1. Anandan, P. (1989), “A computational framework and an algorithm for the measurement of visual motion”, International Journal of Computer Vision, Vol. 2 No. 3, pp. 283‐310.
2. Bayliss, C. (1996), Transmission and Distribution Electrical Engineering, Butterworth Heinemann, London.
3. Bhanu, B., Das, S., Roberts, B. and Duncan, D. (1996), “A system for obstacle detection during rotorcraft low altitude flight”, IEEE Trans Aerospace and Electronic Systems, Vol. 32 No. 3, pp. 875‐97.
4. CAA (1995), CAP658 Small (Model) Aircraft: A Guide to Safe Flying, Civil Aviation Authority, London.
5. Clot, A. (2001), “A closer look”, Unmanned Vehicles, Vol. 6 No. 2, pp. 12‐16.