Instead, three
similarity measurements of the area around a detector in two
consecutive frames were used to detect the presence of
vehicles. Patch analysis was then performed to determine the
number of vehicles in the detector area. Liu et al. [4] proposed
a real-time vehicle counting methods based upon virtual
detection line and spatio-temporal contour techniques.
Specifically, GMM was used to detect moving foreground
pixels on the detection line in each frame. By combining this
information of several consecutive frames, a contour of a
vehicle in the spatio-temporal domain could be constructed.
This contour was then analyzed to determine the number of
vehicles. Some other algorithms for shadow detection and
shadow removal were proposed in [5,6].