Microsoft Technology Licensing, LLC

Peter-Pike Johannes Sloan

Michael F Cohen

John Michael Snyder

Charles F Rose

Samuel Z Glassenberg

Craig C Peeper

Amar Dinesh Patel

Baining Guo

Yi-Ren Ng

John Lee Rapp

Daniel Kurt Baker

Michael Vincent Oneppo

Xinguo Liu

Jan Kautz

Heung-Yeung Shum

Sing Bing Kang

Xin Tong

Steven Maxwell Seitz

Xi Wang

Kun Zhou

Li-Yi Wei

Rui Wang

Zhong Ren

Ben F Luna

Bo Sun

Jesse D Hall

Methods and computer-storage media are provided for rendering three-dimensional (3D) graphics by tessellating objects using novel structures and algorithms. Rendering utilizing 'patches,' configurable functions that include a specified number of control points, allows for computation on a per-patch or per-control-point basis, in addition to traditional per-vertex, per-primitive, and per-pixel methods. This produces a number of advantages over previous tessellation methods, including the reuse of computations across existing vertices and the ability to process at a lower frequency. The operations to compute points are simplified in order to optimize system resources used in the process. Transitions from un-tessellated to tessellated objects are smoother utilizing the present invention, while developers have more flexibility in the level of detail present at different edges of the same patch. Detail within a displacement map also can be increased without negative effects associated with previous systems and methods.

Efficient geometric tessellation and displacement

In a technique for rendering non-linear BRDFs that are stable in both the temporal and spatial domains, without serious interruption to the content creation pipeline used in most games, non-linear content is linearized by rendering in texture space at a fixed resolution. A MIP-map chain is calculated from this texture. The complete MIP-map chain is used for rendering on a display device. Low resolution reflectance parameters are used to approximate the highest resolution reflectance parameters as the object becomes smaller on the display device. The low resolution reflectance parameters are calculated using non linear fitting techniques.

Shading using texture space lighting and non-linearly optimized MIP-maps

A hardware-accelerated process of computing radiance transfer coefficients (such as for use in image rendering based on precomputed radiance transfer (PRT) techniques) is re-ordered as compared to previously known PRT precomputations to iterate over a sampling of directions about an object. The hardware-accelerated process uses a set of textures representing positions and normals for a sampling of points over a modeled object. In iterating over the directions, the process computes the depth of the object in a shadow buffer, then computes a texture of the radiance contribution based on the normal and position textures and depth from the shadow buffer. The resulting radiance contribution textures of the iterated directions are accumulated to produce a texture representing the radiance transfer coefficients of the sampled positions. This enables the process to avoid reduction operations, ray tracing and slow read-back path limitations of graphical processing units.

Hardware-accelerated computation of radiance transfer coefficients in computer graphics

Encoded HDR textures are described. In one aspect, a HDR image comprised is preprocessed such that HDR information is represented in a single color channel. The preprocessed image is quantized in view of two luminance ranges to retain HDR in the single color channel. Each block of quantized channel information is then encoded across two textures (encoded HDR textures). Specifically, when encoding a block of the quantized information, pixels in a first range of the two luminance ranges are put into a color channel associated with a first texture. Additionally, pixels in a second range of the two luminance ranges are stored into a color channel associated with a second texture.

Encoded high dynamic range textures

Computer graphics image rendering techniques render images using a precomputed radiance transfer (PRT) to model local effects such as bumps, wrinkles, or other detailed features on an arbitrarily deformable model's surface. The techniques apply zonal harmonics (ZH) which approximate spherical functions as sums of circularly symmetric functions around different axes. By spatially varying both the axes and coefficients of these basis functions, approximations can fit to spatially varying transfer signals. Compared to the spherical harmonic (SH) basis, the ZH basis yields a more compact approximation, and can be rotated at a low computational expense suitable for dense per-vertex or per-pixel evaluation. This allows PRT to be mapped onto deforming models which re-orient the local coordinate frame.

Local, deformable precomputed radiance transfer

Real-time image rendering of diffuse and glossy objects in low-frequency lighting environments captures soft shadows, interreflections, and caustics. As a preprocess, a global transport simulator creates functions over the object's surface representing transfer of arbitrary, low-frequency source lighting into exiting radiance, but including global effects like shadowing and interreflection from the object onto itself. At run-time, these transfer functions are applied to the actual source lighting. Dynamic, local lighting is handled by sampling close to the object at every frame; the object can also be rigidly rotated with respect to the lighting and vice versa. Lighting and transfer functions are represented using low-order spherical harmonics. Functions for radiance transfer from a dynamic lighting environment through a preprocessed object to neighboring points in space further allow cast soft shadows and caustics from rigidly moving casters onto arbitrary, dynamic receivers.

Graphics image rendering with radiance self-transfer for low-frequency lighting environments

The present soft shadowing technique pre-computes visibility of blockers using a log of a spherical harmonic visibility function. These logs can then be accumulated and exponentiated in real-time to yield the product visibility vector over all the blockers. The product visibility vector is combined with the light intensity and surface reflectance to determine shading at a receiver point in a computer-generated scene.

Soft shadows in dynamic scenes

Shape animation is described. In one aspect, examples that pertain to a shape or motion that is to be animated are provided. The examples are placed within a multi-dimensional abstract space. Each dimension of the abstract space is defined by at least one of an adjective and an adverb. A point within the multi-dimensional abstract space is selected. The selected point does not coincide with a point that is associated with any of the examples. The selected point corresponds to a shape or motion within the abstract space. A single weight value for each of the examples is computed. The single weight values for each of the examples are combined in a manner that defines an interpolated shape or motion that is a blended combination of each of the examples of the set of examples.

Shape and animation methods and systems using examples

The present invention is directed to a enhanced Precomputed Radiance Transfer (PRT) system employing an algorithm to compute a PRT signal over a surface mesh and subdividing facets of the mesh to increase the number of surface vertices such that the spatial variation of the transfer signal is resolved sufficiently everywhere on the surface. The method of this system ensures that radiance transfer shading produces colors of sufficient accuracy all over the surface. In certain embodiments, transfer is computed only at surface vertices, although this does result in a certain amount of acceptable aliasing and blurring of surface lighting detail in regions where the tessellation is too coarse. Furthermore, the method comprises a spatial and density sampling techniques that measures the transfer signal to a desirable appropriate resolution while minimizing aliasing. Once computed, the signal is represented as compactly as possible to minimize storage and runtime computation requirements.

Systems and methods for robust sampling for real-time relighting of objects in natural lighting environments

Computer graphics systems and methods for all-frequency relighting are described. In one described embodiment, all-frequency relighting is achieved by representing low frequencies of lighting with spherical harmonics and approximating the residual high-frequency energy with point lights. In another embodiment low-frequencies are rendered with precomputed radiance transfer (PRT) techniques while the higher-frequencies are rendered with on-the-fly techniques.

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Bellevue, WA, United States of America

Peter-Pike Johannes Sloan