O.: Smooth mixed-resolution gpu volume rendering

We propose a mixed-resolution volume ray-casting approach that enables more flexibility in the choice of down-sampling positions and filter kernels, allows freely mixing volume bricks of different resolutions during rendering, and does not require modifying the original sample values. A C0-continuous function is obtained everywhere with hardware-native filtering at full speed by simply warping texture coordinates of samples in transition regions. Ad-ditionally, we propose a simple but powerful, flat texture packing scheme that supports mixing different resolution levels in a single 3D volume cache texture with a very simple and fast address translation scheme. Although this packing constrains full scalability, it enables mixing different resolution levels in GPU-based ray-casting with only a single rendering pass. We demonstrate our approach on large real-world data, obtaining a continuous scalar function and shading at brick boundaries, using single-pass ray-casting at real-time frame rates