OpenStreetMap has announced a Bing API to detect roads. I want to know what is the theory behind road detection and if there is any open source tool that do that.
The first is "Create Vector". The bitmap [Raster] is translated to vector notation as soon as possible. That is, each single bit is converted into four directional vectors, joined as a square.
The second is "Simplify Vector". The vector field is simplified by checking for duplicates and removing the vectors that are lying on top of each other (these would be adjacent bits in the bitmap). This is done by referring to the links to the identical vectors and merging these, much like one would remove an item from a linked list.
The third and last is "Lengthen Vector". The algorithm goes through the modified vector field looking for joined parallel vectors and turns these multiple vectors into a single vector.
and see the IBM patents http://www.ibm.com/search/csass/search?sn=mh&q=vectorization&lang=en&cc=us&en=utf