Abstract: 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, ? "\[LeftBracketingBar]" C x - C z ? D x D z ? "\[RightBracketingBar]" ? H z ? D x D z + H x . It is determined whether a second condition is satisfied, wherein the second condition is, or is equivalent to, ? "\[LeftBracketingBar]" C y - C z ? D y D z ? "\[RightBracketingBar]" ? H z ? D y D z + H y .

Abstract: A graphics processing system for generating a rendering output includes geometry processing logic having first transformation logic configured to transform a plurality of untransformed primitives into a plurality of transformed primitives, the first transformation logic configured to implement one or more expansion transformation stages which generate one or more sub-primitives; a primitive block generator configured to divide the plurality of transformed primitives into a plurality of groups; and generate an untransformed primitive block for each group comprising (i) information identifying the untransformed primitives related to the transformed primitives in the group; and (ii) an expansion transformation stage mask for at least one or more expansion transformation stages that indicates the sub-primitives generated for the untransformed primitives in that untransformed primitive block used in generating the rendering output.

Abstract: 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.

Abstract: Apparatus includes hardware logic arranged to normalise an n-bit input number. The hardware logic comprises at least a first hardware logic stage, an intermediate hardware logic stage and a final hardware logic stage. Each stage comprises a left shifting logic element, the first and intermediate stages each also comprise a plurality of OR-reduction logic elements and the intermediate and final stages each also comprise one or more multiplexers. The OR-reduction logic elements operate on different subsets of bits from the number input to the particular stage. In the intermediate and final hardware logic stages, a first of the multiplexers selects an OR-reduction result received from a previous hardware logic stage and the left shifting logic element is arranged to perform left shifting on the updated binary number received from an immediately previous hardware logic stage dependent upon the selected OR-reduction result.

Abstract: An image processing method and an image processing unit for performing image processing determines a set of one or more filtered pixel values, wherein the one or more filtered pixel values represent a result of processing image data using a set of one or more filtering functions. A total covariance of the set of one or more filtering functions is identified. A refinement filtering function is applied to the set of one or more filtered pixel values to determine a set of one or more refined pixel values, wherein the refinement filtering function has a covariance that is determined based on the total covariance of the set of one or more filtering functions.

Abstract: A reduced noise image can be formed from a set of images. One of the images of the set can be selected to be a reference image and other images of the set are transformed such that they are better aligned with the reference image. A measure of the alignment of each image with the reference image is determined. At least some of the transformed images can then be combined using weights which depend on the alignment of the transformed image with the reference image to thereby form the reduced noise image. By weighting the images according to their alignment with the reference image the effects of misalignment between the images in the combined image are reduced. Furthermore, motion correction may be applied to the reduced noise image.

Abstract: A plurality of work items are processed through a processing pipeline comprising a plurality of stages in processing logic. The processing of a work item includes: (i) reading data in accordance with a memory address associated with the work item, (ii) updating the read data, and (iii) writing the updated data in accordance with the memory address associated with the work item. The method includes processing a first work item and a second work item through the processing pipeline, wherein the processing of the first work item through the pipeline is initiated earlier than the processing of the second work item, and where it is determined that the first and second work items are associated with the same memory address, first updated data of the first work item is written to a register in the processing logic, and the processing of the second work item comprises reading the first updated data from the register instead of reading data from the memory.

Abstract: A texture filtering unit applies anisotropic filtering using a filter kernel which can be adapted to apply different amounts of anisotropy up to a maximum amount of anisotropy. If it is determined that a received input amount of anisotropy is not above the maximum amount of anisotropy, the filter kernel applies the input amount of anisotropy, and texels of a texture are sampled using the filter kernel to determine a filtered texture value.

Abstract: A method of rendering an image of a 3-D scene includes rendering a noisy image at a first resolution; obtaining one or more guide channels at the first resolution, and obtaining one or more corresponding guide channels at a second resolution. The second resolution may be the same resolution as, or a higher resolution than, the first resolution. For each of a plurality of local neighbourhoods, the method comprises: calculating the parameters of a model that approximates the noisy image as a function of the one or more guide channels (at the first resolution), and applying the calculated parameters to the one or more guide channels at the second resolution, to produce a denoised image at the second resolution.

Abstract: A data processing system and method are disclosed, for implementing a windowed operation in at least three traversed dimensions. The data processing system maps the windowed operation in at least three traversed dimensions to a plurality of constituent windowed operations in two traversed dimensions. This plurality of 2-D windowed operations is implemented as such in at least one hardware accelerator. The data processing system assembles the results of the constituent 2-D windowed operations to produce the result of the windowed operation in at least three traversed dimensions.

Abstract: Methods and systems for verifying a hardware design for an integrated circuit that implements a function that is polynomial in an input variable x over a set of values of x. The method includes formally verifying that a first instantiation of the hardware design implements a function that is polynomial of degree k in x by formally verifying that for all x in the set of values of x the first instantiation of the hardware design has a constant kth difference; and verifying that a second instantiation of the hardware design generates an expected output in response to each of at least k different values of x in the set of values of x.

Abstract: 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.

Abstract: Methods and systems for verifying a hardware design for an integrated circuit that implements a function that is polynomial of degree k in a sub-function p over a set of values of p, k being an integer greater than or equal to one. The methods include: verifying that an instantiation of the hardware design correctly evaluates the sub-function p; formally verifying that an instantiation of the hardware design implements a function that is polynomial of degree k in p by formally verifying that, for all values of p in the set of values of p, an instantiation of the hardware design has a constant kth difference; and verifying that an instantiation of the hardware design generates an expected output in response to each of at least e different values of p in the set of values of p, wherein e is equal to k when a value of the kth difference is predetermined and e is equal to k+1 when the value of the kth difference is not predetermined.

Abstract: Texture filtering in computer graphics calculates first and second pairs of texture-space basis vectors that correspond to first and second pairs of screen-space basis vectors transformed to texture space under a local approximation of a mapping between screen space and texture space. Based on differences in magnitudes of the vectors of the pairs of texture-space basis vectors, an angular displacement is determined between a selected pair of the first and second pairs of screen-space basis vectors and screen-space principal axes of the local approximation of the mapping that indicate maximum and minimum scale factors of the mapping. The determined angular displacement and the selected pair of screen-space basis vectors are used to generate texture-space principal axes, with a major axis associated with the maximum scale factor of the mapping and a minor axis associated with the minimum scale factor of the mapping. A texture is filtered using the major and minor axes.

Abstract: A graphics processing hardware pipeline is arranged to perform an edge test or a depth calculation. Each hardware arrangement includes a microtile component hardware element, multiple pixel component hardware elements, one or more subsample component hardware elements and a final addition and comparison unit. The microtile component hardware element calculates a first output using a sum-of-products and coordinates of a microtile within a tile in the rendering space. Each pixel component hardware element calculates a different second output using the sum-of-products and coordinates for different pixels defined relative to an origin of the microtile. The subsample component hardware element calculates a third output using the sum-of-products and coordinates for a subsample position defined relative to an origin of a pixel.

Abstract: A method and apparatus are provided for tessellating patches of surfaces in a tile based three dimensional computer graphics rendering system. For each tile in an image a per tile list of primitive indices is derived for tessellated primitives which make up a patch. Hidden surface removal is then performed on the patch and any domain points which remain after hidden surface removal are derived. The primitives are then shaded for display.

Abstract: A method of processing rays in a ray tracing system, the method comprising: allocating a block of memory for a task on a per-task basis; processing rays in the task causing at least one child ray to be emitted; writing intermediate data for the task to said block of memory; suspending processing of the task; and when the task is ready to resume, reading intermediate data for the task from the block of memory, and resuming the processing of the task.

Abstract: Interpolation logic described herein provides a good approximation to a bicubic interpolation, which is generally smoother than bilinear interpolation, without performing all the calculations normally needed for a bicubic interpolation. This allows an approximation of smooth bicubic interpolation to be performed on devices (e.g. mobile devices) which have limited processing resources. At each of a set of predetermined interpolation positions within an array of data points, a set of predetermined weights represent a bicubic interpolation which can be applied to the data points. For a plurality of the predetermined interpolation positions which surround the sampling position, the corresponding sets of predetermined weights and the data points are used to determine a plurality of surrounding interpolated values which represent results of performing the bicubic interpolation at the surrounding predetermined interpolation positions.

Abstract: A computer system includes a physical memory having a first page table and a second page table, and an address translation module. The first page table includes primary page table entries, where each page table entry among the primary page table entries is configured to store a mapping of a virtual memory address to a physical memory address and auxiliary information. The second page table includes secondary page table entries each storing at least one further auxiliary information, where each secondary page table entry corresponds to a primary page table entry in the first page table. The address translation module is configured to, in response to receiving a request from a processor, walk through the first page table to identify a primary page table entry and consecutively identify a location of a corresponding secondary page table entry based on a location of the primary page table entry.

Abstract: Texture filtering is applied to a texture represented with a mipmap comprising a plurality of levels, wherein each level of the mipmap comprises an image representing the texture at a respective level of detail. A texture filtering unit has minimum and maximum limits on an amount by which it can alter the level of detail when it filters texels from an image of a single level of the mipmap. The range of level of detail between the minimum and maximum limits defines an intrinsic region of the texture filtering unit. If it is determined that a received input level of detail is in an intrinsic region of the texture filtering unit, texels are read from a single mipmap level of the mipmap, and the read texels from the single mipmap level are filtered to determine a filtered texture value representing part of the texture at the input level of detail.