A computerized method of video analysis that includes receiving several series of video frames generated by a number of image sensors. Each image sensor has its own field-of-view which can, but does not have to, overlap with another image sensor's field-of-view. The image sensors monitor a portion of a monitored environment. The computerized method also includes concurrently tracking, independent of calibration, multiple objects within the monitored environment as the objects move between fields-of-view, and multiple objects within one field-of-view. The tracking is based on the plurality of received series of video frames.