Research On Three-dimensional Image Visualization For Electrical Capacitance Tomography

It is important to measure the parameters of two-please flow in industrial and scientific research. Electrical capacitance tomography (ECT) is a Process Tomography (PT) based on capacitance sensor; it can provide 2D/3D interior behavior information in process equipment, e.g. closed pipe, vessels and so on in real time. ECT has the advantage of being non-intrusive, fast in response, simple in structure, high safety and low in cost, so it is one technique which has great developing potential in field of petroleum, chemical engineering and so on.The 3D ECT image visualization researched in this paper is based on 2D recosntructuion images, which means good 2D image quality and fast image speed is required. Currently, Landwever iterative is the most widely used iterative ECT image reconstruction method for its good performance. Modified iterative Landweber method and Landweber iterative-single step method are discussed in this paper. The simulation results show that modified iterative Landweber method accelerates the reconstruction speed and enhance the reconstruction quality over the conventional Landweber iterative method; and images quality reconstructed by Landweber iterative-single step method is similar to that of conventional Landwerber iteration, while the reconstruction speed is similar to that of LBP method.3D image presentation for capacitance tomography is discussed and implemented in this paper by employing 3D medical image reconstruction methods. Based on the distributed data of the two-phase flow section obtained from ECT system, the method of contour connection and MC method are adopted to reconstruct 3D images. 3D image reconstruction by contour connection method involves contour extracting, contour matching, contour interpolation and 3D image surface reconstruction. In this paper, the contour extracting is implemented by a simple and straight correlation-operation on the cross-section images; the contour matching is realized using a method based on angle sample; the contour interpolation is achieved by using B spline interpolation, and finally, the method of shortest-diagonal is used to reconstruct triangle surface between two adjacent contour lines. MC algorithm is a classical algorithm to extract iso-surfaces from regular volume data. Through the experiment on this method, the theory about cutting cubes and problems of constructing iso-surfaces is discussed. 3D reconstruction and better visualization results are given and discussed.In order to control ECT system running and view the medium distribution in the pipeline real-time, the software for the 16-electrodes ECT system is developed in VC++6.0 and MATLAB. The functions of human-computer interaction, 2D image reconstructing, communication with lower-computer, and the like, are implemented using VC++6.0, 3D image reconstruction is implemented using MATLAB.