PHD Thesis - Institute for Computer Graphics and Vision - Graz ...

8.2. Map building experiments 139
8.2.2 Hallway environment
The second mapping experiment has been conducted in a hallway of our university building.
The ”Hallway” environment is a very challenging environment. First, the area to be mapped is
large, 30m × 8m. Second, the environment consists of lots of un-textured areas. A total number
of 2293 images has been acquired by multiple robot runs. The robot runs were performed on
different days too. A selection of the whole image set was used to create the world map. For
map building first sub-maps have been identified within the image set. In a next step each
identified sub-map has been reconstructed. The last map building step was the linking of the
sub-maps. Map building resulted in the reconstruction and linking of 13 sub-maps. Table 8.2
summarizes the details of the ”Hallway” map. Figure 8.9 shows two views of the piece-wise
planar world map in 3D. A bird’s eye view of the map is shown in Figure 8.8. Each sub-map is
shown in a different color. The color coding reveals the sub-map structure of the whole map. It
is visible from the color coding that the sub-maps differ in size. The upper right part of the map
contains a high number of small sub-maps. In that area the sub-maps overlap substantially. The
sub-maps in the lower part are bigger. In the lower part sub-map linking has to be performed
over wide baselines. The upper and lower part of the map are linked only by a single landmark
contained in the upper left sub-map (brown). Despite linked by a single landmark only both
parts are nicely parallel and show the capabilities of the sub-map reconstruction and linking
methods.
”Hallway” map intrinsics
Number of sub-maps 13
Number of planes 37
Number of landmarks 2093
Map size [m] 30 × 8
Table 8.2: Intrinsics of the ”Hallway” map.