Method, system and apparatus for determining a lowest point of a target object in an image

A method of determining a lowest point of a target object in an image of a scene. A region of the target object in the image is received. A horizontal vanishing line of the image is received. At least one reference object in the scene is selected. At least a first line connecting the received region of the target object and a highest point of the reference object is determined. At least an intersection point of the first line and the horizontal vanishing line is determined. At least a second line connecting the determined intersection point to a lowest point of the reference object is determined; and a lowest point of the target object is determined based on the second line.