Research On 3D Medical Image Visualization Technology Based On Volume Rendering

With the improvement of visualization technology, medical image visualization is becoming more and more useful in the aspect of disease diagnosis and computer-aided education. Surface rendering and volume rendering are two important technologies in medical image visualization. Surface rendering makes use of interim geometric elements and is unable to retain the whole information of the image; however, volume rendering renders the volume data directly, which is able to display the inner hierarchical relations of the object and to exhibit plentiful 3D information.3D medical image visualization system based on volume rendering renders the volume data directly using ray casting algorithm. With the Phong illumination model, shading adjusting is attained to achieve the goal of three dimensional rendering. In terms of ray casting implementation, transfer function is improved. Owing to the bad rendering effects and the low fidelity resulted from traditional transfer functions, the transfer function based on continuous gradients is proposed to improve the rendering quality. In terms of illumination model, owing to the deficiency of object radiation and pigment filtering of the Phong illumination model, an improved model based on radiosity and the Phong model is adopted, which improves the display fidelity of the scene. Moreover, owing to the diverse requirements of the rendering quality and rendering speed for different users, the multiple matching modes of resampling, interpolation and composition are used to meet the needs of users to the maximized extent.It is proved by the system functional tests and performance tests that the improved transfer function solves the problem of object conglutination resulted from opacity transfer function, and abrupt colour transition resulted from colour transfer function, which improves the rendering fidelity. The improved model based on radiosity and the Phong model solves the problem of deficiency of surface radiation and pigment filtering, which augments the rendering effect of three dimensional image.