Nvidia Corporation

Mental Images Gmbh

Carsten Alexander Waechter

Alexander Georg Keller

Nikolaus Binder

Lutz Kettner

Pascal Gautron

Matthias Raab

Samuli Matias Laine

Timo Oskari Aila

Tero Tapani Karras

Jaakko Tapani Lehtinen

Marc Droske

Ken Dahm

Daniel Seibert

Stefan Radig

Dietger Van Antwerpen

Dirk Gerrit Van Antwerpen

In photorealistic image synthesis by light transport simulation, the colors of each pixel are an integral of a high-dimensional function. However, the functions to integrate contain discontinuities that cannot be predicted efficiently. In practice, the pixel colors are estimated by using Monte Carlo and quasi-Monte Carlo methods to sample light transport paths that connect light sources and cameras and summing up the contributions to evaluate an integral. Because of the sampling, images appear noisy when the number of samples is insufficient. A low discrepancy sequence provides sample locations and these sample locations can be enumerated (assigned or distributed to pixels) according to a space-filling curve superimposed on a pixel grid. Correlations of such combinations of space-filling curves and low discrepancy sequences are analyzed, and the presented algorithms reduce correlations, are deterministic, and may be executed for each pixel in parallel.

Rendering along a space-filling curve

Approaches presented herein reduce the presence of temporary artifacts such, as flickering, when using spatial hashing with simulation. Flickering can be avoided, at least in part, by ensuring that the same simulation points are utilized in separate executions of an algorithm, even where the execution order can vary. This can involve selecting a single representative point for each hash cell of a spatial hash map, where simulation for that hash cell will be performed for that representative point location, regardless of execution order. Both a location index and a selector value are stored for this hash map entry in a single value, where lower bits store the location index and higher bits represent the selector value. Storing the selector value in the higher-weight bits ensures an atomic maximum operation will primarily consider the selector value, and resort to the location index only in the event of equal selector values.

Consistent sampling for spatial hashing

Systems and methods to implement a technique for determining an environment importance sampling function. An environment map may be provided where lighting information about the environment is known, but where certain pixels within a scene associated with the environment map are shaded. From these shaded pixels, rays may be drawn in random directions to determine whether the rays are occluded or can interact with the environment map, which provides an indication of a source of lighting that can be used for light transport simulations. A mask may be generated based on these occlusions and used to update the environment importance sampling function.

Visibility-based environment importance sampling for light transport simulation systems and applications

An apparatus, computer readable medium, and method are disclosed for decompressing compressed geometric data stored in a lossless compression format. The compressed geometric data resides within a compression block sized according to a system cache line. An indirection technique maps a global identifier value in a linear identifier space to corresponding variable rate compressed data. The apparatus may include decompression circuitry within a graphics processing unit configured to perform ray-tracing.

Block-based lossless compression of geometric data

A method of adjusting a shading normal vector for a computer graphics rendering program. Calculating a normalized shading normal vector pointing outwards from an origin point on a tessellated surface modeling a target surface to be rendered. Calculating a normalized outgoing reflection vector projecting from the origin point for an incoming view vector directed towards the origin point and reflecting relative to the normalized shading normal vector. Calculating a correction vector such that when the correction vector is added to the normalized outgoing reflection vector a resulting vector sum is yielded that is equal to a maximum reflection vector, wherein the maximum reflection vector is on or above the tessellated surface. Calculating a normalized maximum reflection vector by normalizing a vector sum of the correction vector plus the maximum reflection vector. Calculating a normalized adjusted shading normal vector by normalizing a vector difference of the normalized maximum reflection vector minus the incoming view vector.

View-dependant shading normal adaptation

A method and renderer for a progressive computation of a light transport simulation are provided. The method includes the steps of employing a low discrepancy sequence of samples; and scrambling an index of the low discrepancy sequence independently per region using a hash value based on coordinates of a respective region, wherein for each set of a power-of-two number of the samples, the scrambling is a permutation.

Decorrelation of low discrepancy sequences for progressive rendering

A method, system, and computer program product for performing a lighting simulation are disclosed. The method includes the steps of receiving a three-dimensional (3D) model, receiving a set of probes, where each probe specifies a location within the 3D model and an orientation of the probe, and performing, via a processor, a lighting simulation based on the 3D model, the set of probes, and one or more light path expressions. The light path expressions are regular expressions that represent a series of events, each event representing an interaction of a ray at a location in the 3D model.

Lighting simulation analysis using light path expressions

A system, method, and computer program product are provided for determining a quantity of light received by an element of a scene. In use, a quantity of light received by a first element of the scene is determined by averaging a quantity of light received by elements of the scene that are associated with a selected set of light paths.

System, method, and computer program product for determining a quantity of light received by an element of a scene

Methods, systems and computer program code (software) products executable in a digital processor operable to simulate light transport in a scene by ray tracing (wherein the digital processor is operable to maintain an object list representing a list of objects associated with a boundary of the scene) include executing a ray tracing method that traces r rays through n objects by (1) partitioning the object list in a recursive manner to generate partitions and (2) culling away the partitions of objects from rays, without using an explicit auxiliary acceleration data structure.

Efficient ray tracing without acceleration data structure

Methods, systems, devices and computer program code (software) products operable within a computer graphics system or other computer system enable quasi-Monte Carlo (QMC) light transport simulation by ray tracing: and include constructing a bounding interval hierarchy (BIH), within a computer, using quantized planes to reduce memory requirements while maintaining a selected degree of precision.

Quasi-monte carlo light transport simulation by efficient ray tracing

Methods, systems, apparatus and computer software/computer code products operable to enable computer graphics systems to simulate Markov chains (and thus trajectories of photons and the like) comprise simulating, and/or means for simulating, Markov chains using a quasi-Monte Carlo methodology, wherein the simulating of Markov chains comprises sorting states, and wherein the sorting comprises proximity sorting.

Simultaneous simulation of markov chains using quasi-monte carlo techniques

The present invention provides methods, systems and computer program code (software) products for terminating spatial partition hierarchies and other hierarchies by a priori bounding.

Terminating spatial partition hierarchies by a priori bounding memory

Systems and techniques are described for ray tracing and for the efficient construction of acceleration data structures required for fast ray tracing. A computer graphics system generates, for each pixel in an image, a pixel value that is representative of a point in a scene as recorded on an image plane of a simulated camera. The computer graphics system is configured to generate the pixel value for an image using a selected ray-tracing methodology. The selected ray-tracing methodology includes the use of a ray tree that includes at least one ray shot from the pixel into a scene along a selected direction. The ray-tracing methodology further includes calculating the intersections of rays and surfaces in the scene. An axis-aligned bounding box is defined that contains, for a given ray, the point of intersection of the ray and surface nearest the origin of the ray. The bounding box is iteratively refined until a predetermined termination criterion has been met.

Real-time precision ray tracing

Methods, systems, devices and computer program products operable in a computer graphics system include constructing a hierarchical ray tracing acceleration data structure comprising a tree structure, the nodes of which are generated utilizing a bounding interval hierarchy based on defining an axis-aligned scene bounding box and two parallel planes to partition a set of objects in a sense into left objects and right objects, and matching split planes to object bounding boxes. The two planes are perpendicular to a selected one of x, y, or z-axes. Given a splitting plane, each object in an image is classified either left or right based on a left/right selection criterion, and two splitting plane values of the child modes are determined by the maximum and minimum coordinate of the left and right objects, respectively.

Growing community of inventors

Berlin, Germany

Carsten Alexander Waechter