A novel stochastic modeling technique is described which operates on a voxel data base in which objects are represented as collections of voxel records. Models are "grown" from predefined geometric elements according to rules based on simple relationships like intersection, proximity, and occlusion which can be evaluated more quickly and easily in voxel space than with analytic geometry. Growth is probabilistic: multiple trials are attempted in which an element's position and orientation are randomly perturbed, and the trial which best fits a set of rules is selected. The term voxel space automata is introduced to describe growth processes that sense and react to a voxel environment.Applications include simulation of plant growth, for which voxel representation facilitates sensing the environment. Illumination can be efficiently estimated at each plant "node" at each growth iteration by casting rays into the voxel environment, allowing accurate simulation of reaction to light including heliotropism.
{"title":"Voxel space automata: modeling with stochastic growth processes in voxel space","authors":"Ned Greene","doi":"10.1145/74333.74351","DOIUrl":"https://doi.org/10.1145/74333.74351","url":null,"abstract":"A novel stochastic modeling technique is described which operates on a voxel data base in which objects are represented as collections of voxel records. Models are \"grown\" from predefined geometric elements according to rules based on simple relationships like intersection, proximity, and occlusion which can be evaluated more quickly and easily in voxel space than with analytic geometry. Growth is probabilistic: multiple trials are attempted in which an element's position and orientation are randomly perturbed, and the trial which best fits a set of rules is selected. The term voxel space automata is introduced to describe growth processes that sense and react to a voxel environment.Applications include simulation of plant growth, for which voxel representation facilitates sensing the environment. Illumination can be efficiently estimated at each plant \"node\" at each growth iteration by casting rays into the voxel environment, allowing accurate simulation of reaction to light including heliotropism.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"134 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128546724","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 system for constructing graphical user interfaces following a two-view paradigm: one view contains a textual representation of the interface in a special-purpose, "little" language, and the other view contains a direct manipulation, interactive editor for the user interface. The user interface can be edited in either view, and the changes are reflected in the other view. The language allows dialog boxes to be expressed in a simple and natural way, and has a well-defined mapping into the interactive editor. A base set of interactors is currently available, but the system can be easily extended with more interactors. We believe this approach to building user interfaces combines the advantages of the direct manipulation, WYSIWYG approach with the advantages of the textual, descriptive approach, and does not suffer from the limitations of either approach.
{"title":"A two-view approach to constructing user interfaces","authors":"Gideon Avrahami, Kenneth P. Brooks, Marc H. Brown","doi":"10.1145/74333.74347","DOIUrl":"https://doi.org/10.1145/74333.74347","url":null,"abstract":"This paper describes a system for constructing graphical user interfaces following a two-view paradigm: one view contains a textual representation of the interface in a special-purpose, \"little\" language, and the other view contains a direct manipulation, interactive editor for the user interface. The user interface can be edited in either view, and the changes are reflected in the other view. The language allows dialog boxes to be expressed in a simple and natural way, and has a well-defined mapping into the interactive editor. A base set of interactors is currently available, but the system can be easily extended with more interactors. We believe this approach to building user interfaces combines the advantages of the direct manipulation, WYSIWYG approach with the advantages of the textual, descriptive approach, and does not suffer from the limitations of either approach.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"405 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124316411","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 analyse some recent approaches to the global illumination problem by introducing the corresponding reflection operators, and we demonstrate the advantages of a two-pass method. A generalization of the system introduced by Wallace et al. at Siggraph '87 to integrate diffuse as well as specular effects is presented. It is based on the calculation of extended form-factors, which allows arbitrary geometries to be used in the scene description, as well as refraction effects. We also present a new sampling method for the calculation of form-factors, which is an alternative to the hemi-cube technique introduced by Cohen and Greenberg for radiosity calculations. This method is particularly well suited to the extended form-factors calculation. The problem of interactive display of the picture being created is also addressed by using hardware-assisted projections and image composition to recreate a complete specular view of the scene.
{"title":"A general two-pass method integrating specular and diffuse reflection","authors":"F. Sillion, C. Puech","doi":"10.1145/74333.74368","DOIUrl":"https://doi.org/10.1145/74333.74368","url":null,"abstract":"We analyse some recent approaches to the global illumination problem by introducing the corresponding reflection operators, and we demonstrate the advantages of a two-pass method. A generalization of the system introduced by Wallace et al. at Siggraph '87 to integrate diffuse as well as specular effects is presented. It is based on the calculation of extended form-factors, which allows arbitrary geometries to be used in the scene description, as well as refraction effects. We also present a new sampling method for the calculation of form-factors, which is an alternative to the hemi-cube technique introduced by Cohen and Greenberg for radiosity calculations. This method is particularly well suited to the extended form-factors calculation. The problem of interactive display of the picture being created is also addressed by using hardware-assisted projections and image composition to recreate a complete specular view of the scene.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"69 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130147451","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 give an efficient, randomized hidden surface removal algorithm, with the best time complexity so far. A distinguishing feature of this algorithm is that the expected time spent by this algorithm on junctions which are at the "obstruction level" l, with respect to the viewer, is inversely proportional to l. This provably holds for any input, regardless of the way in which faces are located in the scene, because the expectation is with respect to randomization in the algorithm, and does not depend on the input. In practice, this means that the time complexity is roughly proportional to the size of the actually visible output times logarithm of the average depth complexity of the scene (this logarithm is very small generally).
{"title":"An efficient algorithm for hidden surface removal","authors":"K. Mulmuley","doi":"10.1145/74333.74372","DOIUrl":"https://doi.org/10.1145/74333.74372","url":null,"abstract":"We give an efficient, randomized hidden surface removal algorithm, with the best time complexity so far. A distinguishing feature of this algorithm is that the expected time spent by this algorithm on junctions which are at the \"obstruction level\" l, with respect to the viewer, is inversely proportional to l. This provably holds for any input, regardless of the way in which faces are located in the scene, because the expectation is with respect to randomization in the algorithm, and does not depend on the input. In practice, this means that the time complexity is roughly proportional to the size of the actually visible output times logarithm of the average depth complexity of the scene (this logarithm is very small generally).","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124962612","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}
Michael F. Cohen, D. Greenberg, Shenchang Eric Chen, John R. Wallace, John R. Wallace, K. Elmquist
A new method for computing form-factors within a progressive radiosity approach is presented. Previously, the progressive radiosity approach has depended on the use of the hemi-cube algorithm to determine form-factors. However, sampling problems inherent in the hemi-cube algorithm limit its usefulness for complex images. A more robust approach is described in which ray tracing is used to perform the numerical integration of the form-factor equation. The approach is tailored to provide good, approximate results for a low number of rays, while still providing a smooth continuum of increasing accuracy for higher numbers of rays. Quantitative comparisons between analytically derived form-factors and ray traced form-factors are presented.
{"title":"A Ray tracing algorithm for progressive radiosity","authors":"Michael F. Cohen, D. Greenberg, Shenchang Eric Chen, John R. Wallace, John R. Wallace, K. Elmquist","doi":"10.1145/74333.74366","DOIUrl":"https://doi.org/10.1145/74333.74366","url":null,"abstract":"A new method for computing form-factors within a progressive radiosity approach is presented. Previously, the progressive radiosity approach has depended on the use of the hemi-cube algorithm to determine form-factors. However, sampling problems inherent in the hemi-cube algorithm limit its usefulness for complex images. A more robust approach is described in which ray tracing is used to perform the numerical integration of the form-factor equation. The approach is tailored to provide good, approximate results for a low number of rays, while still providing a smooth continuum of increasing accuracy for higher numbers of rays. Quantitative comparisons between analytically derived form-factors and ray traced form-factors are presented.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"134 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133888813","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}
Current radiosity methods rely on the calculation of geometric factors, known as form-factors, which describe energy exchange between pairs of surfaces in the environment. The most computationally efficient method for form-factor generation is a numerical technique known as the hemi-cube algorithm. Use of the hemi-cube is based on assumptions about the geometry of the surfaces involved. First, this paper examines the types of errors and visual artifacts that result when these assumptions are violated. Second, the paper shows that these errors occur more frequently in progressive refinement radiosity than in the originally proposed full matrix radiosity solution. Next, a new analytical technique for determining form-factors that is immune to the errors of the hemi-cube algorithm is introduced. Finally, a hybrid progressive refinement method that invokes the new technique to correctly compute form-factors when hemi-cube assumptions are violated is presented.
{"title":"Improving radiosity solutions through the use of analytically determined form-factors","authors":"D. Baum, H. Rushmeier, J. Winget, G. Woodruff","doi":"10.1145/74333.74367","DOIUrl":"https://doi.org/10.1145/74333.74367","url":null,"abstract":"Current radiosity methods rely on the calculation of geometric factors, known as form-factors, which describe energy exchange between pairs of surfaces in the environment. The most computationally efficient method for form-factor generation is a numerical technique known as the hemi-cube algorithm. Use of the hemi-cube is based on assumptions about the geometry of the surfaces involved. First, this paper examines the types of errors and visual artifacts that result when these assumptions are violated. Second, the paper shows that these errors occur more frequently in progressive refinement radiosity than in the originally proposed full matrix radiosity solution. Next, a new analytical technique for determining form-factors that is immune to the errors of the hemi-cube algorithm is introduced. Finally, a hybrid progressive refinement method that invokes the new technique to correctly compute form-factors when hemi-cube assumptions are violated is presented.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116760606","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 accurate color reproduction among a wide variety of display devices. The method is very general, in that it may be applied to virtually any color display device. Its generality has been demonstrated by application to color monitors, film recorders, electronic pre-press systems and color hardcopy devices. The algorithm has been used to accurately translate between device dependent and device independent color specifications and to translate from one device dependent color specification to another.The method separates the color reproduction process into two distinct components: device characterization, which accounts for the colorimetric properties of each class of display device, and device calibration, which accounts for local variations from one instance of a device to another.A companded RGB color space is introduced, which is used with trivariate parametric polynomial volumes (i.e. hyperpatches) to perform accurate color transformations.A color separation algorithm is presented which converts companded RGB to and from the subtractive printing colors (cyan, magenta, yellow, black) using gray component replacement.
{"title":"Accurate color reproduction for computer graphics applications","authors":"Bruce J. Lindbloom","doi":"10.1145/74333.74345","DOIUrl":"https://doi.org/10.1145/74333.74345","url":null,"abstract":"A method is presented for accurate color reproduction among a wide variety of display devices. The method is very general, in that it may be applied to virtually any color display device. Its generality has been demonstrated by application to color monitors, film recorders, electronic pre-press systems and color hardcopy devices. The algorithm has been used to accurately translate between device dependent and device independent color specifications and to translate from one device dependent color specification to another.The method separates the color reproduction process into two distinct components: device characterization, which accounts for the colorimetric properties of each class of display device, and device calibration, which accounts for local variations from one instance of a device to another.A companded RGB color space is introduced, which is used with trivariate parametric polynomial volumes (i.e. hyperpatches) to perform accurate color transformations.A color separation algorithm is presented which converts companded RGB to and from the subtractive printing colors (cyan, magenta, yellow, black) using gray component replacement.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129697403","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 presents a hybrid approach to the animation of human locomotion which combines goal-directed and dynamic motion control. Knowledge about a locomotion cycle is incorporated into a hierarchical control process. The desired locomotion is conveniently specified at the top level as a task (e.g. walk at speed v), which is then decomposed by application of the concepts of step symmetry and state-phase-timings. As a result of this decomposition, the forces and torques that drive the dynamic model of the legs are determined by numerical approximation techniques. Rather than relying on a general dynamic model, the equations of motion of the legs are tailored to locomotion and analytically constrained to allow for only a specific range of movements. The dynamics of the legs produce a generic, natural locomotion pattern which is visually upgraded by some kinematic "cosmetics" derived from such principles as virtual leg and determinants of gait. A system has been implemented based on these principles and has shown that when a few parameters, such as velocity, step length and step frequency are specified, a wide variety of human walks can be generated in almost real-time.
{"title":"Goal-directed, dynamic animation of human walking","authors":"Armin Bruderlin, T. Calvert","doi":"10.1145/74333.74357","DOIUrl":"https://doi.org/10.1145/74333.74357","url":null,"abstract":"This paper presents a hybrid approach to the animation of human locomotion which combines goal-directed and dynamic motion control. Knowledge about a locomotion cycle is incorporated into a hierarchical control process. The desired locomotion is conveniently specified at the top level as a task (e.g. walk at speed v), which is then decomposed by application of the concepts of step symmetry and state-phase-timings. As a result of this decomposition, the forces and torques that drive the dynamic model of the legs are determined by numerical approximation techniques. Rather than relying on a general dynamic model, the equations of motion of the legs are tailored to locomotion and analytically constrained to allow for only a specific range of movements. The dynamics of the legs produce a generic, natural locomotion pattern which is visually upgraded by some kinematic \"cosmetics\" derived from such principles as virtual leg and determinants of gait. A system has been implemented based on these principles and has shown that when a few parameters, such as velocity, step length and step frequency are specified, a wide variety of human walks can be generated in almost real-time.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129583186","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}
Computer simulations can be used to generate the spatial and temporal data describing the acoustical behavior of performance halls, but typically the analytical results are difficult to assimilate and compare. By using computer graphics to display the multi-dimensional data, substantially greater amounts of information than that conveyed by standard techniques can be communicated to the designer. This allows designs of different acoustical spaces to be tested, evaluated, and compared.An example comparing the acoustical behavior of three different concert halls demonstrates these techniques and allows for the simultaneous assimilation of much of the information necessary to evaluate the acoustical nature of a space. The use of three-dimensional images, color, animation and abstract representation allows for the comprehension of the complex results of a scientific simulation. Specifically, the simultaneous display of particular icons familiar to the discipline enabled the simultaneous presentation of up to twelve parameters.From a more general point of view, the procedures demonstrate how computer graphics can be utilized for the portrayal of multi-dimensional time dependent data. The visualization techniques are potentially useful for the display of three-dimensional vector fields in many scientific and design applications.
{"title":"Computer graphics visualization for acoustic simulation","authors":"A. Stettner, D. Greenberg","doi":"10.1145/74333.74353","DOIUrl":"https://doi.org/10.1145/74333.74353","url":null,"abstract":"Computer simulations can be used to generate the spatial and temporal data describing the acoustical behavior of performance halls, but typically the analytical results are difficult to assimilate and compare. By using computer graphics to display the multi-dimensional data, substantially greater amounts of information than that conveyed by standard techniques can be communicated to the designer. This allows designs of different acoustical spaces to be tested, evaluated, and compared.An example comparing the acoustical behavior of three different concert halls demonstrates these techniques and allows for the simultaneous assimilation of much of the information necessary to evaluate the acoustical nature of a space. The use of three-dimensional images, color, animation and abstract representation allows for the comprehension of the complex results of a scientific simulation. Specifically, the simultaneous display of particular icons familiar to the discipline enabled the simultaneous presentation of up to twelve parameters.From a more general point of view, the procedures demonstrate how computer graphics can be utilized for the portrayal of multi-dimensional time dependent data. The visualization techniques are potentially useful for the display of three-dimensional vector fields in many scientific and design applications.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121198325","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 present a method for rendering scenes with fine detail via an object called a texel, a rendering primitive inspired by volume densities mixed with anisotropic lighting models. This technique solves a long outstanding problem in image synthesis: the rendering of furry surfaces.
{"title":"Rendering fur with three dimensional textures","authors":"J. Kajiya, Timothy L. Kay","doi":"10.1145/74333.74361","DOIUrl":"https://doi.org/10.1145/74333.74361","url":null,"abstract":"We present a method for rendering scenes with fine detail via an object called a texel, a rendering primitive inspired by volume densities mixed with anisotropic lighting models. This technique solves a long outstanding problem in image synthesis: the rendering of furry surfaces.","PeriodicalId":422743,"journal":{"name":"Proceedings of the 16th annual conference on Computer graphics and interactive techniques","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126950738","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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