1. An obstacle detection method, comprising: (a) disposing a camera at a vehicle, the camera having a field of view external of the vehicle; (b) acquiring a series of image frames captured by the camera whilst the vehicle is in motion, the image frames defining an image plane having a vertical aspect and a horizontal aspect; (c) detecting, via processing of captured image frames by a processor, a first object present in the series of image frames by edge detection; (d) detecting, via processing of captured image frames by the processor, a second object present in the series of image frames by edge detection; (e) for the first detected object, (i) selecting, via a control that comprises the processor, and responsive to processing of captured image frames by the processor, first and second feature points from the first detected object that are spaced apart in a first image frame, (ii) tracking, via processing of captured image frames by the processor, positions of the first and second feature points over at least a second image frame, and (iii) determining, via processing of captured image frames by the processor, movement of the first and second feature points when projected to the image plane; (f) for the second detected object, (i) selecting, via the control, and responsive to processing of captured image frames by the processor, third and fourth feature points from the second detected object that are spaced apart in a first image frame, (ii) tracking, via processing of captured image frames by the processor, positions of the third and fourth feature points over at least a second image frame, and (iii) determining, via processing of captured image frames by the processor, movement of the third and fourth feature points when projected to the image plane; (g) comparing, via the control, the movement of the first and second feature points when projected to the image plane to the movement of the third and fourth feature points when projected to the image plane; (h) distinguishing, via the control, between the first detected object being a three dimensional object and the second detected object being a two dimensional object by determining, via the control, that the movement of the first feature point when projected to the image plane is dissimilar to that of the second feature point and by determining, via the control, that the movement of the third feature point when projected to the image plane is similar to that of the fourth feature point; and (i) making, via the control, and responsive to processing of captured image frames by the processor, a trajectory estimation of the first detected object and, based on the trajectory estimation, determining, via the control, whether the first detected object is in a path of movement of the vehicle.