Recognition of Elevation Value in Topographic Maps by Multi-Angled Parallelism

We have proposed the MAP (Multi-Angled Parallel) operation method which extracts geometric features from a topographic map using erosion-dilation operations on a directional feature field. We have also proposed the MAP matching method which recognizes fixed-shaped symbols in the topographic map by using parallel operations on the same directional feature field. We have shown that all kinds of feature extraction and recognition can be effectively performed within the framework of parallel operation. In this paper, we show that elevation values in a topographic map can be recognized by a combination of MAP operation with the MAP matching. Numerals and symbols are recognized by the MAP matching method, while small dots and lines are extracted by the MAP operation method. These results are used together to determine the value, position and attribute of elevations in topographic maps.