A Computational Approach to Edge Detection
IEEE Transactions on Pattern Analysis and Machine Intelligence
Scale-Space and Edge Detection Using Anisotropic Diffusion
IEEE Transactions on Pattern Analysis and Machine Intelligence
Image selective smoothing and edge detection by nonlinear diffusion. II
SIAM Journal on Numerical Analysis
Functional optimization for fair surface design
SIGGRAPH '92 Proceedings of the 19th annual conference on Computer graphics and interactive techniques
Free-form shape design using triangulated surfaces
SIGGRAPH '94 Proceedings of the 21st annual conference on Computer graphics and interactive techniques
Computer graphics (2nd ed. in C): principles and practice
Computer graphics (2nd ed. in C): principles and practice
A comparison of normal estimation schemes
VIS '97 Proceedings of the 8th conference on Visualization '97
Design of accurate and smooth filters for function and derivative reconstruction
VVS '98 Proceedings of the 1998 IEEE symposium on Volume visualization
Implicit fairing of irregular meshes using diffusion and curvature flow
Proceedings of the 26th annual conference on Computer graphics and interactive techniques
An improved illumination model for shaded display
Communications of the ACM
A simple algorithm for surface denoising
Proceedings of the conference on Visualization '01
Geometric surface smoothing via anisotropic diffusion of normals
Proceedings of the conference on Visualization '02
Computer
Directional Representations of 4D Echocardiography for Temporal Quantification of LV Volume
MICCAI '99 Proceedings of the Second International Conference on Medical Image Computing and Computer-Assisted Intervention
A Review of Nonlinear Diffusion Filtering
SCALE-SPACE '97 Proceedings of the First International Conference on Scale-Space Theory in Computer Vision
Ocean Waves Synthesis Using a Spectrum-Based Turbulence Function
CGI '00 Proceedings of the International Conference on Computer Graphics
Transparency for computer synthesized images
SIGGRAPH '79 Proceedings of the 6th annual conference on Computer graphics and interactive techniques
Nonlinear Diffusion for Early Vision
ICPR '96 Proceedings of the 1996 International Conference on Pattern Recognition (ICPR '96) Volume I - Volume 7270
An evaluation of reconstruction filters for volume rendering
VIS '94 Proceedings of the conference on Visualization '94
Efficient and reliable schemes for nonlinear diffusion filtering
IEEE Transactions on Image Processing
IEEE Transactions on Image Processing
Spline-based gradient filters for high-quality refraction computations in discrete datasets
EUROVIS'05 Proceedings of the Seventh Joint Eurographics / IEEE VGTC conference on Visualization
Refraction in discrete ray tracing
VG'01 Proceedings of the 2001 Eurographics conference on Volume Graphics
VG'01 Proceedings of the 2001 Eurographics conference on Volume Graphics
Accelerated, high-quality refraction computations for volume graphics
VG'05 Proceedings of the Fourth Eurographics / IEEE VGTC conference on Volume Graphics
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Modeling and rendering transparent and translucent objects is one of the most important features of volume graphics. Refraction is a phenomenon closely coupled with such objects, but has largely been overlooked in volume graphics and visualization. There are two main technical difficulties. First, it is expensive to model heterogeneous refractive properties, and to incorporate refractive effects into volume rendering engines that assume light travels only along a straight line. Second, rendering refraction in volume graphics requires smoothly distributed normals to synthesize good-quality visual representations. Such refractive visualization is more susceptible to noise in the data than visualizations that do not involve refraction. In this paper, we present a comprehensive study of modeling and rendering refraction in volume graphics. In particular, we address the need for improving the continuity of voxel gradients in discretely sampled volume datasets using nonlinear diffusion methods, which were originally developed for image denoising. We consider the need for minimizing unnecessary geometrical distortion, detail the functional specification of a volumetric filter for regularized anisotropic non-linear diffusion (R-ANLD), discuss further improvements of the filter, and compare the efficacy of the filter with an anisotropic nonlinear diffusion (ANLD) filter as well as a Gaussian filter and a linear diffusion filter. Our results indicate that it is possible to make significant improvements in image quality in refractive rendering without excessive distortion. To demonstrate the practical feasibility of modeling and rendering refraction in volume graphics, we describe the implementation of refractive rendering through vlib, a volume graphics API, and discuss the parallelization of vlib in order to meet the increased demands of computational resources imposed by refractive volume rendering.