International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
Figure 2. The produced model has an average resolution of 2
cm with more than 10 million triangles.
Figure 2. 3D Model of Al-Khasneh created from 5 scans
In additional to the outer survey, a 360-degree scanning from a
station in the interior of the Al-Khasneh had been taken, which
resulted in 19 million points. Figure 3 shows the point cloud of
this scan with colour information overlaid.
Figure 3. 360 degree scanning for the inner part of Al-Khasneh
3. INTEGRATED DATA PROCESSING
Although the 3D model produced by laser scanner contains a
large number of triangles, which are representing the surfaces, it
can still difficult to recognize and localize the outlines of the
surface features. An example for this type of features, which are
clearly visible in an image is depicted in figure 4. This data was
collected from the left door of Al-Khasneh. As it can be seen
from the corresponding 3D meshed model shown in figure 5,
these cracks and the edges outlines are lost beyond the resolu-
tion in the available laser data.
Figure 4. The left door of Al-Khasneh
In order to support the visual quality of such details, a hybrid
approach combining data from the laser scanner and the digital
imagery was developed. For integration all data sets have to be
coregistered in the first processing step. This is realized by
aligning the extracted edges from both data sources using an al-
gorithm developed by [Klinec and Fritsch, 2003]. After position
and orientation parameters are computed for the sensor stations,
distance images are generated from the point cloud in order to
provide the missing third dimension in the available images. Fi-
nally, an integrated segmentation process based on the image
data is be used in order to support the extraction of the details
and the surface features outlines from distance images. Addi-
tionally, the approach applies a semi-automated feature extrac-
tion from images to bridge gaps in the laser scanner data. By
these means details can be added that are necessary for generat-
ing more realistic perceptions of the scene volume. In the fol-
lowing paragraphs the hybrid approach will be discussed in
more details. The left door of the Al-Khasnch depicted in figure
4 and 5 is exemplarily processed.
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