Interactive Editing of Volumetric Objects by Using Feature-Based Transfer Function

This chapter focuses on the rendering of fluids represented by volumetric datasets. Generally, volume data can be visualized by a volume rendering technique. The result depends on the transfer function that converts a volume data into a colored volume. However, it is often difficult to create desired images by manually adjusting the transfer function. We propose an intuitive system that allows the user to directly design the appearance of the volume by specifying colors of the volume with a set of control points. The system solves an inverse problem to determine the transfer function such that the color of the rendered image becomes the same as those of the control points. In our method, the transfer function defined as a multi-dimensional function of features computed from the input volume dataset. Our method represents the transfer function as a linear combination of radial basis functions in order to efficiently solve the inverse problem.