基于实时梯度计算的快速纹理映射体绘制

本文分析讨论了一种基于实时梯度计算的纹理映射体绘制算法。在绘制过程中实时计算每个体素上的梯度，有效地减少了在传统基于纹理映射的体绘制中，对梯度预先计算的耗时操作，也降低了内存的消耗，加快了整个绘制过程。同时，采用三维Sobel算子对梯度进行计算，并进行归一化处理，有效地提高了绘制图像的质量。在实现中充分利用了目前PC图形硬件成熟的可编程特性，特别是fragment program，来完成梯度的实时计算。最后对医学体数据进行绘制，得到了理想的结果。

Real-time Gradient Estimating in Texture-Based Volume Rendering

A novel technique for texture-based volume rendering is discussed,which estimates and normalizes the gradient on the fly.During rendering the gradient is calculated on each voxel,and normalized for the lighting computation.The new technique is presented to load the volume dataset to the 3D texture directly without the time consumptive process to pre-compute the gradient,and circumvent the huge memory consumption in previous approaches.Additionally,the 3D Sobel gradient operator is applied to the gradient estimation,which improves the quality of the rendering.The sophisticated PC graphics hardware functionality is utilized,especially the fragment program,to implement the gradient estimation.Several examples are given to illustrate the effectiveness on real clinic 3D CT datasets.