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Synthesizing Realistic Facial Expressions from Photographs
"... We present new techniques for creating photorealistic textured 3D facial models from photographs of a human subject, and for creating smooth transitions between different facial expressions by morphing between these different models. Starting from several uncalibrated views of a human subject, we em ..."
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Cited by 237 (11 self)
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We present new techniques for creating photorealistic textured 3D facial models from photographs of a human subject, and for creating smooth transitions between different facial expressions by morphing between these different models. Starting from several uncalibrated views of a human subject, we employ a userassisted technique to recover the camera poses corresponding to the views as well as the 3D coordinates of a sparse set of chosen locations on the subject's face. A scattered data interpolation technique is then used to deform a generic face mesh to fit the particular geometry of the subject's face. Having recovered the camera poses and the facial geometry, we extract from the input images one or more texture maps for the model. This process is repeated for several facial expressions of a particular subject. To generate transitions between these facial expressions we use 3D shape morphing between the corresponding face models, while at the same time blending the corresponding tex...
Spherical Wavelets: Efficiently Representing Functions on the Sphere
, 1995
"... Wavelets have proven to be powerful bases for use in numerical analysis and signal processing. Their power lies in the fact that they only require a small number of coefficients to represent general functions and large data sets accurately. This allows compression and efficient computations. Classic ..."
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Cited by 230 (14 self)
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Wavelets have proven to be powerful bases for use in numerical analysis and signal processing. Their power lies in the fact that they only require a small number of coefficients to represent general functions and large data sets accurately. This allows compression and efficient computations. Classical constructions have been limited to simple domains such as intervals and rectangles. In this paper we present a wavelet construction for scalar functions defined on the sphere. We show how biorthogonal wavelets with custom properties can be constructed with the lifting scheme. The bases are extremely easy to implement and allow fully adaptive subdivisions. We give examples of functions defined on the sphere, such as topographic data, bidirectional reflection distribution functions, and illumination, and show how they can be efficiently represented with spherical wavelets.
Scattered Data Interpolation with Multilevel Splines
 IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS
, 1997
"... This paper describes a fast algorithm for scattered data interpolation and approximation. Multilevel Bsplines are introduced to compute a C²continuous surface through a set of irregularly spaced points. The algorithm makes use of a coarsetofine hierarchy of control lattices to generate a sequen ..."
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Cited by 106 (9 self)
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This paper describes a fast algorithm for scattered data interpolation and approximation. Multilevel Bsplines are introduced to compute a C²continuous surface through a set of irregularly spaced points. The algorithm makes use of a coarsetofine hierarchy of control lattices to generate a sequence of bicubic Bspline functions whose sum approaches the desired interpolation function. Large performance gains are realized by using Bspline refinement to reduce the sum of these functions into one equivalent Bspline function. Experimental results demonstrate that highfidelity reconstruction is possible from a selected set of sparse and irregular samples.
Construction of panoramic image mosaics with global and local alignment
 International Journal of Computer Vision,36(2):101
, 2000
"... Abstract. This paper presents a complete system for constructing panoramic image mosaics from sequences of images. Our mosaic representationassociates a transformationmatrix with each input image, rather thanexplicitly projecting all of the images onto a common surface (e.g., a cylinder). In particu ..."
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Cited by 73 (0 self)
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Abstract. This paper presents a complete system for constructing panoramic image mosaics from sequences of images. Our mosaic representationassociates a transformationmatrix with each input image, rather thanexplicitly projecting all of the images onto a common surface (e.g., a cylinder). In particular, to construct a full view panorama, we introduce a rotational mosaic representation that associates a rotation matrix (and optionally a focal length) with each input image. A patchbased alignment algorithm is developed to quickly aligntwo images givenmotionmodels. Techniques for estimating and refining camera focal lengths are also presented. Inorder to reduce accumulated registrationerrors, we apply global alignment (block adjustment) to the whole sequence of images, which results inanoptimally registered image mosaic. To compensate for small amounts of motion parallax introduced by translations of the camera and other unmodeled distortions, we use a local alignment (deghosting) technique which warps each image based on the results of pairwise local image registrations. By combining both global and local alignment, we significantly improve the quality of our image mosaics, thereby enabling the creation of full view panoramic mosaics with handheld cameras. We also present an inverse texture mapping algorithm for efficiently extracting environment maps from our panoramic image mosaics. By mapping the mosaic onto an arbitrary texturemapped polyhedron surrounding the origin, we can explore the virtual environment using standard 3D graphics viewers and hardware without requiring specialpurpose players.
Image alignment and stitching: A tutorial
 MSRTR200492, Microsoft Research, 2004
, 2005
"... This tutorial reviews image alignment and image stitching algorithms. Image alignment algorithms can discover the correspondence relationships among images with varying degrees of overlap. They are ideally suited for applications such as video stabilization, summarization, and the creation of panora ..."
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Cited by 66 (1 self)
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This tutorial reviews image alignment and image stitching algorithms. Image alignment algorithms can discover the correspondence relationships among images with varying degrees of overlap. They are ideally suited for applications such as video stabilization, summarization, and the creation of panoramic mosaics. Image stitching algorithms take the alignment estimates produced by such registration algorithms and blend the images in a seamless manner, taking care to deal with potential problems such as blurring or ghosting caused by parallax and scene movement as well as varying image exposures. This tutorial reviews the basic motion models underlying alignment and stitching algorithms, describes effective direct (pixelbased) and featurebased alignment algorithms, and describes blending algorithms used to produce seamless mosaics. It ends with a discussion of open research problems in the area. 1
Surface Interpolation With Radial Basis Functions for Medical Imaging
 IEEE Transactions on Medical Imaging
, 1997
"... Radial basis functions are presented as a practical solution to the problem of interpolating incomplete surfaces derived from threedimensional (3D) medical graphics. The specific application considered is the design of cranial implants for the repair of defects, usually holes, in the skull. Radial ..."
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Cited by 64 (2 self)
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Radial basis functions are presented as a practical solution to the problem of interpolating incomplete surfaces derived from threedimensional (3D) medical graphics. The specific application considered is the design of cranial implants for the repair of defects, usually holes, in the skull. Radial basis functions impose few restrictions on the geometry of the interpolation centers and are suited to problems where the interpolation centers do not form a regular grid. However, their high computational requirements have previously limited their use to problems where the number of interpolation centers is small (! 300). Recently developed fast evaluation techniques have overcome these limitations and made radial basis interpolation a practical approach for larger data sets. In this paper radial basis functions are fitted to depthmaps of the skull's surface, obtained from Xray CT data using raytracing techniques. They are used to smoothly interpolate the surface of the skull across defe...
Errorbounded reduction of triangle meshes with multivariate data
 In Proceedings of SPIE Symposium on Visual Data Exploration and Analysis III
, 1996
"... Interactive visualization is complicated by the complexity of the objects being visualized. Sampled or computed scientific data is often dense, in order to capture high frequency components in measured data or to accurately model a physical process. Common visualization techniques such as isosurfaci ..."
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Cited by 54 (9 self)
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Interactive visualization is complicated by the complexity of the objects being visualized. Sampled or computed scientific data is often dense, in order to capture high frequency components in measured data or to accurately model a physical process. Common visualization techniques such as isosurfacing on such large meshes generate more geometric primitives than can be rendered in an interactive environment. Geometric mesh reduction techniques have been developed in order to reduce the size of a mesh with little compromise in image quality. Similar techniques have been used for functional surfaces (terrain maps) which take advantage of the planar projection. We extend these methods to arbitrary surfaces in 3D and to any number of variables defined over the mesh by developing a algorithm for mapping from a surface mesh to a reduced representation and measuring the introduced error in both the geometry and the multivariate data. Furthermore, through error propagation, our algorithm ensures that the errors in both the geometric representation and multivariate data do not exceed a userspecified upper bound.
Fitting Scattered Data on SphereLike Surfaces Using Spherical Splines
 J. Comput. Appl. Math
"... . Spaces of polynomial splines defined on planar triangulations are very useful tools for fitting scattered data in the plane. Recently, [4, 5], using homogeneous polynomials, we have developed analogous spline spaces defined on triangulations on the sphere and on spherelike surfaces. Using these s ..."
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Cited by 48 (11 self)
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. Spaces of polynomial splines defined on planar triangulations are very useful tools for fitting scattered data in the plane. Recently, [4, 5], using homogeneous polynomials, we have developed analogous spline spaces defined on triangulations on the sphere and on spherelike surfaces. Using these spaces, it is possible to construct analogs of many of the classical interpolation and fitting methods. Here we examine some of the more interesting ones in detail. For interpolation, we discuss macroelement methods and minimal energy splines, and for fitting, we consider discrete least squares and penalized least squares. 1. Introduction Let S be the unit sphere or a spherelike surface (see Sect. 2 below) in IR 3 . In addition, suppose that we are given a set of scattered points located on S, along with real numbers associated with each of these points. The problem of interest in this paper is to find a function defined on S which either interpolates or approximates these data. This pr...
The Lazy Sweep Ray Casting Algorithm for Rendering Irregular Grids
 IEEE Transactions on Visualization and Computer Graphics
, 1997
"... Lazy Sweep Ray Casting is a fast algorithm for rendering general irregular grids. It is based on the sweepplane paradigm, and it is able to accelerate ray casting for rendering irregular grids, including disconnected and nonconvex (even with holes) unstructured irregular grids with a rendering cost ..."
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Cited by 38 (8 self)
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Lazy Sweep Ray Casting is a fast algorithm for rendering general irregular grids. It is based on the sweepplane paradigm, and it is able to accelerate ray casting for rendering irregular grids, including disconnected and nonconvex (even with holes) unstructured irregular grids with a rendering cost that decreases as the "disconnectedness" decreases. The algorithm is carefully tailored to exploit spatial coherence even if the image resolution differs substantially from the object space resolution. Lazy Sweep Ray Casting has several desirable properties, including its generality, (depthsorting) accuracy, low memory consumption, speed, simplicity of implementation and portability (e.g., no hardware dependencies). We establish the practicality of our method through experimental results based on our implementation, which is shown to be substantially faster (by up to two orders of magnitude) than other algorithms implemented in software. We also provide theoretical results, both lower and ...
PerformanceDriven HandDrawn Animation
, 2000
"... We present a novel method for generating performancedriven, "handdrawn" animation in realtime. Given an annotated set of handdrawn faces for various expressions, our algorithm performs multiway morphs to generate realtime animation that mimics the expressions of a user. Our system consists of ..."
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Cited by 36 (3 self)
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We present a novel method for generating performancedriven, "handdrawn" animation in realtime. Given an annotated set of handdrawn faces for various expressions, our algorithm performs multiway morphs to generate realtime animation that mimics the expressions of a user. Our system consists of a visionbased tracking component and a rendering component. Together, they form an animation system that can be used in a variety of applications, including teleconferencing, multiuser virtual worlds, compressed instructional videos, and consumeroriented animation kits. This paper describes our algorithms in detail and illustrates the potential for this work in a teleconferencing application. Experience with our implementation suggests that there are several advantages to our handdrawn characters over other alternatives: (1) flexibility of animation style; (2) increased compression of expression information; and (3) masking of errors made by the face tracking system that are distracting...