Helbilds 3D-avbildning

An investigation was initiated, targeting snapshot 3D image sensors, with the objective to match the speed and resolution of a scanning sheet-of-light system, without using a scanning motion. The goal was a system capable of acquiring 25 snapshot images per second from a quadratic scene with a side from 50 mm to 1000 mm, sampled in 512×512 height measurement points, and with a depth resolution of 1 µm and beyond. A wide search of information about existing 3D measurement techniques resulted in a list of possible schemes, each presented with its advantages and disadvantages. No single scheme proved successful in meeting all the requirements. Pulse modulated time-of-flight is the only scheme capable of depth imaging by using only one exposure. However, a resolution of 1 µm corresponds to a pulse edge detection accuracy of 6.67 fs when visible light or other electromagnetic waves are used. Sequentially coded light projections require a logarithmic number of exposures. By projecting several patterns at the same time, using for instance light of different colours, the required number of exposures is reduced even further. The patterns are, however, not as well focused as a laser sheet-of-light can be. Using powerful architectural concepts such as matrix array picture processing (MAPP) and near-sensor image processing (NSIP) a sensor proposal was presented, designed to give as much support as possible to a large number of 3D imaging schemes. It allows for delayed decisions about details in the future implementation. It is necessary to relax at leastone of the demands for this project in order to realise a working 3D imaging scheme using concurrent technology. One of the candidates for relaxation is the most obvious demand of snapshot behaviour. Furthermore, there are a number of decisions to make before designing an actual system using the recommendations presented in this thesis. The ongoing development of electronics, optics, and imaging schemes might be able to meet the 3D snapshot demands in a near future. The details of light sensing electronics must be carefully evaluated and the optical components such as lenses, projectors, and fibres should be studied in detail