Depth of Field Effects for Interactive Direct Volume Rendering

Abstract

a) 6.1 FPS (b) 3.8 FPS (c) 3.8 FPS (d) 3.8 FPS Figure 1: The backpack data set with 512 × 512 × 373 voxels rendered a) with Phong shading only; and b) with depth of field with α = 30.9 • focused on the spray can in the foreground, c) on the wires behind it and d) on the boxes with the other spray can in the background. In each image 1469 slices were taken and gradients were estimated on the fly. AbstractIn this paper, a method for interactive direct volume rendering is proposed for computing depth of field effects, which previously were shown to aid observers in depth and size perception of synthetically generated images. The presented technique extends those benefits to volume rendering visualizations of 3D scalar fields from CT/MRI scanners or numerical simulations. It is based on incremental filtering and as such does not depend on any precomputation, thus allowing interactive explorations of volumetric data sets via on-the-fly editing of the shading model parameters or (multi-dimensional) transfer functions.

Evaluation of Depth of Field for depth perception in DVR

“…They attribute this to the user having to get used to some part of the image appearing out of focus since they study other techniques for improving the correct perception of depth and DoF is one of the ones they test. To implement DoF in DVR, we referred to the work of Schott et al [26] that describes a DoF technique for slice based Volume rendering. A view-aligned slice based volume renderer is used where the view-aligned slices are blurred according to the distance from the viewer.…”

“…It shows that on both sides of the focal distance z f , we can have regions having similar diameter for the circle of confusion which would translate to the same amount of blur. DoF is implemented as shown in Figure 3 and explained in [26]. A GPU slice based volume renderer is used and the scene is broken down into 2 sections namely before and after the focal plane.…”

“…Two directions are needed to ensure that the in focus region does not contribute to the blurred region. A more detailed description of the algorithm with pseudocode can be found in [26]. …”

“…The DoF technique proposed by Schott et al [26] was implemented in the SLIVR renderer of the VisIt Visualization software [18]. The experiment is run on site to be able to control most experimental parameters including screen quality, luminosity and attention of subjects.…”

Evaluating the perception of semi-transparent structures in direct volume rendering techniques

“…These techniques, all consider depth values in the compositing equation, and have been selected based on initial perceptual findings, and the widespread usage in volume rendering, as determined based on exchange with other researchers and our own experience, as well as the number of citations of the publications proposing these techniques. Thus, we compare standard DVR to Depth of Field rendering [Schott et al 2011], Depth Darkening [Svakhine et al 2009], Volumetric Halos [Bruckner and Gröller 2007], Volume Illustration [Rheingans and Ebert 2001], and Volumetric Line Drawings [Burns et al 2005]. An example for the application of each of these techniques is shown in Figure 1.…”