36 results about "Bounding volume hierarchy" patented technology

This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for traversing a low-resolution BVH. A processor may obtain a first indication of a low-resolution BVH that includes a set of conservative candidate nodes that are associated with corresponding internal nodes of a full-resolution BVH. The processor may traverse the low-resolution BVH by (a) determining whether a ray intersects a primitive leaf of a conservative candidate node of the set of conservative candidate nodes in response to a first determination that the ray intersects the conservative candidate node and (b) traversing an internal node of the full-resolution BVH that corresponds with the conservative candidate node in response to a second determination that the ray does not intersect the primitive leaf. The processor may output a second indication of a ray trace hit or a ray trace miss based the traversal.

Techniques are disclosed relating to ray tracing, e.g., in graphics processors. Ray tracing embodiments may utilize a bounding volume hierarchy (BVH) acceleration data structure (ADS) that includes a hierarchy of bounding volumes. A graphics processor may traverse the ADS, testing for intersections with bounding volumes, to determine which primitives to test for a given ray. Some nodes may be transform nodes (e.g., instance nodes) that correspond to a ray transform before further traversal. In disclosed embodiment, one or more levels below the transform node may be reverse transformed and included above the transform node. This may advantageously avoid a ray transform operation for rays that would not have hit in the first one or more levels of the transform sub-tree.

Techniques herein involve building bounding volume hierarchies for ray tracing using neural networks. Bottom-up BVH building techniques include nearest neighbor search operations and tree construction operations. The nearest neighbor search operations evaluate a set of candidate nodes that do not have any parents to identify nearest neighbor pairs and the tree construction operations “combine” the nearest neighbor pairs by generating new nodes that are parents of the nodes of the pairs. The nearest neighbor search is an expensive operation as it generally considers all possible combinations of the set to select one considered “best.” A neural network model is thus proposed herein which can perform this nearest neighbor search in a more efficient manner. Specifically, the neural network model accepts, as input, information characterizing the nodes of a set for which a search is performed and provides, as output, information characterizing the nearest neighbor pairs found for the set.

A graphics processor includes circuitry configured to generate a bounding volume hierarchy (BVH) data structure for a graphics scene to be rendered. The BVH includes a leaf node that includes: node data that specifies quantization frame data for quantized primitive children of the leaf node, a quantized primitive block that includes quantized vertex components of the primitive children, and a vertex residual block that includes additional vertex data for the primitive children. The vertex residual block may not include redundant data with the quantized primitive block and the quantized primitive block and vertex residual block may include, for the primitive children, sufficient data to reconstruct an original-precision representation of their vertices. The circuitry may traverse the BVH to perform ray tracing operations during render of the graphics scene, including to perform one or more ray primitive intersect tests based on the quantized primitive block and the vertex residual block.

The invention relates to a method and system for constructing a ray tracing acceleration structure. A computer-implemented method of creating a bounding volume hierarchy, BVH, for a model is disclosed. The model is defined with respect to a local coordinate system of the model. The method comprises defining a BVH branch node within the model, establishing a plurality of local transformation matrices for the BVH, and for each BVH branch node, determining a first bounding volume and associating the branch node with one of the plurality of local transformation matrices that maps between the first bounding volume and a second bounding volume in the local coordinate system.

A fused bounding volume hierarchy, which is a combination of a base bounding volume hierarchy and one or more non-base bounding volume hierarchies, is generated. For each non-base bounding volume hierarchy, multiple subtrees in the non-base bounding volume hierarchy that include less than a threshold number of child nodes are identified. Each of these subtrees is then fused with the base bounding volume hierarchy at one of the nodes of the base bounding volume hierarchy, and an identifier of the level of detail for the non-base bounding volume hierarchy is included in the node. When displaying a scene or image, for a particular portion of the scene or image the level of detail to use is identified. The fused bounding volume hierarchy is traversed and the geometric objects in the nodes of the fused bounding volume hierarchy corresponding to the identified level of detail are displayed.

A technique for performing a ray tracing operation is provided. The technique includes traversing to a pre-filtering node for a tested ray intersecting a geometry associated with the bounding volume hierarchy, the pre-filtering node including information of triangles for filtering out leaf nodes of the bounding volume hierarchy; evaluating quantized rays corresponding to the rays for the quantized triangles of the pre-filtered nodes to filter out one or more triangles of the leaf nodes without consideration; and testing unfiltered triangles of the leaf nodes and not testing filtered triangles of the leaf nodes.

A technique for building a bounding volume hierarchy is disclosed. The technique includes for a subject node, selecting a dimension along which to perform a split to form child nodes of the subject node; assigning primitives of the subject node to the child nodes; and updating bounds for the child nodes in a next split dimension and not in the other dimensions.

In various examples, a supported pattern of triangles may be associated with multiple cluster templates that represent optimized triblock layouts with different levels of compression. In some embodiments, an application running on a host (e.g., a CPU) may specify an applicable compression level for a cluster of triangles or a device (e.g., a GPU) may identify one (e.g., by inspecting the vertex positions on the fly). As such, the device may look up a set of cluster templates associated with a specified pattern of triangles, identify the cluster template associated with the applicable compression level, copy that cluster template into allocated memory for the cluster, copy or transcode the vertex positions in the cluster into a precomputed triblock layout represented by the cluster template, and build a bounding volume hierarchy subtree over the cluster of triangles using a precomputed range assignment represented by the cluster template.

Techniques are disclosed relating to ray intersection tests for ray tracing in graphics processors. In some embodiments, a ray cache stores, transformed ray direction corresponding to a transform of a ray based on its dominant direction axis. Ray intersect acceleration circuitry may determine whether a ray intersects a bounding volume of a bounding volume hierarchy (BVH) data structure. Ray-plane test circuitry may perform a set of six ray-plane tests for the bounding volume using at most four floating-point multiplication operations by four multiplier circuits. The floating-point operations may operate on the transformed ray direction components from the ray cache circuitry and coordinate information for the bounding volume. Disclosed techniques may reduce area and power consumption by avoiding multiplier circuitry for some ray-plane tests.

This invention discloses a spatiotemporal data indexing query method, system, medium, and device based on GPU ray tracing, belonging to the field of spatial data indexing technology. The method includes responding to a point query request, obtaining the query coordinates, query time, and target object identifier from the point query request, emitting a vertical ray along a preset direction starting from the query coordinates and starting height, performing GPU ray traversal of the nearest intersection point on the vertical ray using a pre-established spatiotemporal index structure, and returning the intersecting geometric primitive with the smallest ray parameter, whose object identifier matches the target object identifier, and is a valid data record, as the query result of the point query request. This invention achieves hardware acceleration of spatiotemporal indexing query by uniformly mapping two-dimensional spatial coordinates and time dimension to a three-dimensional coordinate system and utilizing a bounding volume hierarchy and its corresponding geometric acceleration structure.

Data for nodes of a bounding volume hierarchy can be represented in fixed-point format for compression. For good precision, fixed-point bounds are stored along with each node, where these bounds represent the minimum and maximum representable numbers in the format. While this provides good compression, there are ways in which this technique can produce undesirable results. For example, if the size of many or most of the bounding volumes in the fixed-point number space is significantly smaller than the bounds, then the representation of such bounding volume in the fixed-point space may be unnecessarily large, resulting in a large number of false positive intersections during BVH traversal. Thus, techniques are provided herein for setting certain bounding volumes as “always hit” in order to eliminate the bounding volumes from inclusion in the fixed-point bounds. This shrinks the fixed-point bounds, giving better precision for smaller bounding volumes.

It is often desirable to perform a search for objects in a scene. Specifically, it is useful to determine whether objects are located within a search area and / or to identify the nearest objects to a search point. Ray tracing systems have capabilities that are nearly sufficient to perform such a search. For instance, ray tracing systems build acceleration structures such as bounding volume hierarchies (“BVHs”) that help to accelerate the evaluation of a ray. These BVHs are also useful for performing object searches. Ray tracing hardware includes functionality related to performing a ray-box test, which can be adapted for searching whether an object is within a search area. Ray tracing hardware also includes functionality related to instances. In ray tracing, instances are copies of geometry, with an instance transform (e.g., scale, shear, rotation) applied. As objects being searched for may be instances, the instance-related functionality is useful for object searching.

A method and apparatus for efficiently constructing a bounding volume hierarchy (BVH). For example, one embodiment of an apparatus comprises: a primitive sampler to identify a representative subset of input primitives of a graphics scene; bounding volume hierarchy (BVH) builder hardware logic to construct an approximate BVH based on the representative subset of input primitives; hardware logic to insert input primitives not in the representative subset into leaves of the approximate BVH; and the BVH builder or a different BVH builder to construct a final BVH based on the primitives inserted into the leaves of the approximate BVH.

A method performed by a graphics processor obtains a starting bounding volume hierarchy (BVH), being a data structure comprising nodes representing different 3D regions of space in a modelled environment, the data structure comprising a tree in which the nodes are arranged hierarchically from a root node down to a plurality of leaf nodes, wherein the region modelled by each leaf node encompasses at least one primitive or part of a primitive. The method further comprises performing one or more iterations, starting with a first iteration which starts with the starting BVH as a current BVH, which search for candidate reinsertions to move input nodes to new parents in the tree to reduce expected computational cost.

A processor is provided to perform a raytracing process, wherein the raytracing process includes: determining a bounding volume hierarchy (BVH) structure with leaf nodes; storing a plurality of triangles as meshlets in leaf nodes; obtaining a ray tracing acceleration data structure (RTAS) comprising BVH leaf nodes and triangles; transforming vertices of the triangles into a unit ray coordinate space; perform a culling procedure on the transformed triangles; and intersect remaining triangles with a ray in the unit ray space.

A method performed by a graphics processor searches for a candidate reinsertion for each of a plurality of input nodes of a current bounding volume hierarchy (BVH) which would move the input node from an old parent to a new parent, and which would reduce an expected computational cost of searching the BVH for a ray intersection; and performs a first update to update the current BVH with one or more selected reinsertions from among the candidates. The selection comprises a conflict check to determine whether any group of the candidates would affect a same part of the current BVH, and if so selecting only one of the group to include in the first update. At least one of the iterations further comprises, after the first update, performing a second update within the same iteration to update the current BVH with another of said group.

This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for traversing a low-resolution BVH. A processor may obtain a first indication of a low-resolution BVH that includes a set of conservative candidate nodes that are associated with corresponding internal nodes of a full-resolution BVH. The processor may traverse the low-resolution BVH by (a) determining whether a ray intersects a primitive leaf of a conservative candidate node of the set of conservative candidate nodes in response to a first determination that the ray intersects the conservative candidate node and (b) traversing an internal node of the full-resolution BVH that corresponds with the conservative candidate node in response to a second determination that the ray does not intersect the primitive leaf. The processor may output a second indication of a ray trace hit or a ray trace miss based the traversal.

This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for exploiting spatial locality to speed up first-hit ray BVH traversals. A processor may generate a bounding volume hierarchy (BVH) hit map based a set of pixels, where the BVH hit map includes entries indicative of intersection information for a set of rays associated with the set of pixels, and where the BVH hit map corresponds to a BVH. The processor may select an entry from the entries of the BVH hit map based on pixel coordinate information for the set of pixels. The processor may traverse the BVH from a node of the BVH associated with the selected entry.

A graphics processor includes circuitry configured to generate a bounding volume hierarchy (BVH) data structure for a graphics scene to be rendered. The BVH includes a leaf node that includes: quantized primitive information that includes quantized vertex components of primitive children of the leaf node and vertex residual information that includes additional vertex data, exclusive of the quantized primitive information, for the primitive children. The quantized primitive information and the vertex residual information include, for the primitive children, sufficient data to reconstruct an original-precision representation of their vertices. The circuitry may traverse the BVH to perform ray tracing operations during render of the graphics scene, including to perform one or more ray primitive intersect tests based on the quantized primitive information and the vertex residual information.

An apparatus and method for efficiently managing ray tracing to increase performance are contemplated. In various implementations, a ray tracing circuit accesses a ray tracing queue and finds pre-filtering operations. The ray tracing circuit sends a pre-filtering request to an accelerator circuit targeting quantized geometry data. The request includes an identifier of a ray origin and a ray direction, a current intersection distance, a pointer to a memory location storing bounding volume hierarchy (BVH) tree information, an identifier of a corresponding video frame, and an additional pointer or other address indicator of a memory location storing quantized pre-filter information for multiple triangles. The accelerator utilizes its larger amount of hardware resources to execute the pre-filtering operations. Afterward, the ray tracing circuit performs the ray tracing operations using non-pre-filtered geometry data of a reduced number of triangles based on results of the pre-filtering operation performed by the accelerator circuit.

Apparatus and method for asynchronous ray tracing. For example, one embodiment of a processor comprises: a bounding volume hierarchy (BVH) generator to construct a BVH comprising a plurality of hierarchically arranged nodes including a root node, a plurality of internal nodes, and a plurality of leaf nodes comprising primitives, wherein each internal node comprises a child node to either the root node or another internal node and each leaf node comprises a child node to an internal node; a first storage bank to be arranged as a first plurality of entries; a second storage bank to be arranged as a second plurality of entries, wherein each entry of the first plurality of entries and the second plurality of entries is to store a ray to be traversed through the BVH; an allocator circuit to distribute an incoming ray to either the first storage bank or the second storage bank based on a relative numbers of rays currently stored in the first and second storage banks; and traversal circuitry to alternate between selecting a next ray from the first storage bank and the second storage bank, the traversal circuitry to traverse the next ray through the BVH by reading a next BVH node from a top of a BVH node stack and determining whether the next ray intersects the next BVH node.

In order to perform ray tracing operations, a ray tracing pipeline uses one or more bounding volume hierarchies (“BVHs”) that act as an acceleration structure for accessing the geometry of a scene. In applications such as video games, simulations, or other real-time applications, geometry of the scene changes frequently such as at every frame. Thus, to have appropriate information for ray tracing, a BVH is built quite frequently. Such an operation is an expensive one. Thus, efficient techniques for BVH construction are desirable. Thus, techniques are provided herein for BVH caching BVH information. In general, these caching operations store portions of a BVH in a cache when such portions are initially encountered. Later, when that geometry is re-accessed, the caching operations search the cache for the BVH portions in the cache and uses such BVH portions if found. In some examples, the BVH cache persists between application executions.

A technique for performing ray tracing operations is provided. The technique includes for a ray being tested for intersection with geometry associated with a bounding volume hierarchy, traversing to a pre-filtering node that includes information for filtering out triangles of a leaf node of the bounding volume hierarchy; evaluating a quantized ray that corresponds to the ray against quantized triangles of the pre-filtering node to filter out one or more triangles of the leaf node from consideration; and testing the triangles of the leaf node that are not filtered out and not testing the triangles of the leaf node that are filtered out.

Apparatus and method for a hierarchical beam tracer. For example, one embodiment of an apparatus comprises: a beam generator to generate beam data associated with a beam projected into a graphics scene; a bounding volume hierarchy (BVH) generator to generate BVH data comprising a plurality of hierarchically arranged BVH nodes; a hierarchical beam-based traversal unit to determine whether the beam intersects a current BVH node and, if so, to responsively subdivide the beam into N child beams to test against the current BVH node and / or to traverse further down the BVH hierarchy to select a new BVH node, wherein the hierarchical beam-based traversal unit is to iteratively subdivide successive intersecting child beams and / or to continue to traverse down the BVH hierarchy until a leaf node is reached with which at least one final child beam is determined to intersect; the hierarchical beam-based traversal unit to generate a plurality of rays within the final child beam; and intersection hardware logic to perform intersection testing for any rays intersecting the leaf node, the intersection testing to determine intersections between the rays intersecting the leaf node and primitives bounded by the leaf node.

Techniques are disclosed relating to graphics processors that support ray tracing. In disclosed embodiments, ray intersect circuitry is configured to access a traversal stack used for traversal of multiple levels of a bounding volume hierarchy (BVH) acceleration data structure (ADS) according to a depth-first search to retrieve: coordinates of a first bounding region for a child node and a local ray parameter value that indicates a point along a ray at which an intersection with a second bounding region for the child node's parent node was detected. The accelerator circuitry may compare the local ray parameter value with an end ray parameter value to determine whether to traverse to the child node as part of traversal of the BVH.

Certain aspects and features of this disclosure relate to modeling shapes using SDF approximation. For example, a method involves partitioning a surface-bounding volume configured to contain the surface of a shape using a volumetric grid. The method also involves approximating, using a basis function, a value of a signed distance function (SDF) for samples taken inside, and on a boundary of, each surface-containing cell of the grid, and storing, based on the sign changes, coordinates for each of the cells. The method further involves constructing a surface-bounding volume hierarchy for the shape by assigning bounding volumes to each of the cells based on the coordinates. The method additionally involves determining an intersection of a ray with each surface-bounding volume in the surface-bounding volume hierarchy and rendering or storing a representation of the shape based on each intersection.

To improve the efficiency of bounding volumes in a hardware based ray tracer, we employ a sheared axis-aligned bounding box to approximate an oriented bounding box typically defined by rotations. To achieve this, the bounding volume hierarchy builder shears an axis-aligned box to fit tightly around its enclosed oriented geometry in top level or bottom level space, then computes the inverse shear transform. The bounds are still stored as axis-aligned boxes in memory, now defined in the new sheared coordinate system, along with the derived parameters to transform a ray into the sheared coordinate system before testing intersection with the boxes. The ray-bounding volume intersection test is performed as usual, just in the new sheared coordinate system. Additional efficiencies are gained by constraining the number of shear dimensions, constraining the shear transform coefficients to a quantized list, sharing a shear transform across a collection of bounds, performing a shear transform only for ray-bounds testing and not for ray-geometry intersection testing, and adding a specialized shear transform calculator / accelerator to the hardware.

A technique for building a bounding volume hierarchy is disclosed. The technique subdividing a candidate box node based on a resolution to generate a plurality of cells of the candidate box node; identifying a plurality of nodes of a triangle set collection that fit within the cells; generating a plurality of candidate splits based on the plurality of nodes; selecting a candidate split based on a selection criterion to obtain a selected candidate split; and generating child box nodes for a box node of a bounding volume hierarchy under construction, based on the selected candidate split.

A method in a graphics processor searches for a candidate reinsertion for each of a plurality of input nodes in a current bounding volume hierarchy (BVH), which would move the respective input node from an old parent to a new parent, and which would reduce the expected computational cost of searching the BVH for a ray intersection; and updates the current BVH with one or more selected reinsertions selected from among the candidates. In the search for candidate reinsertions, either or both of: a) the new parent is limited to being related to the old parent by an ancestor at no more than a predetermined number of hierarchal levels above the old parent, and / or b) the input nodes are limited to being at or above a hierarchical level a predetermined number of hierarchical levels below the root node.