Visibility Histograms and Visibility-Driven Transfer Functions

—Direct volume rendering is an important tool for visualizing complex data sets. However, in the process of generating 2D images from 3D data, information is lost in the form of attenuation and occlusion. The lack of a feedback mechanism to quantify the loss of information in the rendering process makes the design of good transfer functions a difficult and time consuming task. In this paper, we present the general notion of visibility histograms, which are multi-dimensional graphical representations of the distribution of visibility in a volume-rendered image. In this paper, we explore the 1D and 2D transfer functions that result from intensity values and gradient magnitude. With the help of these histograms, users can manage a complex set of transfer function parameters that maximize the visibility of the intervals of interest and provide high quality images of volume data. We present a semi-automated method for generating transfer functions, which progressively explores the transf...

• Type: Journal
• Year: 2011
• Where: TVCG
• Authors: Carlos D. Correa, Kwan-Liu Ma
• Keywords: Opacity Transfer Functions, Transfer Functions, TVCG 2011, Visibility