Coverage-based opacity estimation for interactive Depth of Field in molecular visualization

Abstract

Figure 1: Thermus thermophilus 70S ribosome (PDB ID: 2WDK) rendered with no Depth of Field effect (left) and using our approach focusing on near structures (center) and far away structures (right). ABSTRACTIn this paper, we introduce coverage-based opacity estimation to achieve Depth of Field (DoF) effects when visualizing molecular dynamics (MD) data. The proposed algorithm is a novel object-based approach which eliminates many of the shortcomings of state-of-the-art image-based DoF algorithms. Based on observations derived from a physically-correct reference renderer, coverage-based opacity estimation exploits semi-transparency to simulate the blur inherent to DoF effects. It achieves high quality DoF effects, by augmenting each atom with a semi-transparent shell, which has a radius proportional to the distance from the focal plane of the camera. Thus, each shell represents an additional coverage area whose opacity varies radially, based on our observations derived from the results of multi-sampling DoF algorithms. By using the proposed technique, it becomes possible to generate high quality visual results, comparable to those achieved through ground-truth multi-sampling algorithms. At the same time, we obtain a significant speedup which is essential for visualizing MD data as it enables interactive rendering. In this paper, we derive the underlying theory, introduce coverage-based opacity estimation and demonstrate how it can be applied to real world MD data in order to achieve DoF effects. We further analyze the achieved results with respect to performance as well as quality and show that they are comparable to images generated with modern distributed ray tracing engines.

Visualization of Biomolecular Structures: State of the Art Revisited

“…Kottravel et al . [KFSR15] recently proposed an object‐space approach for DoF utilizing a coverage‐based opacity estimation which can be computed at interactive frame rates. The DoF effect can also be adjusted to highlight semantic properties [KMH01] like single bonds or charge densities within a protein.…”

“…In molecular visualization, DoF can be used to draw the attention of the user to a specific region and is computed interactively in image space [FKE13]. Kottravel et al [KFSR15] recently proposed an object-space approach for DoF utilizing a coverage-based opacity estimation which can be computed at interactive frame rates. The DoF effect can also be adjusted to highlight semantic properties [KMH01] like single bonds or charge densities within a protein.…”

Real-Time Molecular Visualization Supporting Diffuse Interreflections and Ambient Occlusion

“…In order to do so, a grid is computed that stores the occupancy information derived from the neighboring atoms, which enables AO in real-time. Kottravel et al introduces depth-of-field techniques to molecular rendering, which provides additional depth cues to the user [25]. To speed up rendering, many authors exploit deferred shading techniques in molecular visualization [13,18,32].…”

Minimizing cyber sickness in head mounted display systems: Design guidelines and applications

“…But, even with a lack of good hardware implementation, improperly design content will contribute to an unhealthy experiences. Different depth of field (DoF) simulation techniques were proposed in computer graphics, in order to generate realistic scenes [10]. Virtual reality and general entertainment applications often use such techniques to grab the user's attention and enhance immersion [11].…”