CMRT09: Object Extraction for 3D City Models, Road Databases and Traffic Monitoring - Concepts, Algorithms, and Evaluation
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As an example, this process is depicted in Figure 9 for
Stuttgart’s Lindenmuseum which has already been illustrated in
Figure 3. There, the original coarse model is shown in
combination with the overlaid 3D point cloud whereas Figure 9
demonstrates the reconstructed facade geometry. The blue
shaded region corresponds to the white polygon in Figure 3 and
indicates the facade geometry that has been generated during
the data driven reconstruction process. All remaining building
parts are modelled based on the grammar inferred from the
marked region.
While in that example the grammar is applied for the
completion of facade structure, it can also be used as a “library”
to generate building facades for objects, where no measurement
is available at all. This step is demonstrated in Figure 10 where
facade geometry was synthesized for a number of residential
houses. Since these building were not covered by any sensor
data at all, a range of grammars was derived in advance from a
few buildings in the near environment. Similarly, the
applicability of our facade grammars to a larger scene using
grammars which represent compatible architectural styles is
shown in Figure 11.
4. DISCUSSION
Within the paper an automatic approach for the geometric
modelling of 3D building facades was proposed. Based on
observed 3D point clouds from a mobile mapping system,
grammar rules are extracted, which can then be used to generate
synthetic facade structures for unobserved building parts.
Despite the good geometric accuracy which is feasible for
terrestrial point clouds such data frequently suffer from the
unavailability of measurements for hidden building parts. This
problem is solved by extracting the grammar from observed
street-facing facades and then applying it for the improvement
and completion of remaining facade structure in the style of the
respective building. Moreover, knowledge propagation is not
restricted to facades of one single building. Based on a small set
of facade grammars derived from just a few observed buildings,
facade reconstruction is also possible for whole districts
featuring uniform architectural styles. Due to these reasons the
proposed algorithm is very flexible towards different data
quality and incomplete sensor data.
5. REFERENCES
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Figure 11. Facade geometry for larger area
