Rapid sonic characterisation of sewer change and obstructions.

This paper reports on the development of a low-cost, rapidly deployable sensor for surveying live sewers for blockages and structural failures. The anticipated cost is an order of magnitude lower than current techniques. The technology is based on acoustic normal model decomposition, The instrument emits short coded acoustic signals which are reflected from any sewer wall defect. The acoustic signals can be short Gaussian pulses or longer sinusoidal sweeps and pseudo-random noise. The processing algorithms used on the reflected signal can predict the extent and geometry of the pipe deformation, and the locations and approximate size of common blockages. The effect of the water level on the frequency of the fundamental mode has also been investigated. It is shown that the technique can be adapted to work reliably in relatively large 600 mm diameter sewer pipes.

Congenital breast asymmetry: subjective and objective assessment.

There is currently no standard objective method for the assessment of developmental breast asymmetry. The results of corrective surgery in 24 patients with congenital breast deformities were evaluated subjectively (symmetry scores by patients and panels of observers), and objectively (linear measurements of nipple position and stereophotogrammetrically determined breast volumes). The latter were obtained using a newly developed prototype computer based technique (Bodymap). This study is the first reported use of stereophotogrammetry in assessing results of surgery for the correction of congenital breast asymmetry. The results obtained, their clinical implications, and the usefulness of Bodymap in the objective measurement of breast asymmetry are discussed.

Bodymap: an image processing system for the measurement of body surface profiles encountered in skin expansion surgery.

A personal computer based image processing system for the mapping and subsequent analysis of local areas of the human body requiring no more than 180 degrees of vision is described. The operations of image capture and data extraction are undertaken in real time and photogrammetric reconstruction takes typically a further 30 s. Accuracy of the system has been assessed by photogrammetrically reconstructing 37 points whose coordinates had been precisely established by traditional survey techniques. An average discrepancy between surveyed and reconstructed positions of 0.485 mm was obtained; this level of accuracy compares highly favourably with results achieved using alternative methods and which do not have the level of automation inherent in the described system. The system has been developed specifically to provide quantitative values for parameters of particular interest in skin expansion surgery: consequently the post-reconstruction facilities available in this initial system are surface area and enclosed volume calculations and shaded surface display. Further development work currently in progress is also briefly discussed.