A new algorithm of maximum intensity projection based on context-preserving illustrative volume rendering model

Maximum Intensity Projection (MIP) is one of the most common methods for the visualization of volumetric data. MIP works by traversing all viewing rays and finding the maximum data value along each of them. The main limitation of MIP is that it cannot adequately depict the spatial relationships of overlapping tissues. Context-preserving illustrative volume rendering model is an extension to direct volume rendering (DVR). In volume rendering this model can simultaneously visualize interior and exterior structures while preserving clear shape cues using a function of shading intensity, gradient magnitude, distance to the eye point, and previously accumulated opacity to selectively reduce the opacity in less important data regions. It is controlled by two user-specified parameters. In this paper, we advance MIP based on this model. On one hand, we improve the opacity computation method correspond with the Context-preserving illustrative volume rendering model. On the other hand, for lighting of the objects the Phong-shading is employed in the new algorithm. Through shading and combining MIP with the Context-preserving illustrative volume rendering, the new MIP images greatly communicate 3D shape, depth information. Furthermore, we show that the new algorithm achieves real-time performance on current graphics hard-ware.