Image synthesis algorithms are commonly compared on the basis of running times and/or perceived quality of the generated images. In the case of Monte Carlo techniques, assessment often entails a qualitative impression of convergence toward a reference standard and severity of visible noise; these amount to subjective assessments of the mean and variance of the estimators, respectively. In this paper we argue that such assessments should be augmented by well-known statistical hypothesis testing methods. In particular, we show how to perform a number of such tests to assess random variables that commonly arise in image synthesis such as those estimating irradiance, radiance, pixel color, etc. We explore five broad categories of tests: 1) determining whether the mean is equal to a reference standard, such as an analytical value, 2) determining that the variance is bounded by a given constant, 3) comparing the means of two different random variables, 4) comparing the variances of two different random variables, and 5) verifying that two random variables stem from the same parent distribution. The level of significance of these tests can be controlled by a parameter. We demonstrate that these tests can be used for objective evaluation of Monte Carlo estimators to support claims of zero or small bias and to provide quantitative assessments of variance reduction techniques. We also show how these tests can be used to detect errors in sampling or in computing the density of an importance function in MC integrations.
{"title":"Statistical Hypothesis Testing for Assessing Monte Carlo Estimators: Applications to Image Synthesis","authors":"K. Subr, J. Arvo","doi":"10.1109/PG.2007.55","DOIUrl":"https://doi.org/10.1109/PG.2007.55","url":null,"abstract":"Image synthesis algorithms are commonly compared on the basis of running times and/or perceived quality of the generated images. In the case of Monte Carlo techniques, assessment often entails a qualitative impression of convergence toward a reference standard and severity of visible noise; these amount to subjective assessments of the mean and variance of the estimators, respectively. In this paper we argue that such assessments should be augmented by well-known statistical hypothesis testing methods. In particular, we show how to perform a number of such tests to assess random variables that commonly arise in image synthesis such as those estimating irradiance, radiance, pixel color, etc. We explore five broad categories of tests: 1) determining whether the mean is equal to a reference standard, such as an analytical value, 2) determining that the variance is bounded by a given constant, 3) comparing the means of two different random variables, 4) comparing the variances of two different random variables, and 5) verifying that two random variables stem from the same parent distribution. The level of significance of these tests can be controlled by a parameter. We demonstrate that these tests can be used for objective evaluation of Monte Carlo estimators to support claims of zero or small bias and to provide quantitative assessments of variance reduction techniques. We also show how these tests can be used to detect errors in sampling or in computing the density of an importance function in MC integrations.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125642015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes a method for simulating and visualizing dyeing based on weave patterns and the physical parameters of the threads and the dye. We apply Fick's second law with a variable diffusion coefficient. We calculate the diffusion coefficient using the porosity, tortuosity, and the dye concentration based on the physical chemistry of dyeing. The tortuosity of the channel was incorporated in order to consider the effect of the weave patterns on diffusion. In this model, the total mass is conserved. We describe the cloth model using a two-layered cellular model that includes the essential factors required for representing the weft and warp. Our model also includes a simple dyeing technique that produces dyeing patterns by interrupting the diffusion of the dye in a cloth using a press. The results obtained using our model demonstrate that it is capable of modeling many of the characteristics of dyeing.
{"title":"Geometric Computing in Shape Space","authors":"H. Pottmann","doi":"10.1109/PG.2007.68","DOIUrl":"https://doi.org/10.1109/PG.2007.68","url":null,"abstract":"This paper describes a method for simulating and visualizing dyeing based on weave patterns and the physical parameters of the threads and the dye. We apply Fick's second law with a variable diffusion coefficient. We calculate the diffusion coefficient using the porosity, tortuosity, and the dye concentration based on the physical chemistry of dyeing. The tortuosity of the channel was incorporated in order to consider the effect of the weave patterns on diffusion. In this model, the total mass is conserved. We describe the cloth model using a two-layered cellular model that includes the essential factors required for representing the weft and warp. Our model also includes a simple dyeing technique that produces dyeing patterns by interrupting the diffusion of the dye in a cloth using a press. The results obtained using our model demonstrate that it is capable of modeling many of the characteristics of dyeing.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127646220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Summary form only given. The last few years have brought a more concrete understanding of the mathematical relationship between strokes in drawings, linear features in images, and lines on 3D shapes. However, fundamental questions remain unanswered about how our perceptual system resolves these lines as giving evidence about shape. These questions need to be addressed to assemble mathematically defined lines into clear and compelling drawings. I'll discuss my ongoing research on suggestive contours and highlight lines from this perspective.
{"title":"Communicating 3D Shape Using Lines","authors":"D. DeCarlo","doi":"10.1109/PG.2007.70","DOIUrl":"https://doi.org/10.1109/PG.2007.70","url":null,"abstract":"Summary form only given. The last few years have brought a more concrete understanding of the mathematical relationship between strokes in drawings, linear features in images, and lines on 3D shapes. However, fundamental questions remain unanswered about how our perceptual system resolves these lines as giving evidence about shape. These questions need to be addressed to assemble mathematically defined lines into clear and compelling drawings. I'll discuss my ongoing research on suggestive contours and highlight lines from this perspective.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130999962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper we propose a new volumetric implicit surface data structure as an alternative representation to perform mesh processing algorithms. We introduce a new triangulation algorithm suitable for our voxel-based volumetric structure which is a vector field distance transform from an explicit mesh. This new representation is an extension of the implicit scalar field distance function of a mesh. We show our new vector field function is more accurate than the classic scalar field function by comparing both representations with an error metric evaluation. We adapt to this new vector representation mesh integration operation in the reconstruction process of 3D objects from scanned data which was previously performed on the implicit scalar field function. Results show that using this new vector field representation, our mesh integration and mesh triangulation algorithm designs outperform the previous processes based on the implicit scalar field function representation.
{"title":"A New Volumetric Implicit Surface Data Structure and Its Triangulation Algorithm Applied to Mesh Integration","authors":"M. Fournier, J. Dischler, D. Bechmann","doi":"10.1109/PG.2007.14","DOIUrl":"https://doi.org/10.1109/PG.2007.14","url":null,"abstract":"In this paper we propose a new volumetric implicit surface data structure as an alternative representation to perform mesh processing algorithms. We introduce a new triangulation algorithm suitable for our voxel-based volumetric structure which is a vector field distance transform from an explicit mesh. This new representation is an extension of the implicit scalar field distance function of a mesh. We show our new vector field function is more accurate than the classic scalar field function by comparing both representations with an error metric evaluation. We adapt to this new vector representation mesh integration operation in the reconstruction process of 3D objects from scanned data which was previously performed on the implicit scalar field function. Results show that using this new vector field representation, our mesh integration and mesh triangulation algorithm designs outperform the previous processes based on the implicit scalar field function representation.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114748689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Summary form only given. We argue that real-time domain of interactive games requires completely new approach to algorithms for most problems in computer graphics. To illustrate this point, we describe our recent work on two very different phenomena, human locomotion and fluid simulations, and show how the requirements of high-fidelity, realtime performance and unconditional stability resulted in some very unusual algorithms to these well studied problems.
{"title":"Rethinking Algorithms for Games: Towards High-Fidelity Effects in Interactive Environments","authors":"Zoran Popovic","doi":"10.1109/PG.2007.67","DOIUrl":"https://doi.org/10.1109/PG.2007.67","url":null,"abstract":"Summary form only given. We argue that real-time domain of interactive games requires completely new approach to algorithms for most problems in computer graphics. To illustrate this point, we describe our recent work on two very different phenomena, human locomotion and fluid simulations, and show how the requirements of high-fidelity, realtime performance and unconditional stability resulted in some very unusual algorithms to these well studied problems.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126182025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We introduce a novel mechanism for creating line drawings from three-dimensional models, which captures the dynamic nature of the drawing process. The approach takes into account the interaction between the moving human hand and the drawing instrument. This is demonstrated as applied to the specific problem of making silhouette drawings from polygonal models. A control system drives a pen by tracking the contour of the polygonal model as projected onto the drawing surface, thus mimicking hand motion. The pen is treated as a physically-based object with momentum, giving the generated lines a smooth hand-drawn quality. Lines are rendered using a ribbon metaphor, where thickness is determined by the twist of the ribbon. The twist angle can be dependent upon various attributes such as perspective depth, the curvature of the line, and the lighting of the model. A number of examples are presented, ranging from tightly controlled drawings to expressive gestural drawings.
{"title":"Line Drawing as a Dynamic Process","authors":"D. House, Mayank Singh","doi":"10.1109/PG.2007.62","DOIUrl":"https://doi.org/10.1109/PG.2007.62","url":null,"abstract":"We introduce a novel mechanism for creating line drawings from three-dimensional models, which captures the dynamic nature of the drawing process. The approach takes into account the interaction between the moving human hand and the drawing instrument. This is demonstrated as applied to the specific problem of making silhouette drawings from polygonal models. A control system drives a pen by tracking the contour of the polygonal model as projected onto the drawing surface, thus mimicking hand motion. The pen is treated as a physically-based object with momentum, giving the generated lines a smooth hand-drawn quality. Lines are rendered using a ribbon metaphor, where thickness is determined by the twist of the ribbon. The twist angle can be dependent upon various attributes such as perspective depth, the curvature of the line, and the lighting of the model. A number of examples are presented, ranging from tightly controlled drawings to expressive gestural drawings.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125124833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper proposes to perform reaction-diffusion on surface tiles. The square tiles fit nicely and cost-effectively in GPU memory, whereas we also apply distortion minimization on tiles so as to precisely reduce the unbalanced scale and resolution problem of chemicals in the reaction- diffusion. The interconnection nature of tiles accounts for the surface topology, and thus allows the chemicals to flow naturally over surfaces of arbitrary genus. Furthermore, by taking advantage of the tile structure, we can efficiently perform localized reaction-diffusion, and adjust the pattern formulation in an interactive manner on the GPU. To demonstrate its performance, we develop an interactive system that allows texture designers to fine-tune and alter the reaction-diffusion process by directly painting chemicals onto the object surface. Finally, we also develop several non-trivial applications of reaction-diffusion, including the geometry-dependent reaction-diffusion and deformation-aware reaction-diffusion.
{"title":"Interactive Reaction-Diffusion on Surface Tiles","authors":"Kui-Yip Lo, Hongwei Li, Chi-Wing Fu, T. Wong","doi":"10.1109/PG.2007.19","DOIUrl":"https://doi.org/10.1109/PG.2007.19","url":null,"abstract":"This paper proposes to perform reaction-diffusion on surface tiles. The square tiles fit nicely and cost-effectively in GPU memory, whereas we also apply distortion minimization on tiles so as to precisely reduce the unbalanced scale and resolution problem of chemicals in the reaction- diffusion. The interconnection nature of tiles accounts for the surface topology, and thus allows the chemicals to flow naturally over surfaces of arbitrary genus. Furthermore, by taking advantage of the tile structure, we can efficiently perform localized reaction-diffusion, and adjust the pattern formulation in an interactive manner on the GPU. To demonstrate its performance, we develop an interactive system that allows texture designers to fine-tune and alter the reaction-diffusion process by directly painting chemicals onto the object surface. Finally, we also develop several non-trivial applications of reaction-diffusion, including the geometry-dependent reaction-diffusion and deformation-aware reaction-diffusion.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124203846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Julie Dorsey, Songhua Xu, Gabe Smedresman, H. Rushmeier, L. McMillan
We describe a computer graphics system that supports conceptual architectural design and analysis. We use as a starting point the traditional sketchbook drawings that architects use to experiment with various views, sections, and details. Rather than interpret or infer 3D structure from drawings, our system is designed to allow the designer to organize concept drawings in 3D, and gradually fuse a series of possibly geometrically-inconsistent sketches into a set of 3D strokes. Our system uses strokes and planar "canvases" as basic primitives; the basic mode of input is traditional 2D drawing. We introduce methods for the user to control stroke visibility and transfer strokes between canvases. We also introduce methods for the user to position and orient the canvases that have infinite extent. We demonstrate the use of the system to analyze existing structures and conceive new designs.
{"title":"The Mental Canvas: A Tool for Conceptual Architectural Design and Analysis","authors":"Julie Dorsey, Songhua Xu, Gabe Smedresman, H. Rushmeier, L. McMillan","doi":"10.1109/PG.2007.64","DOIUrl":"https://doi.org/10.1109/PG.2007.64","url":null,"abstract":"We describe a computer graphics system that supports conceptual architectural design and analysis. We use as a starting point the traditional sketchbook drawings that architects use to experiment with various views, sections, and details. Rather than interpret or infer 3D structure from drawings, our system is designed to allow the designer to organize concept drawings in 3D, and gradually fuse a series of possibly geometrically-inconsistent sketches into a set of 3D strokes. Our system uses strokes and planar \"canvases\" as basic primitives; the basic mode of input is traditional 2D drawing. We introduce methods for the user to control stroke visibility and transfer strokes between canvases. We also introduce methods for the user to position and orient the canvases that have infinite extent. We demonstrate the use of the system to analyze existing structures and conceive new designs.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"20 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131574182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rendering global illumination effects for dynamic scenes at interactive frame rates is a computationally challenging task. Much of the computation time needed is spent during visibility queries between individual scene elements, and it is almost illusive to update this information at realtime even for moderately complex scenes. In this paper, we propose a global illumination approach for dynamic scenes that runs at near-real-time frame rates on a single PC. Our method is inspired by the principles of hierarchical radiosity and tackles the visibility problem by implicitly evaluating mutual visibility while constructing a hierarchical link structure between scene elements. By means of the same efficient and easy-to-implement framework, we are able to reproduce a large variety of complex lighting effects for moderately sized scenes, such as interreflections, environment map lighting as well as area light sources.
{"title":"Interactive Global Illumination Using Implicit Visibility","authors":"Z. Dong, J. Kautz, C. Theobalt, H. Seidel","doi":"10.1109/PG.2007.37","DOIUrl":"https://doi.org/10.1109/PG.2007.37","url":null,"abstract":"Rendering global illumination effects for dynamic scenes at interactive frame rates is a computationally challenging task. Much of the computation time needed is spent during visibility queries between individual scene elements, and it is almost illusive to update this information at realtime even for moderately complex scenes. In this paper, we propose a global illumination approach for dynamic scenes that runs at near-real-time frame rates on a single PC. Our method is inspired by the principles of hierarchical radiosity and tackles the visibility problem by implicitly evaluating mutual visibility while constructing a hierarchical link structure between scene elements. By means of the same efficient and easy-to-implement framework, we are able to reproduce a large variety of complex lighting effects for moderately sized scenes, such as interreflections, environment map lighting as well as area light sources.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126458614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we introduce an interactive tool for local color transfer. The new technique is based on the observation that color transfer operations are local in nature while at the same time should adhere global consistency. We introduce a brush by which the user specifies the source and destination image regions for color transfer. Color statistics in the source region are transferred to the destination region. A global optimization is then applied to eliminate vi- sual discontinuities that may result by the local operations. We demonstrate that our tool is easy to use yet effective in quickly generating diverse artistic effects.
{"title":"Color Transfer Brush","authors":"Qing Luan, Fang Wen, Ying-Qing Xu","doi":"10.1109/PG.2007.50","DOIUrl":"https://doi.org/10.1109/PG.2007.50","url":null,"abstract":"In this paper, we introduce an interactive tool for local color transfer. The new technique is based on the observation that color transfer operations are local in nature while at the same time should adhere global consistency. We introduce a brush by which the user specifies the source and destination image regions for color transfer. Color statistics in the source region are transferred to the destination region. A global optimization is then applied to eliminate vi- sual discontinuities that may result by the local operations. We demonstrate that our tool is easy to use yet effective in quickly generating diverse artistic effects.","PeriodicalId":376934,"journal":{"name":"15th Pacific Conference on Computer Graphics and Applications (PG'07)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132428515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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