Applying Ray Tracing for Virtual Reality and Industrial Design

Abstract

Figure 1: Several example screenshots from the presented framework, demonstrated on a complex Mercedes C-Class model: (a) The model consists of 320,000 Bézier patches and thousands of trimming curves that are directly and interactively ray traced without triangulation.(b) The model with ray traced shaders, e.g. glass and car paint, put into a surrounding scene made up of 200,000 triangles and a captured high dynamic range environment map. Note the accurate reflections, the refraction through the glass, and the smooth shadows from environment lighting. (c) The realistic interior appearance is achieved via a shader supporting bidirectional texture functions of measured samples from the corresponding real-world materials. (d) All these effects work together seamlessly, as can be seen on this view through the side window. At slightly reduced quality during interaction, these views can be rendered at 20, 14, 1.5, and 4.8 frames per second, respectively (640 × 480 pixels). ABSTRACTComputer aided design (CAD) and virtual reality (VR) are becoming increasingly important tools for industrial design applications. Unfortunately, there is a huge and growing gap between what data CAD engineers are working on, what rendering quality is needed by designers and executives to faithfully judge a design variant, and what rendering capabilities are offered by commonly available VR frameworks. In particular, existing VR systems cannot currently cope with the accuracy demanded by CAD engineers, nor can they deliver the photo-realistic rendering quality and reliability required by designers and decision makers.In this paper, we describe a ray tracing based virtual reality framework that closes these gaps. In particular, the proposed system supports direct ray tracing of trimmed freeform surfaces even for complex models of thousands of patches, allows for accurately simulating reflections and refraction for glass and car paint effects, offers support for direct integration of measured materials via bidirectional texture functions, and even allows for soft environmental lighting from high dynamic range environment maps. All of these effects can be delivered interactively, and are demonstrated on a real-world industrial model, a complete Mercedes C-Class car.

Real-Time Global Illumination for VR Applications

“…At least 20-40 rays per pixel are needed to achieve global illumination; 7 this exceeds the ray budget we just mentioned by an order of a magnitude and will not be applicable for CAVE rendering.…”

“…The computational resources needed to solve the rendering equation numerically at real-time frame rates are currently not readily available. Popular approaches attempting this are ray tracing 7 and hierarchical finite-element approaches. 19 At the time of writing, these cannot deliver the frame rates and resolution needed for VR applications.…”

Virtual reality inspection and painting with measured BRDFs

“…Our second objective was to have an application useful in industrial and artistic design [Wald et al 2006]. We provide a new way for artists, both digital and analog, to transfer their skills to the 3D domain by painting materials directly on 3D models that they might have created or scanned from real objects.…”

Rendering techniques for mixed reality

“…The advantage of the technique is the support of local light sources. Wald et al [34] employ their interactive ray tracing system to MR rendering. While this approach delivers high quality results, a cluster of PCs is needed to perform the rendering at interactive frame rates.…”

“…While this technique is faster than path tracing, it is slower than Whitted-style ray tracing due to the additional resources needed for KD tree construction and density estimation. Wald et al [34] show that ray tracing-based techniques can produce interactive results if a cluster of PCs is used. Although the computing power of CPUs and GPUs has increased since their work, and even a first dedicated ray tracing accelerator has been developed (the Caustic One board by Caustic Graphics [4]), real-time ray tracing of complex scenes at high resolutions on a single PC is not yet possible.…”