1. A real-time object detection and tracking system comprising, embodied in one or more computer accessible storage media: an object tracking (OT) node to detect and track one or more objects in a group of objects depicted in a video stream produced by a camera having a field of view arranged to acquire images of a real-world environment, by: detecting a plurality of parts of objects in the group of objects, each of the detected parts being less than an entire object; inferring a spatial relationship between at least two of the objects in the group of objects based on the detected parts; and outputting a local track for one or more of the objects in the group of objects, the local track comprising a unique identifier and a geo-location of one or more of the objects at different time instants of the video stream.