Proceedings PaperAutomatic Building Of Qualitative 3-D Rock Models For Landmark Recognition
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Rocks are natural landmarks for navigation by mobile robots through natural terrain, particularly rocky terrains. In order to use rocks as landmarks, the robot must be able to recognize such landmarks. For the robot to navigate effectively, it must also be able to automatically construct models of rocks to be used as new landmarks. This paper presents an approach to the automatic building of qualitative 3-D models for the rocks world; a world in which accurate quantitative models of objects are hard to obtain. The model is a graph where the nodes represent surface patches on the rock and the arcs represent the adjacency relationships between them. Shapes of surface patches are qualitatively described as types using a small set of possible types. With a camera mounted on a robot arm, a model is constructed from multiple views of the object. Starting with an initial view, the partial knowledge extracted is used for planning new camera positions. These new positions are needed for acquiring more knowledge about the object, e.g. the shapes and adjacency relationships of surfaces that are on the other side of the rock or that are only partially visible. As new knowledge is acquired, the model is updated and more new camera positions planned when necessary. The process is repeated until no additional knowledge can be acquired from the new positions. An example is used to illustrate how a rock model is built. The robustness and weaknesses of the approach are discussed. Suggestions for improvements are also included.