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Modern Geomatics Technologies and Applications

Figure 8. RANSAC algorithm

2.2.3 Building Utility Modelling: As can be seen from the Figure1, the LoD3 displays not only the information and
structure of the roofs, but also gives information about the facades too. Initially, we separated and modelled the roofs and
then extracted facades by considering boundary situation of roofs. Since the walls follow a cube shape, they can be modelled
by a fitting cube to the separated walls.

3. Experiment and Results

3.1. Study Area
This research was estimated using ALS and MLS data collected from an urban area in Stuttgart, Southwest of Germany.
The study area includes various features such as buildings, trees and cars. Figure 9-a illustrates aerial image of this study area
and collected point clouds of this study area is shown in Figure 9-b.

(a) (b)

Figure 9. Study area: (a) Top view image of study area; (b) Collected point clouds

3.2. Results
Similar to conventional procedures, raw point clouds sectioned to several parts. ALS point clouds include 4764142 points.
Figure 10 shows a sample section of the point cloud. In sectioning, data were produced six square sections, the dimensions of
each section are 100 × 100 meters. Because the buildings may fall on the border of sections, there should be 5 meters overlap
between sections.

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