Research On Multimodal Visualization Of Heart

Contraction and relaxation of the heart which provide the impetus for thebody’s blood circulation is the body’s source of power. However, cardiovasculardiseases have been the threat to health of human being. Due to the high cost and lowefficiency of clinical study on the heart, the research of the virtual heart can developrapidly. The research of the virtual heart has recently focused on the visualization ofthe cardiac anatomical data and the modeling of cardiac electrophysiologicalprinciple.The rendering speed of the CPU-based visualization is slow when using volumerendering to visualize the cardiac anatomical data as the amount of the cardiacanatomical data is huge, so it is difficult for the user’s real-time interaction.Compared to CPU, there are more ALU on GPU and GPU has also achieved thebasic operation of the image, so GPU is faster than CPU on the graphics and imageprocess. Visualization of the cardiac anatomical data using GPU-based ray castingalgorithm is fast and can achieve real-time interaction.The design of1D histogram based transfer function is firstly introduced tomake the heart tissue distinguish. Opacity modulation based on statistics of thespecific gray level is then presented to observe the interior subtle cardiac tissuesclearly.2D histogram based transfer function using gray level and gradientmagnitude is implemented to get clear contour of heart and to enhance boundaries ofcardiac tissues. Transfer function using the mean and standard deviation is presentedfor the extraction of the boundary of heart tissues.4D visualization is a difficulty in the field of scientific computing visualization,time histogram is used to divide the4D data of cardiac electrophysiology intodifferent time periods according to the characteristics of4D data of cardiacelectrophysiology. The adaptive transfer function is designed for each time periodand GPU-based ray casting algorithm is improved for4D visualization. Therendering results show that the proposed method can show more details of thechanges of cardiac electrophysiology in each time period.The fusion of multimodal visualization is division into the fusion of materialproperties, fusion of optical properties and fusion of image based on the change ofthe data flow in the ray casting algorithm in order to observe heart objectively. Thefusion framework is applied to the fusion visualization of the cardiac anatomicaldata and its boundary and the fusion visualization of the cardiac anatomical data andthe cardiac electrophysiological data. The structure of the heart tissues can be moreobjectively observed and cardiac electrophysiological principles can be comprehensively understood through multimodal visualization.