| Volume 26 Issue 2 - Publication Date: 1 February 2007 |
| Special Issue on the Fifth International Conference on Field
and Service Robotics, 2005 |
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| An Efficient Extension to Elevation
Maps for Outdoor Terrain Mapping and Loop Closing |
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| P. Pfaff, R. Triebel
and W. Burgard Department of Computer Science, University of Freiburg,
79110 Freiburg, Germany |
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| Elevation maps are a popular
data structure for representing the environment of a mobile robot operating
outdoors or on not-flat surfaces. Elevation maps store in eachcell of a
discrete grid the height of the surface at the corresponding place in the
environment. However, the use of this 212 -dimensionalrepresentation, is
disadvantageous when utilized for mapping with mobile robots operating on
the ground, since vertical or overhanging objects cannot be represented
appropriately. Furthermore, such objects can lead to registration errors
when two elevation maps have to be matched. In this paper, an approach is
proposed that allows a mobile robot to deal with vertical and overhanging
objects in elevation maps. The approach classifies the points in the environment
according to whether they correspond to such objects or not. Also presented
is a variant of the ICP algorithm that utilizes the classification of cells
during the data association. Additionally, it is shown how the constraints
computed by the ICP algorithm can be applied to determine globally consistent
alignments. Experiments carried out with a real robot in an outdoor environment
demonstrate that the proposed approach yields highly accurate elevation
maps even in the case of loops. Experimental results are presented demonstrating
that that the proposed classification increases the robustness of the scan
matching process. |
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| Multimedia Key |
= Video |
 = Data |
= Code |
= Image |
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Extension |
Type |
Description |
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1 |
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Example
1: Incremental registration of two original point clouds. (1.1
MB) GIF |
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2 |
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Example
2: Triangulated mesh representation of the outer loop including
data points from 77 laser scans. The extension shows a virtual walk
through this model on the trajectory taken by the robot. (5.2 MB)
mpg |
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