Some problems exist in computing gradient

proxy polygon and pre-integration in GPU ray-casting for uniform grid and cracks may be easily produced in multi-block GPU ray-casting. To address these issues

improved GPU ray-casting for uniform grid is designed and implemented in this paper. Main improvements include an improved gradient computing method where that gradient is computed on need and on physical space and upper limit of gradient magnitude is evaluated

single pass GPU pre-integration

volume clipping method that is utilized to compute proxy polygon correctly and crack-free method for multi-block GPU ray-casting. Improved GPU ray-casting in this paper facilitates gradient magnitude modulation so that the interesting substances can be highlighted. It can compute pre-integration rapidly so that one can modify transfer function interactively and interesting features can be found quickly. Volume can be rendered correctly with it and one can peel the front thing and see the internal things. Crack is free when it renders multi-block dataset.