Nvidia Corporation

Mental Images Gmbh

Jacopo Pantaleoni

Shiqiu Liu

David Patrick Luebke

David Tarjan

Nan Lin

Yaobin Ouyang

Markus Kettunen

Timo Oskari Aila

Marco Salvi

Aaron Eliot Lefohn

Morgan McGuire

Christopher Ryan Wyman

Jan Novak

Michael Mara

Pascal Gautron

Eugene d″Eon

Niko Markus Kettunen

Disclosed are apparatuses, systems, and techniques to render images with global illumination using efficient ray tracing, light source identification, and reservoir resampling that deploys temporal and spatial reservoirs.

Ray tracing using reservoir resampling with spatial shift-mapping

Various approaches are disclosed to temporally and spatially filter noisy image data—generated using one or more ray-tracing effects—in a graphically rendered image. Rather than fully sampling data values using spatial filters, the data values may be sparsely sampled using filter taps within the spatial filters. To account for the sparse sampling, locations of filter taps may be jittered spatially and/or temporally. For filtering efficiency, a size of a spatial filter may be reduced when historical data values are used to temporally filter pixels. Further, data values filtered using a temporal filter may be clamped to avoid ghosting. For further filtering efficiency, a spatial filter may be applied as a separable filter in which the filtering for a filter direction may be performed over multiple iterations using reducing filter widths, decreasing the chance of visual artifacts when the spatial filter does not follow a true Gaussian distribution.

Rendering frames using jittered filter taps

Disclosed approaches provide for interactions of light transport paths in a virtual environment to share directional radiance when rendering a scene. Directional radiance that may be shared includes outgoing directional radiance of interactions, incoming directional radiance of interactions, and/or information derived therefrom. The shared directional radiance may be used for various purposes, such as computing lighting contributions at one or more interactions of a light transport path, and/or for path guiding. Directional radiance of an interaction may be shared with another interaction when the interaction is sufficiently similar (e.g., in radiance direction) to serve as an approximation of a sample for the other interaction. Sharing directional radiance may provide for online learning of directional radiance, which may build finite element approximations of light fields at the interactions.

Using directional radiance for interactions in path tracing

Disclosed approaches provide for interactions of secondary rays of light transport paths in a virtual environment to share lighting contributions when determining lighting conditions for a light transport path. Interactions may be shared based on similarities in characteristics (e.g., hit locations), which may define a region in which interactions may share lighting condition data. The region may correspond to a texel of a texture map and lighting contribution data for interactions may be accumulated to the texel spatially and/or temporally, then used to compute composite lighting contribution data that estimates radiance at an interaction. Approaches are also provided for reprojecting lighting contributions of interactions to pixels to share lighting contribution data from secondary bounces of light transport paths while avoiding potential over blurring.

Global illumination using shared lighting contributions for interactions in path tracing

This application discloses techniques for generating and querying projective hash maps. More specifically, projective hash maps can be used for spatial hashing of data related to N-dimensional points. Each point is projected onto a projection surface to convert the three-dimensional (3D) coordinates for the point to two-dimensional (2D) coordinates associated with the projection surface. Hash values based on the 2D coordinates are then used as an index to store data in the projective hash map. Utilizing the 2D coordinates rather than the 3D coordinates allows for more efficient searches to be performed to locate points in the 3D space. In particular, projective hash maps can be utilized by graphics applications for generating images, and the improved efficiency can, for example, enable a game streaming application on a server to render images transmitted to a user device via a network at faster frame rates.

Projective hash maps

Various approaches are disclosed to temporally and spatially filter noisy image data&#x2014;generated using one or more ray-tracing effects&#x2014;in a graphically rendered image. Rather than fully sampling data values using spatial filters, the data values may be sparsely sampled using filter taps within the spatial filters. To account for the sparse sampling, locations of filter taps may be jittered spatially and/or temporally. For filtering efficiency, a size of a spatial filter may be reduced when historical data values are used to temporally filter pixels. Further, data values filtered using a temporal filter may be clamped to avoid ghosting. For further filtering efficiency, a spatial filter may be applied as a separable filter in which the filtering for a filter direction may be performed over multiple iterations using reducing filter widths, decreasing the chance of visual artifacts when the spatial filter does not follow a true Gaussian distribution.

Filtering render data using multiple iterations for a filter direction

This disclosure presents a method and computer program product to denoise a ray traced scene. An apparatus for processing a ray traced scene is also disclosed. In one example, the method includes: (1) generating filtered scene data by filtering modified scene data from original scene data utilizing a spatial filter, and (2) providing a denoised ray traced scene by adjusting the filtered scene data utilizing a temporal filter. The modified and adjusted scene data can be sent to a rendering processor or system to complete rendering to generate a final scene.

Using previously rendered scene frames to reduce pixel noise

In various examples, transmittance may be computed using a power-series expansion of an exponential integral of a density function. A term of the power-series expansion may be evaluated as a combination of values of the term for different orderings of samples in the power-series expansion. A sample may be computed from a combination of values at spaced intervals along the function and a discontinuity may be compensated for based at least on determining a version of the function that includes an alignment of a first point with a second point of the function. Rather than arbitrarily or manually selecting a pivot used to expand the power-series, the pivot may be computed as an average of values of the function. The transmittance estimation may be computed from the power-series expansion using a value used to compute the pivot (for a biased estimate) or using all different values (for an unbiased estimate).

Fractional visibility estimation using particle density for light transport simulation

Temporal-spatial denoising in ray-tracing applications

This disclosure presents a method to denoise a ray traced scene where the ray tracing uses a minimal number of rays. The method can use temporal reprojections to compute a weighted average to the scene data. A spatial filter can be run on the scene data, using the temporal reprojection count to reduce the size of the utilized spatial filter radius. In some aspects, additional temporal filters can be applied to the scene data. In some aspects, global illumination temporal reprojection history counts can be used to modify the spatial filter radius. In some aspects, caustic photon tracing can be conducted to compute a logarithmic cost, which can then be utilized to reduce the denoising radius used by the spatial filter. The modified and adjusted scene data can be sent to a rendering process to complete the rendering to generate a final scene.

Techniques are disclosed for tracing a ray within a parallel processing unit. A first thread receives a ray or a ray segment for tracing and identifies a first node within an acceleration structure associated with the ray, where the first node is associated with a volume of space traversed by the ray. The thread identifies the child nodes of the first node, where each child node is associated with a different sub-volume of space, and each sub-volume is associated with a corresponding ray segment. The thread determines that two or more nodes are associated with sub-volumes of space that intersect the ray segment. The thread selects one of these nodes for processing by the first thread and another for processing by a second thread. One advantage of the disclosed technique is that the threads in a thread group perform ray tracing more efficiently in that idle time is reduced.

Fine-grained parallel traversal for ray tracing

A system, method, and computer program product are provided for tiled deferred shading. In operation, a plurality of photons associated with at least one scene are identified. Further, a plurality of screen-space tiles associated with the at least one scene are identified. Additionally, each of the plurality of screen-space tiles capable of being affected by a projection of an effect sphere for each of the plurality of photons are identified. Furthermore, at least a subset of photons associated with each of the screen-space tiles from which to compute shading are selected. Moreover, shading for the at least one scene is computed utilizing the selected at least a subset of photons.

System, method, and computer program product for tiled deferred shading

A system, method, and computer program product are provided for performing a string search. In use, a first string and a second string are identified. Additionally, a string search is performed, utilizing the first string and the second string.

Growing community of inventors

Berlin, Germany

Jacopo Pantaleoni