公开(公告)号：US20050104883A1

公开(公告)日：2005-05-19

申请号：US10951272

申请日：2004-09-27

申请人： John Snyder ,  Peter-Pike Sloan ,  Xinguo Liu ,  Heung-Yeung Shum

发明人： John Snyder ,  Peter-Pike Sloan ,  Xinguo Liu ,  Heung-Yeung Shum

IPC分类号： G06T15/50 ,  G06T15/60

CPC分类号： G06T15/50

摘要： The described systems and methods are directed at interactively rendering graphics using precomputed radiance transfer (PRT). A reflectance matrix that represents the reflectance of a particular object to be rendered is determined. Source lighting associated with the object is represented using basis functions. The reflectance matrix is factored into view and light components. A raw transfer matrix is determined based, in part, from the factored reflectance matrix and the source lighting. The raw transfer matrix is partitioned to obtain transfer matrices, which are used to render the object. The described systems and methods are capable of rendering glossy objects with well-defined shadows.

摘要翻译： 所描述的系统和方法针对使用预计算辐射传输（PRT）的交互式渲染图形。 确定表示要呈现的特定对象的反射率的反射率矩阵。 使用基础函数表示与对象相关联的源照明。 反射率矩阵被考虑到视图和光分量中。 原始转移矩阵部分地基于因子反射矩阵和源照明来确定。 原始传输矩阵被分割以获得用于渲染对象的传输矩阵。 所描述的系统和方法能够渲染具有明确定义阴影的光泽对象。

公开(公告)号：US20050083340A1

公开(公告)日：2005-04-21

申请号：US10687098

申请日：2003-10-15

申请人： Peter-Pike Sloan ,  John Snyder ,  Xinguo Liu ,  Heung-Yeung Shum

发明人： Peter-Pike Sloan ,  John Snyder ,  Xinguo Liu ,  Heung-Yeung Shum

IPC分类号： G06T15/50 ,  G09G5/00

CPC分类号： G06T15/60 ,  G06T15/506

摘要： Computer graphics image rendering techniques render images modeling transfer at two scales. A macro-scale is coarsely sampled over an object's surface, providing global effects like shadows and interreflections cast from an arm onto a body. A meso-scale is finely sampled over a small patch to provide local texture. Low-order spherical harmonics represent low-frequency lighting dependence for both scales. To render, a coefficient vector representing distant source lighting is first transformed at the macro-scale by a matrix at each vertex of a coarse mesh, resulting in vectors representing a spatially-varying hemisphere of lighting incident to the meso-scale. A radiance transfer texture specifies the meso-scale response to each lighting basis component, and a function of a spatial index and a view direction. A dot product of the macro-scale result vector with the vector looked up from the radiance transfer texture performs the correct shading integral. An id map places radiance transfer texture samples from a small patch over the object's surface, so that only two scalars are specified at high spatial resolution.

摘要翻译： 计算机图形图像渲染技术在两个尺度上渲染图像建模传输。 宏观尺度在对象的表面上粗略采样，提供全局效果，如阴影和从臂上投射到身体上的反射。 在小贴片上精细采样中尺度以提供局部纹理。 低阶球面谐波代表两种尺度的低频照明依赖性。 为了渲染，首先通过在粗网格的每个顶点处的矩阵在宏观尺度上变换表示远距离源照明的系数矢量，导致表示入射到中尺度的照明的空间变化的半球的矢量。 辐射传递纹理指定对每个照明基础部分的中尺度响应，以及空间索引和视图方向的函数。 宏观尺度结果向量与从辐射传递纹理查找的向量的点积执行正确的阴影积分。 id映射将辐射传递纹理样本从对象表面上的小补丁传递，以便在高空间分辨率下仅指定两个标量。

公开(公告)号：US20060290693A1

公开(公告)日：2006-12-28

申请号：US11158428

申请日：2005-06-22

申请人： Kun Zhou ,  John Snyder ,  Xinguo Liu ,  Baining Guo ,  Heung-Yeung Shum

发明人： Kun Zhou ,  John Snyder ,  Xinguo Liu ,  Baining Guo ,  Heung-Yeung Shum

IPC分类号： G06T17/00 ,  G06T17/20 ,  G06T15/30

CPC分类号： G06T17/20 ,  G06T13/20

摘要： Large mesh deformation using the volumetric graph Laplacian is described. In one aspect, information is received from a user, wherein the information indicates how an original mesh is to be deformed. The original mesh is then deformed based on the information and application of a volumetric differential operator to a volumetric graph generated from the original mesh.

摘要翻译： 描述了使用体积图拉普拉斯算子的大网格变形。 在一个方面，从用户接收信息，其中信息指示原始网格如何变形。 然后将原始网格基于体积差分算子的信息和应用变形为从原始网格生成的体积图。

公开(公告)号：US20070247472A1

公开(公告)日：2007-10-25

申请号：US11277938

申请日：2006-03-29

申请人： Xin Tong ,  Yanyun Chen ,  Baining Guo ,  Heung-Yeung Shum ,  Jiaping Wang ,  John Snyder

发明人： Xin Tong ,  Yanyun Chen ,  Baining Guo ,  Heung-Yeung Shum ,  Jiaping Wang ,  John Snyder

IPC分类号： G09G5/00

CPC分类号： G01B11/24 ,  G01S17/89 ,  G06T15/04

摘要： A method and system for implementing capturing and rendering geometric details for mesostructure surfaces is described herein. A mesostructure distance function is defined as a function of a given reference point and a given viewing direction. A distance from a reference point to a mesostructure surface point along a viewing direction is measured using the mesostructure distance function. This distance is used to determine the visibility of mesostructure surface for rendering silhouettes. The lighting visibility of the mesostructure surface point may also be determined and used for determining whether the mesostructure surface point is in shadow. This determination may then be used for rendering shadow silhouettes.

摘要翻译： 本文描述了一种用于实现用于介观结构表面的捕获和渲染几何细节的方法和系统。 介观结构距离函数被定义为给定参考点和给定观察方向的函数。 使用介观结构距离函数测量从参考点到观察方向的介观结构表面点的距离。 该距离用于确定用于渲染轮廓的介观结构表面的可见性。 也可以确定介观结构表面点的照明可见度，并用于确定介观结构表面点是否处于阴影。 然后可以将该确定用于渲染阴影剪影。

公开(公告)号：US20050078116A1

公开(公告)日：2005-04-14

申请号：US10815141

申请日：2004-03-31

申请人： Peter-Pike Sloan ,  Yi-Ren Ng ,  John Snyder

发明人： Peter-Pike Sloan ,  Yi-Ren Ng ,  John Snyder

IPC分类号： F21V9/00 ,  G06F15/16

CPC分类号： G06T15/55 ,  G06T15/50

摘要： 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.

摘要翻译： 本发明涉及一种增强的预计算辐射传输（PRT）系统，该系统采用一种算法来在表面网格上计算PRT信号并细分网格面，以增加表面顶点的数量，使得传输信号的空间变化为 在表面上的任何地方充分解决。 该系统的方法确保辐射传递阴影在整个表面上产生足够精确的颜色。 在某些实施例中，仅在表面顶点处计算传输，尽管这确实导致在细分太粗糙的区域中的一定量的可接受的混叠和模糊表面照明细节。 此外，该方法包括空间和密度采样技术，其将传输信号测量到期望的适当分辨率，同时最小化混叠。 一旦计算，信号尽可能紧凑地表示，以最小化存储和运行时计算要求。

公开(公告)号：US20050080602A1

公开(公告)日：2005-04-14

申请号：US10815140

申请日：2004-03-31

申请人： John Snyder ,  Peter-Pike Sloan ,  Yi-Ren Ng

发明人： John Snyder ,  Peter-Pike Sloan ,  Yi-Ren Ng

IPC分类号： G06F17/10 ,  G06T15/50

CPC分类号： G06T15/506

摘要： The present invention is directed to systems and methods for all-frequency relighting by representing low frequencies of lighting with spherical harmonics and approximate the residual high-frequency energy with point lights. One such embodiment renders low-frequencies with a precomputed radiance transfer (PRT) technique (which requires only a moderate amount of precomputation and storage), while the higher-frequencies are rendered with on-the-fly techniques such as shadow maps and shadow volumes. In addition, various embodiments are directed to a systems and methods for decomposing the lighting into harmonics and sets of point lights. Various alternative embodiments are directed to systems and methods for characterizing the types of environments for which the described decomposition is a viable technique in terms of speed (efficiency) versus quality (realism).

摘要翻译： 本发明涉及通过用球面谐波表示低频照明并用点光近似残余高频能量来进行全频重启的系统和方法。 一个这样的实施例使用预计算辐射传输（PRT）技术（其仅需要适度的预先计算和存储）来实现低频，而较高频率是使用诸如阴影图和阴影体积的飞行技术来渲染的 。 此外，各种实施例涉及用于将照明分解成谐波和点光源的系统和方法。 各种替代实施例涉及用于表征在速度（效率）与质量（实际）方面所描述的分解是可行技术的环境类型的系统和方法。

公开(公告)号：US20050035965A1

公开(公告)日：2005-02-17

申请号：US10641472

申请日：2003-08-15

申请人： Peter-Pike Sloan ,  John Snyder ,  Jesse Hall

发明人： Peter-Pike Sloan ,  John Snyder ,  Jesse Hall

IPC分类号： G06T15/50 ,  G06T15/60

CPC分类号： G06T15/50

摘要： Real-time processing includes per-point transfer matrices forming a high-dimensional surface signal that is compressed using clustered principal component analysis (CPCA). CPCA partitions multiple samples into fewer clusters, each cluster approximating the signal as an affine subspace. Further, source radiance is input to a processor, which approximates source radiance using spherical harmonic basis to produce a set of source radiance coefficients. A graphics processing unit (GPU) processes the source radiance coefficients through the transfer matrix model for each cluster. The result of such processing is the exit radiance, which parameterizes the radiance leaving the surface of the object at each point, thus producing the shading for each point of the virtual object in real time.

摘要翻译： 实时处理包括形成使用聚类主成分分析（CPCA）压缩的高维表面信号的每点传输矩阵。 CPCA将多个样本分成较少的簇，每个簇将信号近似为仿射子空间。 此外，源辐射被输入到处理器，处理器使用球谐函数近似源辐射以产生一组源辐射系数。 图形处理单元（GPU）通过每个簇的传递矩阵模型处理源辐射系数。 这种处理的结果是出射辐射度，其对在每个点处离开物体表面的辐射进行参数化，从而实时地为虚拟物体的每个点产生阴影。

公开(公告)号：US20070257913A1

公开(公告)日：2007-11-08

申请号：US11825918

申请日：2007-07-09

申请人： Peter-Pike Sloan ,  John Snyder ,  Jan Kautz

发明人： Peter-Pike Sloan ,  John Snyder ,  Jan Kautz

IPC分类号： G06T15/60

CPC分类号： G06T15/506

摘要： 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.

公开(公告)号：US20060214931A1

公开(公告)日：2006-09-28

申请号：US11089265

申请日：2005-03-22

申请人： John Snyder ,  Ben Luna ,  Peter-Pike Sloan

发明人： John Snyder ,  Ben Luna ,  Peter-Pike Sloan

IPC分类号： G06T15/50

CPC分类号： G06T15/50

摘要： 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.

公开(公告)号：US20050088440A1

公开(公告)日：2005-04-28

申请号：US10692361

申请日：2003-10-22

申请人： Peter-Pike Sloan ,  John Snyder

发明人： Peter-Pike Sloan ,  John Snyder

IPC分类号： G06T15/50

CPC分类号： G06T15/55

摘要： 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.

摘要翻译： 与之前已知的PRT预计算相比，计算辐射传输系数（例如用于基于预计算辐射传输（PRT）技术的图像渲染中）的硬件加速过程被重新排序以迭代关于对象的方向的采样。 硬件加速过程使用一组表示位置和法线的纹理，用于对建模对象上的点进行抽样。 在迭代方向上，过程计算阴影缓冲区中对象的深度，然后根据阴影缓冲区的法线和位置纹理以及深度计算辐射贡献的纹理。 累积迭代方向的所得辐射贡献纹理以产生表示采样位置的辐射传递系数的纹理。 这使得该过程能够避免图形处理单元的缩小操作，光线跟踪和慢回读路径限制。