Indirect method to estimate distance measurement based on single visual cameras

In this paper, we proposed an indirect method to measure the distance of an object accurately by single visual cameras using triangulation. The object can be seen as the third point of a triangle with two known sides and one known angle. Distance to object can be determined indirectly on the base of known sides and angle, rather than being measured directly. It would be very useful in case there is no line of sight to object (inaccessible) or an obstacle interrupts it. Furthermore, the results show that the measured distance using the indirect method has a less measurement error than the one using the direct method. This method establishes a basis for the implementation of the position algorithm into the navigation subsystem of swarm robots and will be very helpful especially in robot cooperation.