252
4. A selection of DIPS II-based projects
The following is a brief survey of research and
development projects, which were recently
executed on DIPS II. Further details can be found
in the referenced literature.
measurement by the least squares template
matching technique (for details see Wilkins,
1990a). Figure 6 shows a typical scanned image of
a signalised point after digitisation.
ULD1F - Development Lnvironmcnt I
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Figure 5: Large testfield for CCD camera calibration; shown within DEDIP with panels for “Interactive
Target Location” and “Image Processing”
4.1. CCD camera calibration
We have two three-dimensional testfields of
different size in use for geometric camera
calibration. One testfield consists of a metal plate
(size 50x50 cm 2 ) with 25 retro-reflective targets on
it. The plate can be positioned parallel to itself so
that a 3-D pointfield will result. The movement of
the plate is continuous, its position is measured by
rotary encoders. Results of calibration and point
positioning accuracy are reported in Beyer,
1987.Our large testfield (size 3.2 x 2 x 1.2 m 3 ),
which consists of 136 targets marked on a wall and
five vertical rods with 50 additional targets (all
targets have two sizes each) each is shown in
Figure 5. Calibration and point positioning results
are reported in Baltsavias, Stallmann, 1990.
4.2. High accuracy point positioning
Two typical examples from distinctively different
applications are reported here. One is a semi
automatic aerial triangulation, where signalised
points are measured in aerial photographs on the
S9-AP by coarse operator positioning and fine
Figure 6: Scanned image of a signalised point in
an aerial photograph. The overlaid quad
rangles show the location and size of the
digitized patch before and after template
matching. Also shown is the path which
the template takes during the iterations
of the matching process.