The invention is related to methods and apparatus that use a visual sensor and
dead reckoning sensors to process Simultaneous Localization and Mapping (SLAM).
These techniques can be used in robot navigation. Advantageously, such visual techniques
can be used to autonomously generate and update a map. Unlike with laser rangefinders,
the visual techniques are economically practical in a wide range of applications
and can be used in relatively dynamic environments, such as environments in which
people move. One embodiment further advantageously uses multiple particles to maintain
multiple hypotheses with respect to localization and mapping. Further advantageously,
one embodiment maintains the particles in a relatively computationally-efficient
manner, thereby permitting the SLAM processes to be performed in software using
relatively inexpensive microprocessor-based computer system.