In computer graphics, geometric modeling of complex objects is a difficult process. An important class of complex objects arise from natural phenomena: trees, plants, clouds, mountains, etc. Researchers are at present investigating a variety of techniques for extending modeling capabilities to include these as well as other classes. One mathematical concept that appears to have significant potential for this is fractals. Much interest currently exists in the general scientific community in using fractals as a model of complex natural phenomena. However, only a few methods for generating fractal sets are known. We have been involved in the development of a new approach to computing fractals. Any set of linear maps (affine transformations) and an associated set of probabilities determines an Iterated Function System (IFS). Each IFS has a unique "attractor" which is typically a fractal set (object). Specification of only a few maps can produce very complicated objects. Design of fractal objects is made relatively simple and intuitive by the discovery of an important mathematical property relating the fractal sets to the IFS. The method also provides the possibility of solving the inverse problem. given the geometry of an object, determine an IFS that will (approximately) generate that geometry. This paper presents the application of the theory of IFS to geometric modeling.
{"title":"Construction of fractal objects with iterated function systems","authors":"S. Demko, Laurie Hodges, B. Naylor","doi":"10.1145/325334.325245","DOIUrl":"https://doi.org/10.1145/325334.325245","url":null,"abstract":"In computer graphics, geometric modeling of complex objects is a difficult process. An important class of complex objects arise from natural phenomena: trees, plants, clouds, mountains, etc. Researchers are at present investigating a variety of techniques for extending modeling capabilities to include these as well as other classes. One mathematical concept that appears to have significant potential for this is fractals. Much interest currently exists in the general scientific community in using fractals as a model of complex natural phenomena. However, only a few methods for generating fractal sets are known. We have been involved in the development of a new approach to computing fractals. Any set of linear maps (affine transformations) and an associated set of probabilities determines an Iterated Function System (IFS). Each IFS has a unique \"attractor\" which is typically a fractal set (object). Specification of only a few maps can produce very complicated objects. Design of fractal objects is made relatively simple and intuitive by the discovery of an important mathematical property relating the fractal sets to the IFS. The method also provides the possibility of solving the inverse problem. given the geometry of an object, determine an IFS that will (approximately) generate that geometry. This paper presents the application of the theory of IFS to geometric modeling.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116702340","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}
M. Nadin, C. Csuri, F. Dietrich, Thomas E. Linehan, H. Kawano
As graphics technology and software become more mature, it is critical to examine the aesthetics of computer generated images. Effective visual communication and artistic expression are dependent on aesthetic quality. Issues that emerge for artists, designers and computer scientists include: the formal attributes of images, aesthetic evaluation criteria and the desire to detect or implement aesthetic qualities. The panelists, having studied these and other issues, will present and debate their diverse viewpoints.
{"title":"Aesthetics of computer graphics (panel session)","authors":"M. Nadin, C. Csuri, F. Dietrich, Thomas E. Linehan, H. Kawano","doi":"10.1145/325334.325257","DOIUrl":"https://doi.org/10.1145/325334.325257","url":null,"abstract":"As graphics technology and software become more mature, it is critical to examine the aesthetics of computer generated images. Effective visual communication and artistic expression are dependent on aesthetic quality. Issues that emerge for artists, designers and computer scientists include: the formal attributes of images, aesthetic evaluation criteria and the desire to detect or implement aesthetic qualities. The panelists, having studied these and other issues, will present and debate their diverse viewpoints.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117105703","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 the design and implementation of the University of Alberta user interface management system (UIMS) is discussed. This UIMS is based on the Seeheim model of user interfaces, which divides the user interface into three separate components. The Seeheim model of user interfaces is discussed along with its relationship to the design of UIMSs. The techniques used to design the three user interface components are briefly presented. A mixture of interactive and written notations are used in the design of the user interface. Some interesting features of this UIMS are interactive screen and menu layout, support for three dialogue notations, flexible interface to the application program, ability to adapt to different users, and the use of concurrent processes in user interface implementation The techniques used in the implementation of this UIMS are discussed.
{"title":"The University of Alberta user interface management system","authors":"Mark W. Green","doi":"10.1145/325334.325286","DOIUrl":"https://doi.org/10.1145/325334.325286","url":null,"abstract":"In this paper the design and implementation of the University of Alberta user interface management system (UIMS) is discussed. This UIMS is based on the Seeheim model of user interfaces, which divides the user interface into three separate components. The Seeheim model of user interfaces is discussed along with its relationship to the design of UIMSs. The techniques used to design the three user interface components are briefly presented. A mixture of interactive and written notations are used in the design of the user interface. Some interesting features of this UIMS are interactive screen and menu layout, support for three dialogue notations, flexible interface to the application program, ability to adapt to different users, and the use of concurrent processes in user interface implementation The techniques used in the implementation of this UIMS are discussed.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126099536","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}
Detail enhances the visual richness and realism of computer-generated images. Our stochastic modelling approach, called particle systems, builds complex pictures from sets of simple, volume-filling primitives. For example, structured particle systems have been used to generate trees and a grass-covered forest floor. Particle systems can produce so much irregular, three-dimensional detail that exact shading and visible surface calculations become infeasible. We describe approximate and probabilistic algorithms for shading and the visible surface problem. Because particle systems algorithms generate richly-detailed images, it is hard to detect any deviation from an exact rendering. Recent work in stochastic modelling also enables us to model complex motions with random variation, such as a field of grass blowing in the breeze. We analyze the performance of our current algorithms to understand the costs of our stochastic modelling approach.
{"title":"Approximate and probabilistic algorithms for shading and rendering structured particle systems","authors":"W. Reeves, R. Blau","doi":"10.1145/325334.325250","DOIUrl":"https://doi.org/10.1145/325334.325250","url":null,"abstract":"Detail enhances the visual richness and realism of computer-generated images. Our stochastic modelling approach, called particle systems, builds complex pictures from sets of simple, volume-filling primitives. For example, structured particle systems have been used to generate trees and a grass-covered forest floor. Particle systems can produce so much irregular, three-dimensional detail that exact shading and visible surface calculations become infeasible. We describe approximate and probabilistic algorithms for shading and the visible surface problem. Because particle systems algorithms generate richly-detailed images, it is hard to detect any deviation from an exact rendering. Recent work in stochastic modelling also enables us to model complex motions with random variation, such as a field of grass blowing in the breeze. We analyze the performance of our current algorithms to understand the costs of our stochastic modelling approach.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127118598","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}
The complexity of anti-aliased 3-D rendering systems can be controlled by using a tool-building approach like that of the UNIX™ text-processing tools. Such an approach requires a simple picture representation amenable to anti-aliasing that all rendering programs can produce, a compositing algorithm for that representation and a command language to piece together scenes. This paper advocates a representation that combines Porter and Duff's compositing algebra with a Z-buffer to provide simple anti-aliased 3-D compositing.
{"title":"Compositing 3-D rendered images","authors":"Tom Duff","doi":"10.1145/325334.325174","DOIUrl":"https://doi.org/10.1145/325334.325174","url":null,"abstract":"The complexity of anti-aliased 3-D rendering systems can be controlled by using a tool-building approach like that of the UNIX™ text-processing tools. Such an approach requires a simple picture representation amenable to anti-aliasing that all rendering programs can produce, a compositing algorithm for that representation and a command language to piece together scenes. This paper advocates a representation that combines Porter and Duff's compositing algebra with a Z-buffer to provide simple anti-aliased 3-D compositing.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122318590","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}
Artists using conventional computer graphic input devices cannot produce the same visual effects which they can with traditional tools and media. The drawing prism is a new device which allows people to draw or paint directly into a frame buffer, using brushes, their hands, or a variety of other objects. These objects can be manipulated to achieve continuously adjustable line qualities and textures, in the same ways that artists have traditionally used their hands and tools.The device uses one face of a large transparent prisms as a drawing surface. A video camera views that surface from an angle such that it can only image the points of optical contact between drawing tools and the surface. These images are digitized and processed in real time so as to build up a drawing as the tools are moved along the surface. A layer of transparent liquid helps tools make optical contact with the drawing surface. Any light colored object can thus be used as a drawing tool.Details of the current implementation are provided along with suggestions for improving its resolution. Combinations of visual effects previously restricted to either traditional media or computer graphics are described and illustrated.
{"title":"The drawing prism: a versatile graphic input device","authors":"R. Greene","doi":"10.1145/325334.325202","DOIUrl":"https://doi.org/10.1145/325334.325202","url":null,"abstract":"Artists using conventional computer graphic input devices cannot produce the same visual effects which they can with traditional tools and media. The drawing prism is a new device which allows people to draw or paint directly into a frame buffer, using brushes, their hands, or a variety of other objects. These objects can be manipulated to achieve continuously adjustable line qualities and textures, in the same ways that artists have traditionally used their hands and tools.The device uses one face of a large transparent prisms as a drawing surface. A video camera views that surface from an angle such that it can only image the points of optical contact between drawing tools and the surface. These images are digitized and processed in real time so as to build up a drawing as the tools are moved along the surface. A layer of transparent liquid helps tools make optical contact with the drawing surface. Any light colored object can thus be used as a drawing tool.Details of the current implementation are provided along with suggestions for improving its resolution. Combinations of visual effects previously restricted to either traditional media or computer graphics are described and illustrated.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127052438","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}
Stochastic sampling techniques, in particular Poisson and fittered sampling, are developed and analyzed. These approaches allow the construction of alias-free approximations to continuous functions using discrete calculations. Stochastic sampling scatters high frequency information into broadband noise rather than generating the false patterne produced by regular sampling. The type of randomness used in the sampling process controls the spectral character of the noise. The average sampling rate and the function being sampled determine the amount of noise that is produced. Stochastic sampling is applied adaptively so that a greater number of samples are taken where the function varies most. An estimate is used to determine how many samples to take over a given region. Noise reducing filters are used to increase the efficacy of a given sampling rate. The filter width is adaptively controlled to further improve performance. Stochastic sampling can be applied spatiotemporally as well as to other aspects of scene simulation. Ray tracing is one example of an image synthesis approach that can be antialiased by stochastic sampling.
{"title":"Antialiasing through stochastic sampling","authors":"Mark A. Z. Dippé, E. Wold","doi":"10.1145/325334.325182","DOIUrl":"https://doi.org/10.1145/325334.325182","url":null,"abstract":"Stochastic sampling techniques, in particular Poisson and fittered sampling, are developed and analyzed. These approaches allow the construction of alias-free approximations to continuous functions using discrete calculations. Stochastic sampling scatters high frequency information into broadband noise rather than generating the false patterne produced by regular sampling. The type of randomness used in the sampling process controls the spectral character of the noise. The average sampling rate and the function being sampled determine the amount of noise that is produced. Stochastic sampling is applied adaptively so that a greater number of samples are taken where the function varies most. An estimate is used to determine how many samples to take over a given region. Noise reducing filters are used to increase the efficacy of a given sampling rate. The filter width is adaptively controlled to further improve performance. Stochastic sampling can be applied spatiotemporally as well as to other aspects of scene simulation. Ray tracing is one example of an image synthesis approach that can be antialiased by stochastic sampling.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134403436","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}
Parametric keyframing is a popular animation technique where values for parameters which control the position, orientation, size, and shape of modeled objects are determined at key times, then interpolated for smooth animation. Typically the parameter values defined by the keyframes are interpolated by spline techniques with the result that the parameter change kinetics are implicitly defined by the given keyframe times and data points. Existing interpolation systems for animation are examined and found to lack certain desirable features such as continuity of acceleration or convenient kinetic control. The requirements of interpolation for animation are analyzed in order to determine the characteristics of a satisfactory system. A new interpolation system is developed and implemented which incorporates second-derivative continuity (continuity of acceleration), local control, convenient kinetic control, and joining and phrasing of successive motions. Phrasing control includes the ability to parametrically control the degree and extent of smooth motion flow between separately defined motions.
{"title":"Parametric keyframe interpolation incorporating kinetic adjustment and phrasing control","authors":"Scott N. Steketee, N. Badler","doi":"10.1145/325334.325243","DOIUrl":"https://doi.org/10.1145/325334.325243","url":null,"abstract":"Parametric keyframing is a popular animation technique where values for parameters which control the position, orientation, size, and shape of modeled objects are determined at key times, then interpolated for smooth animation. Typically the parameter values defined by the keyframes are interpolated by spline techniques with the result that the parameter change kinetics are implicitly defined by the given keyframe times and data points. Existing interpolation systems for animation are examined and found to lack certain desirable features such as continuity of acceleration or convenient kinetic control. The requirements of interpolation for animation are analyzed in order to determine the characteristics of a satisfactory system. A new interpolation system is developed and implemented which incorporates second-derivative continuity (continuity of acceleration), local control, convenient kinetic control, and joining and phrasing of successive motions. Phrasing control includes the ability to parametrically control the degree and extent of smooth motion flow between separately defined motions.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131424406","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}
C. Bigelow, P. Coueignoux, J. Hobby, Peter Karow, V. Pratt, Luis Trabb Pardo, J. E. Warnock
Issues involved in computer generated video animation will be addressed by the producers of the video and the clients who use the product. The producers of computer generated video include independent production houses and production departments within the television networks. The clients include advertising agencies and the news, sports and entertainment departments of the television networks themselves. Topics to be discussed include design control, equipment used and cost. Issues such as in-house production vs. contracted production and daily production schedules vs. longer term promotional projects will also be discussed.
{"title":"Font formats (panel session)","authors":"C. Bigelow, P. Coueignoux, J. Hobby, Peter Karow, V. Pratt, Luis Trabb Pardo, J. E. Warnock","doi":"10.1145/325334.325256","DOIUrl":"https://doi.org/10.1145/325334.325256","url":null,"abstract":"Issues involved in computer generated video animation will be addressed by the producers of the video and the clients who use the product. The producers of computer generated video include independent production houses and production departments within the television networks. The clients include advertising agencies and the news, sports and entertainment departments of the television networks themselves. Topics to be discussed include design control, equipment used and cost. Issues such as in-house production vs. contracted production and daily production schedules vs. longer term promotional projects will also be discussed.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127232294","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}
A method is presented for representing botanical trees, given three-dimensional points and connections. Limbs are modeled as generalized cylinders whose axes are space curves that interpolate the points. A free-form surface connects branching limbs. "Blobby" techniques are used to model the tree trunk as a series of non-circular cross sections. Bark is simulated with a bump map digitized from real world bark; leaves are textures mapped onto simple surfaces.
{"title":"Modeling the mighty maple","authors":"J. Bloomenthal","doi":"10.1145/325334.325249","DOIUrl":"https://doi.org/10.1145/325334.325249","url":null,"abstract":"A method is presented for representing botanical trees, given three-dimensional points and connections. Limbs are modeled as generalized cylinders whose axes are space curves that interpolate the points. A free-form surface connects branching limbs. \"Blobby\" techniques are used to model the tree trunk as a series of non-circular cross sections. Bark is simulated with a bump map digitized from real world bark; leaves are textures mapped onto simple surfaces.","PeriodicalId":163416,"journal":{"name":"Proceedings of the 12th annual conference on Computer graphics and interactive techniques","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116853808","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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