Existing techniques for rendering arbitrary-form implicit surfaces are limited, either in performance, correctness or flexibility. Ray tracing algorithms employing interval arithmetic (IA) or affine arithmetic (AA) for root-finding are robust and general in the class of surfaces they support, but traditionally slow. Nonetheless, implemented efficiently using a stack-driven iterative algorithm and SIMD vector instructions, these methods can achieve interactive performance for common algebraic surfaces on the CPU. A similar algorithm can also be implemented stacklessly, allowing for efficient ray tracing on the GPU. This paper presents these algorithms, as well as an inclusion-preserving reduced affine arithmetic (RAA) for faster ray-surface intersection. Shader metaprogramming allows for immediate and automatic generation of symbolic expressions and their interval or affine extensions. Moreover, we are able to render even complex forms robustly, in real-time at high resolution.

with depth cues (Depth Darkening [24] and fogging). Right: Surface colored according to the temperature factor of the protein with silhouettes. Abstract—Molecular dynamics simulations of proteins play a growing role in various fields such as pharmaceutical, biochemical and medical research. Accordingly, the need for high quality visualization of these protein systems raises. Highly interactive visualization techniques are especially needed for the analysis of time-dependent molecular simulations. Beside various other molecular representations the surface representations are of high importance for these applications. So far, users had to accept a trade-off between rendering quality and performance—particularly when visualizing trajectories of time-dependent protein data. We present a new approach for visualizing the Solvent Excluded Surface of proteins using a GPU ray casting technique and thus achieving interactive frame rates even for long protein trajectories where conventional methods based on precomputation are not applicable. Furthermore, we propose a semantic simplification of the raw protein data to reduce the visual complexity of the surface and thereby accelerate the rendering without impeding perception of the protein’s basic shape. We also demonstrate the application of our Solvent Excluded Surface method to visualize the spatial probability density for the protein atoms over the whole period of the trajectory in one frame, providing a qualitative analysis of the protein flexibility.

Interactive visualization of massive models still remains a challenging problem. This is mainly due to a combination of ever increasing model complexity with the current hardware design trend that leads to a widening gap between slow data access speed and fast data processing speed. We argue that developing efficient data access and data management techniques is key in solving the problem of interactive visualization of massive models. Particularly, we discuss visibility culling, simplification, cache-coherent layouts, and data compression techniques as efficient data management techniques that enable interactive visualization of massive models.

Existing methods for rendering arbitrary implicit functions are limited, either in performance, correctness or flexibility. Ray tracing methods in conjunction with an inclusion algebra such as interval arithmetic (IA) or affine arithmetic (AA) have historically proven robust and flexible, but slow. In this paper, we present a new stackless ray traversal algorithm optimized for modern graphics hardware, and a correct inclusion-preserving reduced affine arithmetic (RAA) suitable for fragment shader languages. Shader metaprogramming allows for immediate and automatic generation of functions and their interval or affine extensions, enhancing user interaction. Ray tracing lends itself to multi-bounce effects, such as shadows and depth peeling, which are useful modalities for visualizing complicated implicit functions. With this system, we are able to render even complex implicits correctly, in real-time at high resolution. 1

c t i v it y e p o r t 2009 Table of contents

c t i v it y e p o r t

Abstract. We present a method to interactively visualize large industrial models by replacing most triangles with implicit GPU primitives: cylinders, cone and torus slices. After a reverse-engineering process that recovers these primitives from triangle meshes, we encode their implicit parameters in a texture that is sent to the GPU. In rendering time, the implicit primitives are visualized seamlessly with other triangles in the scene. The method was tested on two massive industrial models, achieving better performance and image quality while reducing memory use. 1