We show how to recover 2D structure and motion linearly in order to initialize Simultaneous Mapping and Localization (SLAM) for bearings-only measurements and planar motion. The method supplies a good initial estimate of the geometry, even without odometry or in multiple robot scenarios. Hence, it substantially enlarges the scope in which non-linear batchtype SLAM algorithms can be applied. The method is applicable when at least seven landmarks are seen from three different vantage points,

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... er by one robot that moves over time or by multiple robots that observe a set of common landmarks.