Imagination Technologies Limited

Caustic Graphics, Inc.

Luke Tilman Peterson

James Alexander McCombe

Steven John Clohset

Ryan R Salsbury

Jason Rupert Redgrave

John William Howson

Jens Fursund

Cuneyt Ozdas

Justin P DeCell

Stephen C Purcell

Sean Matthew Gies

Aaron Dwyer

Joseph M Richards

Gregory Clark

Steven Blackmon

Simon James Fenney

Justin Decell

Gareth Morgan

Neils Nesse

James A Mccombe

James Jones

Stephen John Clohset

Matthew Harrison

Ali Rabbani

Naser Sedaghati

A light map for a scene is determined for use in rendering the scene in a graphics processing system. Initial lighting indications representing lighting within the scene are determined. For a texel position of the light map, the initial lighting indications are sampled using an importance sampling technique to identify positions within the scene. Sampling rays are traced between a position in the scene corresponding to the texel position of the bounce light map and the respective identified positions with the scene. A lighting value is determined for the texel position of the light map using results of the tracing of the sampling rays. By using the importance sampling method described herein, the rays which are traced are more likely to be directed towards more important regions of the scene which contribute more to the lighting of a texel.

Importance sampling for determining a light map

A hierarchy is a multi-level linked structure of nodes, wherein the hierarchy represents data relating to a set of one or more items to be processed. Where there are multiple input hierarchies, it may improve the efficiency of the processing of the items to merge the input hierarchies to form a merged hierarchy. The hierarchies are merged by identifying two or more sub-hierarchies within the input hierarchies which are to be merged, and determining one or more nodes of the merged hierarchy which reference nodes of the identified sub-hierarchies. The determined nodes of the merged hierarchy are stored and indications of the references between the determined nodes of the merged hierarchy and the referenced nodes of the identified sub-hierarchies are also stored. In this way, the merged hierarchy is formed for use in processing the items.

Hierarchy merging in computer graphics

Systems and methods for producing an acceleration structure provide for subdividing a 3-D scene into a plurality of volumetric portions, which have different sizes, each being addressable using a multipart address indicating a location and a relative size of each volumetric portion. A stream of primitives is processed by characterizing each according to one or more criteria, selecting a relative size of volumetric portions for use in bounding the primitive, and finding a set of volumetric portions of that relative size which bound the primitive. A primitive ID is stored in each location of a cache associated with each volumetric portion of the set of volumetric portions. A cache location is selected for eviction, responsive to each cache eviction decision made during the processing. An element of an acceleration structure according to the contents of the evicted cache location is generated, responsive to the evicted cache location.

Systems and methods for 3-D scene acceleration structure creation and updating

Rendering system combines point sampling and volume sampling operations to produce rendering outputs. For example, to determine color information for a surface location in a 3-D scene, one or more point sampling operations are conducted in a volume around the surface location, and one or more sampling operations of volumetric light transport data are performed farther from the surface location. A transition zone between point sampling and volume sampling can be provided, in which both point and volume sampling operations are conducted. Data obtained from point and volume sampling operations can be blended in determining color information for the surface location. For example, point samples are obtained by tracing a ray for each point sample, to identify an intersection between another surface and the ray, to be shaded, and volume samples are obtained from a nested 3-D grids of volume elements expressing light transport data at different levels of granularity.

Determining lighting information for rendering a scene in computer graphics using illumination point sampling

Graphics processing system configured to perform ray tracing. Rays are bundled together and processed together. When differential data is needed by a shader, the data of a true ray in the bundle can be used rather than processing separate tracker rays.

Methods and graphics processing units for determining differential data for rays of a ray bundle

Graphics processing systems can include lighting effects when rendering images. 'Light probes' are directional representations of lighting at particular probe positions in the space of a scene which is being rendered. Light probes can be determined iteratively, which can allow them to be determined dynamically, in real-time over a sequence of frames. Once the light probes have been determined for a frame then the lighting at a pixel can be determined based on the lighting at the nearby light probe positions. Pixels can then be shaded based on the lighting determined for the pixel positions.

Graphics processing using directional representations of lighting at probe positions within a scene

Ray tracing units, processing modules and methods are described for generating one or more reduced acceleration structures to be used for intersection testing in a ray tracing system for processing a 3D scene. Nodes of the reduced acceleration structure(s) are determined, wherein a reduced acceleration structure represents a subset of the 3D scene. The reduced acceleration structure(s) are stored for use in intersection testing. Since the reduced acceleration structures represent a subset of the scene (rather than the whole scene) the memory usage for storing the acceleration structure is reduced, and the latency in the traversal of the acceleration structure is reduced.

Reduced acceleration structures for ray tracing systems

In some aspects, finer grained parallelism is achieved by segmenting programmatic workloads into smaller discretized portions, where a first element can be indicative both of a configuration or program to be executed, and a first data set to be used in such execution, while a second element can be indicative of a second data element or group. The discretized portions can cause program execute on distributed processors. Approaches to selecting processors, and allocating local memory associated with those processors are disclosed. In one example, discretized portions that share a program have an anti-affinity to cause dispersion, for initial execution assignment. Flags, such as programmer and compiler generated flags can be used in determining such allocations. Workloads can be grouped according to compatibility of memory usage requirements.

Scheduling computation tasks for execution by multiple processing units using computation task profiling

In some aspects, systems and methods provide for forming groupings of a plurality of independently-specified computation workloads, such as graphics processing workloads, and in a specific example, ray tracing workloads. The workloads include a scheduling key, which is one basis on which the groupings can be formed. Workloads grouped together can all execute from the same source of instructions, on one or more different private data elements. Such workloads can recursively instantiate other workloads that reference the same private data elements. In some examples, the scheduling key can be used to identify a data element to be used by all the workloads of a grouping. Memory conflicts to private data elements are handled through scheduling of non-conflicted workloads or specific instructions and/or deferring conflicted workloads instead of locking memory locations.

Graphics processor with non-blocking concurrent architecture

Ray tracing, and more generally, graphics operations taking place in a 3-D scene, involve a plurality of constituent graphics operations. Responsibility for executing these operations can be distributed among different sets of computation units. The sets of computation units each can execute a set of instructions on a parallelized set of input data elements and produce results. These results can be that the data elements can be categorized into different subsets, where each subset requires different processing as a next step. The data elements of these different subsets can be coalesced so that they are contiguous in a results set. The results set can be used to schedule additional computation, and if there are empty locations of a scheduling vector (after accounting for the members of a given subset), then those empty locations can be filled with other data elements that require the same further processing as that subset.

Ray tracing in computer graphics using intersection testing at selective resolution

Aspects relate to tracing rays in 3-D scenes that comprise objects that are defined by or with implicit geometry. In an example, a trapping element defines a portion of 3-D space in which implicit geometry exist. When a ray is found to intersect a trapping element, a trapping element procedure is executed. The trapping element procedure may comprise marching a ray through a 3-D volume and evaluating a function that defines the implicit geometry for each current 3-D position of the ray. An intersection detected with the implicit geometry may be found concurrently with intersections for the same ray with explicitly-defined geometry, and data describing these intersections may be stored with the ray and resolved.

3-D graphics rendering with implicit geometry

Aspects include a multistage collector to receive outputs from plural processing elements. Processing elements may comprise (each or collectively) a plurality of clusters, with one or more ALUs that may perform SIMD operations on a data vector and produce outputs according to the instruction stream being used to configure the ALU(s). The multistage collector includes substituent components each with at least one input queue, a memory, a packing unit, and an output queue; these components can be sized to process groups of input elements of a given size, and can have multiple input queues and a single output queue. Some components couple to receive outputs from the ALUs and others receive outputs from other components. Ultimately, the multistage collector can output groupings of input elements. Each grouping of elements (e.g., at input queues, or stored in the memories of component) can be formed based on matching of index elements.

Multistage collector for outputs in multiprocessor systems

Graphics processing systems and methods provide soft shadowing effects into rendered images. This is achieved in a simple manner which can be implemented in real-time without incurring high processing costs so it is suitable for implementation in low-cost devices. Rays are cast from positions on visible surfaces corresponding to pixel positions towards the center of a light, and occlusions of the rays are determined. The results of these determinations are used to apply soft shadows to the rendered pixel values.

Systems and methods for soft shadowing in 3-D rendering casting multiple rays from ray origins

Systems and methods of geometry processing, for rasterization and ray tracing processes provide for pre-processing of source geometry, such as by tessellating or other procedural modification of source geometry, to produce final geometry on which a rendering will be based. An acceleration structure (or portion thereof) for use during ray tracing is defined based on the final geometry. Only coarse-grained elements of the acceleration structure may be produced or retained, and a fine-grained structure within a particular coarse-grained element may be Produced in response to a collection of rays being ready for traversal within the coarse grained element. Final geometry can be recreated in response to demand from a rasterization engine, and from ray intersection units that require such geometry for intersection testing with primitives. Geometry at different resolutions can be generated to respond to demands from different rendering components.

On demand geometry and acceleration structure creation with tile object lists

Aspects comprise systems implementing 3-D graphics processing functionality in a multiprocessing system. Control flow structures are used in scheduling instances of computation in the multiprocessing system, where different points in the control flow structure serve as points where deferral of some instances of computation can be performed in favor of scheduling other instances of computation. In some examples, the control flow structure identifies particular tasks, such as intersection testing of a particular portion of an acceleration structure, and a particular element of shading code. In some examples, the aspects are used in 3-D graphics processing systems that can perform ray tracing based rendering.

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San Francisco, CA, United States of America

Luke Tilman Peterson