Authors: Shengzhou Luo, John Dingliana
Abstract: We present an interactive approach for intuitively editing colors and opacity values in transfer functions for volume visualization. We introduce the concept of a relative visibility histogram, which represents the difference between the global visibility distribution across the full volume and the local visibility distribution within a user-selected region in the viewport. From this measure we can infer what the user intends to select when they click on a specific region in the viewport and use this result to directly modify the relevant parts of the transfer function. The approach is lightweight compared to similar techniques and performs in real-time.