automatische Aerotriangulation. Proceedings
43" Photogrammetric Week, Institute For Photogrammetry,
Stuttgart University, pp. 253-268.
Z/1 Imaging, 1999. Imagestation ISAT User's Guide for
Windows NT Operating System.
Zervas, A., Papaharisi, A., 2000. Aerial Triangulation. Common
adjustment of multiple scales and self-calibration. Diploma
Thesis, Lab. Of Photogrammetry, NTUA, 76 pp. (in Greek).
3.6 Acknowledgements
We would like to express our acknowledgements to Dr. B.
Tsingas for his help and advice about the Automatic Aerial
Triangulation. We also wish to thank the Z/I Imaging Hellas
Limited for the support of the appropriate software named
Image Station Automatic Triangulation (ISAT).
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