Building and maintaining computer representations of two-dimensional mine maps

We present algorithms that allow a computer-assisted underground coal mining system to do real-time conversion between two representations of spatial occupancy, namely, certainty grids and object boundary curves. These algorithms can be used to accomplish many tasks of an underground mining vehicle such as mapping, navigation, object recognition, vehicle localization, and vehicle motion simulation. For conversion from certainty grid to object boundaries, an edge linking algorithm [1] is appropriately modified. Certainty grid ‘images’ are transformed into a set of object boundary curves. The latter are expressed as oriented piecewise linear segments. Image processing techniques, such as edge detection, thinning, curve tracing, and linear approximation are employed with various modifications. The certainty grid to object boundary algorithm is tested against simulated noisy certainty grid maps. Finally, an algorithm to convert object boundary curves to an occupancy grid is presented.