We present a ray tracing algorithm that requires no explicit acceleration data structure and therefore no memory. It is represented in a completely implicit way by triangle reordering. This new implicit data structure is simple to build, efficient to traverse and has a fast total time to image. The implicit acceleration data structure must be constructed only once and can be reused for arbitrary numbers of rays or ray batches without the need to rebuild the hierarchy. Due to the fast build times it is very well suitable for dynamic and animated scenes. We compare it to classic acceleration data structures, like a Bounding Volume Hierarchy, and analyze its effciency.

We present an adaptive sampling scheme for Monte-Carlo-based renderers with the aim to support geometry-aware filtering techniques for interactive computation of global illumination. While sophisticated filtering techniques for homogeneous areas can already produce high-quality results with as few as one sample per pixel, these approaches lack the ability to filter sufficiently in the vicinity of complex geometric structures. The result are visible artifacts in the final rendering result. Our sampling scheme distributes the samples for the indirect illumination in the image plane according to the necessity of a geometry-aware filtering. We show how to implement our scheme efficiently on current graphics hardware and how to combine it with a sophisticated filtering in order to achieve high-quality interactive frame rates for global illumination simulations. The resulting computational overhead is only in the range of a few milliseconds, making our approach suitable for real-time implementations.

Interactive computation of global illumination is a major challenge in current computer graphics research. Global illumination heavily affects the visual quality of generated images. It is therefore a key attribute for the perception of photo-realistic images. Path tracing is able to simulate the physical behaviour of light using Monte Carlo techniques. However, the computational burden of this technique prohibits interactive rendering times on standard commodity hardware in high-quality. Trying to solve the Monte Carlo integration with fewer samples results in characteristic noisy images. Global illumination filtering methods take advantage of the fact that the integral for neighbouring pixels may be very similar. Averaging samples of similar characteristics in screen-space may approximate the correct integral, but may result in visible outliers. In this paper, we present a novel path tracing pipeline based on an edge-aware filtering method for the indirect illumination which produces visually more pleasing results without noticeable outliers. The key idea is not to filter the noisy path traced images but to use it as a guidance to filter a second image composed from characteristic scene attributes that do not contain noise by default. We show that our approach better approximates the Monte Carlo integral compared to previous methods. Since the computation is carried out completely in screen-space it is therefore applicable to fully dynamic scenes, arbitrary lighting and allows for high-quality path tracing at interactive frame rates on commodity hardware.

Bounding volume hierarchies (BVH) are a commonly used method for speeding up ray tracing. Even though the memory footprint of a BVH is relatively low compared to other acceleration data structures, they still can consume a large amount of memory for complex scenes and exceed the memory bounds of the host system. This can lead to a tremendous performance decrease on the order of several magnitudes. In this paper we present a novel scheme for construction and storage of BVHs that can reduce the memory consumption to less than 1% of a standard BVH. We show that our representation, which uses only 2 bits per node, is the smallest possible representation on a per node basis that does not produce empty space deadlocks. Our data structure, called the Minimal Bounding Volume Hierarchy (MVH) reduces the memory requirements in two important ways: using implicit indexing and preset surface reduction factors. Obviously, this scheme has a non-negligible computational overhead, but this overhead can be compensated to a large degree by shooting larger ray bundles instead of single rays, using a simpler intersection scheme and a two-level representation of the hierarchy. These measure enable interactive ray tracing performance without the necessity to rely on out-of-core techniques that would be inevitable for a standard BVH.

Bounding volume hierarchies have become a very popular way to speed up ray tracing. In this paper we present a novel traversal and approximation scheme for bounding volume hierarchies, which is comparable in speed, has a very compact traversal algorithm and uses only 25% of the memory, compared to a standard bounding volume hierarchy.

This paper proposes a new method for fast ray/axis-aligned bounding box overlap tests. This method tests the slope of a ray against an axisaligned bounding box by projecting itself and the box onto the three planes orthogonal to the world-coordinate axes and performs the tests on them separately. The method is division-free and successive calculations are independent of each other. No intersection distance is computed, but can be added easily. Testresults show the technique is up to 18% faster than any other method known to us and 14% faster on average for a wide variety of different test scenes and different processor architectures. Source code is available online.

Ray tracing acceleration techniques most often consider only static scenes, neglecting the processing time needed to build the acceleration data structure. With the development of interactive ray tracing systems, this reconstruction time becomes a serious bottleneck if concerned with dynamic scenes. In this paper, we describe two strategies for efficient updating of bounding volume hierarchies (BVH) for scenarios with arbitrarily moving objects. The first exploits spatial locality in the object distribution for faster reinsertion of the moved objects. The second allows insertion and deletion of objects at almost constant time by using a hybrid system, which combines benefits from both spatial subdivision and BVHs. Depending on the number of moving objects, our algorithms adjust a dynamic BVH six to one hundred times faster than it would take to rebuild the complete hierarchy, while rendering times of the resulting hierarchy remain almost untouched.