Position and Vector Detection of Blind Spot motion with the Horn-Schunck   Optical Flow
  The proposed method uses live image footage which, based on calculations of pixel motion, decides whether or not an object is in the blind-spot. If found, the driver is notified by a sensory light or noise built into the vehicle's CPU. The new technology incorporates optical vectors and flow fields rather than expensive radar-waves, creating cheaper detection systems that retain the needed accuracy while adapting to the current processor speeds. 
Stephen Yu, Mike Wu
cs.CV