Imagination Technologies Limited

Gregory Clark

Simon James Fenney

Steven John Clohset

Rostam King

Peter Smith-Lacey

Luke Tilman Peterson

Peter Malcolm Lacey

Jeff Bond

Ilaria Martinelli

John William Howson

Justin Decell

Michael John Livesley

Daniel Barnard

Ali Rabbani

Joseph John Davison

Bruno Char

Naser Sedaghati

Mike Livesley

Jeffery Thomas Bond

Selina Hopton

Luke Peterson

Steven Clohset

A computer implemented method of building an acceleration structure for use in ray tracing includes (i) assigning, in a memory, a different one or more blocks of memory to each of a plurality of threads, each of the blocks of memory comprising one or more memory locations; (ii) for each element of a plurality of elements of a scene for which nodes of the acceleration structure are to be built, assigning that element of the scene to a block of memory so as to assign that element to a thread; and (iii) building one or more nodes of the acceleration structure by processing each of the plurality of threads in parallel.

Building an acceleration structure for use in ray tracing

A method and an intersection testing module for performing intersection testing in a ray tracing system determines a first offset intersection distance which is equal to a sum of an intersection distance at which a ray intersects a first primitive and a first offset which is dependent upon the orientation of the first primitive. A second offset intersection distance is determined which is equal to a sum of an intersection distance at which the ray intersects a second primitive and a second offset which is dependent upon the orientation of the second primitive. The determined first and second offset intersection distances are compared to select the intersection of the ray with one of the first and second primitives.

Intersection testing in a ray tracing system using offset intersection distances

A method and an intersection testing module for performing intersection testing in a ray tracing system determines that a difference between an intersection distance at which a ray intersects a first primitive and an intersection distance at which the ray intersects a second primitive satisfies a comparison condition with respect to a threshold. It is determined that the orientations of the first and second primitives are different. The intersection of the ray with one of the first and second primitives is selected on the basis that the one of the first and second primitives has a particular orientation.

Intersection testing in a ray tracing system

A system and method for coherency gathering for rays in a ray tracing system. The ray tracing system uses a hierarchical acceleration structure comprising a plurality of nodes including upper level nodes and lower level nodes. For each instance where one of the lower level nodes is a child of one of the upper level nodes, an instance transform is defined, specifying the relationship between a first coordinate system of the upper level node and the second coordinate system for that instance of the lower level node. The system provides an instance transform cache for storing a plurality of these instance transforms while conducting intersection testing.

Coherency gathering for ray tracing

A method of converting 10-bit pixel data (e.g. 10:10:10:2 data) into 8-bit pixel data involves converting the 10-bit values to 7-bits or 8-bits and generating error values for each of the converted values. Two of the 8-bit output channels comprise a combination of a converted 7-bit value and one of the bits from the fourth input channel. A third 8-bit output channel comprises the converted 8-bit value and the fourth 8-bit output channel comprises the error values. In various examples, the bits of the error values may be interleaved when they are packed into the fourth output channel.

Guaranteed data compression

A method and an intersection testing module for performing intersection testing in a ray tracing system determines if a difference between an intersection distance at which a ray intersects a first primitive and an intersection distance at which the ray intersects a second primitive satisfies a comparison condition with respect to a threshold, and if the orientations of the first and second primitives are different. If so the intersection of the ray with the one of the first and second primitives which has a particular orientation is selected.

Intersection testing in a ray tracing system using comparison of intersection distance differences between primitive intersections

A ray tracing system and method for processing data in which a forward transformation indication is received defining a transformation from a first space to a second space. A transformation is performed on input data from the second space to the first space to determine transformed data by performing a reverse translation operation on the input data, wherein the reverse translation operation is the reverse of a translation defined by the forward transformation indication. An inverse linear mapping operation is performed on the result of the reverse translation operation, wherein the inverse linear mapping operation is the inverse of a linear mapping defined by the forward transformation indication. The transformed data is processed in the ray tracing system.

Transformation of data in a ray tracing system

Methods and intersection testing modules are provided for determining, in a ray tracing system, whether a ray intersects a 3D axis-aligned box representing a volume defined by a front-facing plane and a back-facing plane for each dimension. The front-facing plane of the box which intersects the ray furthest along the ray is identified. It is determined whether the ray intersects the identified front-facing plane at a position that is no further along the ray than positions at which the ray intersects the back-facing planes in a subset of the dimensions, and this determination is used to determine whether the ray intersects the axis-aligned box. The subset of dimensions comprises the two dimensions for which the front-facing plane was not identified, but does not comprise the dimension for which the front-facing plane was identified. It is determined whether the ray intersects the box without performing a test to determine whether the ray intersects the identified front-facing plane at a position that is no further along the ray than a position at which the ray intersects the back-facing plane in the dimension for which the front-facing plane was identified.

Intersection testing in a ray tracing system using three-dimensional axis-aligned box

Ray tracing systems and methods for generating a hierarchical acceleration structure for intersection testing. Nodes of the hierarchical acceleration structure are determined, each of the nodes representing a region in a scene, the nodes being linked to form the hierarchical acceleration structure. Data is stored representing the hierarchical acceleration structure. The stored data comprises data defining the regions represented by a plurality of the nodes. At least one node is an implicitly represented node, wherein data defining a region represented by an implicitly represented node is not explicitly included as part of the stored data but can be inferred from the stored data. Also described are ray tracing systems and computer-implemented methods for performing intersection testing in which, based on conditions in the ray tracing system, a determination is made as to whether testing of one or more rays for intersection with a region represented by a particular node of a sub-tree is to be skipped.

Intersection testing in ray tracing systems with skipping of nodes in sub-trees of hierarchical acceleration structures

A ray tracing unit and method for processing a ray in a ray tracing system performs intersection testing for the ray by performing one or more intersection testing iterations. Each intersection testing iteration includes: (i) traversing an acceleration structure to identify the nearest intersection of the ray with a primitive that has not been identified as the nearest intersection in any previous intersection testing iterations for the ray; and (ii) if, based on a characteristic of the primitive, a traverse shader is to be executed in respect of the identified intersection: executing the traverse shader in respect of the identified intersection; and if the execution of the traverse shader determines that the ray does not intersect the primitive at the identified intersection, causing another intersection testing iteration to be performed. When the intersection testing for the ray is complete, an output shader is executed to process a result of the intersection testing for the ray.

A hierarchical acceleration structure for use in a ray tracing system. When generating a node for the hierarchical acceleration structure, the primitives in a particular portion of the 3D scene may be alternatively bounded by different shaped volumes. These bounding volumes or 'bounding regions' can be Axis Aligned Bounding Boxes (AABBs), although other bounding volumes can be used. The ray tracing system may use sets of two or more bounding volumes in a 3D scene to bound all the primitives within that portion. The choice of how to create sets of multiple bounding volumes within a portion of the 3D scene may be done by using a binary space partition (BSP). Different sets of bounding regions may present different amounts of surface area for a hypothetical ray entering the portion of the 3D scene dependent upon the expected ray direction or angle.

Method of traversing a hierarchical acceleration structure

A method and an intersection testing module in a ray tracing system for determining whether a ray intersects a three-dimensional axis-aligned box. It is determined whether a first condition is satisfied, wherein the first condition is, or is equivalent to, It is determined whether a second condition is satisfied, wherein the second condition is, or is equivalent to, It is determined whether a third condition is satisfied, wherein the third condition is, or is equivalent to, The determinations of whether the first, second and third conditions are satisfied are used to determine whether the ray intersects the axis-aligned box. C, Cand Care x, y and z components of a position of the centre of the axis-aligned box relative to an origin of the ray, H, Hand Hare half widths of the axis-aligned box in the x, y and z dimensions, and D, Dand Dare x, y and z components of a direction vector of the ray.

Intersection testing in a ray tracing system using axis-aligned box coordinate components

A method of data decompression includes receiving compressed pixel data substantially in raster scan order and determining a number of bits of compressed data that corresponds to one row of pixels. Then, for each group of pixels in the row, the method identifies a block-based decoding scheme for the group of pixels and decodes the group of pixels using the identified scheme.

Data decompression and packing

A method and an intersection testing module in a ray tracing system for performing intersection testing for a ray with respect to a plurality of convex polygons, each of which is defined by an ordered set of vertices. The vertices of the convex polygons are projected onto a pair of axes orthogonal to the ray direction. For each edge of a convex polygon defined by two of the projected vertices, a signed parameter is determined, wherein the sign of the signed parameter is indicative of which side of the edge the ray passes on. If the ray is determined to intersect a point on the edge then the sign of the signed parameter is determined using a module which is configured to: take as inputs, indications which classify each of p, q, pand qcoordinates as negative, zero or positive, and output, for valid combinations of classifications of the p, q, pand qcoordinates, an indication of the sign of the signed parameter. It is then determined whether the ray intersects the convex polygon based on the signs of the signed parameters determined for the edges of the convex polygon.

Intersection testing in a ray tracing system using convex polygon edge signed parameters

Ray tracing systems and methods generate a hierarchical acceleration structure to be used for intersection testing in a ray tracing system. Nodes of the hierarchical acceleration structure are determined, each representing a region in a scene, and being linked to form the hierarchical acceleration structure. Data is stored representing the hierarchical acceleration structure, including data defining the regions represented by a plurality of the nodes. At least one node is an implicitly represented node, wherein data defining a region represented by an implicitly represented node is not explicitly included as part of the stored data but can be inferred from the stored data. Intersection testing in the ray tracing system is performed in which, based on conditions in the ray tracing system, a determination is made as to whether testing of one or more rays for intersection with a region represented by a particular node of a sub-tree is to be skipped. The one or more rays are tested for intersection in accordance with the determination.

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Hemel Hempstead, United Kingdom

Gregory Clark