Besides the mentioned methods for modeling dynamical
spatial processes it is also possible to use slices of
different STCs taken at the same time and to build a
spatial model using stereo matching algorithms
[Förstner, 1986]. In that case different models has to be
linked in object space with the help of surface matching.
This approach needs synchronisation of the different
cameras, otherwise no surface for one fixed moment can
be determined.
Both methods described in this paper work even without
synchronisation, because in a first step the STCs are
analysed separately and then the motion curves of
corresponding points are determined. Therefore, points at
any moment can be interpolated if necessary, before
computing the 4D co-ordinates of the points of the
motion model by spatial intersection.
4. CONCLUSIONS
In each of the mentioned cases the result is a motion-
model with the axes X, Y, Z and T. In a model of that
type it is possible to obtain a surface for one fixed
moment (T = constant). This is done by first computing
the respective points for the selected value of T on each
of the spatial curves and then building the surface
description. This static surface can now be analysed
visually and geometrically. Besides the selection of one
fixed T it is also possible to analyse the motion and
changes of one fixed co-ordinate level (e.g.
Z = constant) by showing and analysing the contour lines
at different times.
The possibility to visualise the movement of objects
which has been determined by high precision
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996
photogrammetric measurement is rather new and offers
totally new areas of application for photogrammetry.
This research project has been supported by the Austrian
Science Foundation, Project number P10354-MED.
REFERENCES
Jàhne, B., 1993. Spatio-Temporal Image Processing.
Lecture Notes in Computer Science 751. Berlin
Heidelberg, pp. 120 - 132.
Fórstner, W., 1986. A Feature Based Correspondence
Algorithm for Image Matching. In: International Archives
of Photogrammetry and Remote Sensing, Vol. XXVI,
Part 3, pp. 11 17:
Förstner, W., 1987. A Fast Operator for Detection and
Precise Location of Distinct Points, Corners and Centres
of Circular Features, ISPRS Intercommision Workshop
on "Fast Processing of Photogrammetric Data”,
Interlaken, pp. 281 - 305.
Gruen, A., 1985. Adaptive Least Squares Correlation: A
Powerful Image Matching Technique, South African
Journal of Photogrammetry, Remote Sensing &
Cartography, Vol. 14, No. 3, pp. 175 - 187.
Kraus, K., 1993. Photogrammetry Volume 1 -
Fundamentals and Standard Processes, Dümmler /
Bonn, pp. 276 - 290.
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