Abstract: This document describes systems and methods for, among other things, visualizing 3D volumetric data comprising voxels using different segmentation regions. A segmentation mask vector is associated with each voxel, which defines to which segmentation region that voxel belongs. During the visualization, segmentation masks are interpolated to obtain a vector of segmentation mask weights. For each sample point, a vector of visualization values is multiplied by a vector of segmentation mask weights to produce a composite fragment value. The fragment values are combined into pixel values using compositing. The systems and methods leverage the computational efficiency of commodity programmable video cards to determine accurately subsampled partial contribution weights of multiple segmented data regions to allow correct per-fragment combination of segment specific characteristics such as color and opacity, which is suitable for many applications, including volume rendering.