In image synthesis, cloth objects such as clothes are most often modelled as textures mapped onto rigid surfaces. However, in order to represent such objects more realistically, their physical properties must be examined. This paper describes a method for modelling cloth material hanging in three dimensions when supported by any number of constraint points. The cloth synthesized with this model contains folds and appears more realistic than simple texture mapping. This paper also describes a method for rendering the cloth once its free-hanging shape has been determined.The computation of the surface of a free-hanging cloth is performed in two stages. The first stage approximates the shape of the surface which is interior to the constraint points, and the second stage performs a relaxation process on all points on the surface to arrive at a close approximation to its shape. The rendering of the surfaces is done using a ray-tracer which treats the surface as a mesh of line segments.
{"title":"The synthesis of cloth objects","authors":"Jerry Weil","doi":"10.1145/15922.15891","DOIUrl":"https://doi.org/10.1145/15922.15891","url":null,"abstract":"In image synthesis, cloth objects such as clothes are most often modelled as textures mapped onto rigid surfaces. However, in order to represent such objects more realistically, their physical properties must be examined. This paper describes a method for modelling cloth material hanging in three dimensions when supported by any number of constraint points. The cloth synthesized with this model contains folds and appears more realistic than simple texture mapping. This paper also describes a method for rendering the cloth once its free-hanging shape has been determined.The computation of the surface of a free-hanging cloth is performed in two stages. The first stage approximates the shape of the surface which is interior to the constraint points, and the second stage performs a relaxation process on all points on the surface to arrive at a close approximation to its shape. The rendering of the surfaces is done using a ray-tracer which treats the surface as a mesh of line segments.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81566577","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 general radiosity method accounting for all interreflections of light between diffuse and nondiffuse surfaces in complex environments is introduced. As contrasted with previous radiosity methods, surfaces are no longer required to be perfectly diffuse reflectors and emitters. A complete, viewer independent description of the light leaving each surface in each direction is computed, allowing dynamic sequences of images to be rendered with little additional computation per image. Phenomena such as "reflection tracking", reflections following a moving observer across a specular surface are produced. Secondary light sources, such as the light from a spotlight reflecting off a mirror onto a wall are also accounted for.
{"title":"A radiosity method for non-diffuse environments","authors":"David S. Immel, Michael F. Cohen, D. Greenberg","doi":"10.1145/15922.15901","DOIUrl":"https://doi.org/10.1145/15922.15901","url":null,"abstract":"A general radiosity method accounting for all interreflections of light between diffuse and nondiffuse surfaces in complex environments is introduced. As contrasted with previous radiosity methods, surfaces are no longer required to be perfectly diffuse reflectors and emitters. A complete, viewer independent description of the light leaving each surface in each direction is computed, allowing dynamic sequences of images to be rendered with little additional computation per image. Phenomena such as \"reflection tracking\", reflections following a moving observer across a specular surface are produced. Secondary light sources, such as the light from a spotlight reflecting off a mirror onto a wall are also accounted for.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90989409","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}
An algorithm is presented for automatically converting data representing unambiguous, three-dimensional objects in wire-frame form with curvilinear edges into a boundary representation. The method is an important extension to a previously published algorithm based on graph theory and topology. The new method automatically detects and resolves anomalies, such as necks which may appear to be faces, that formerly required human intervention. The topological basis for the solution to this problem is given along with a description of what topological properties a well defined three-dimensional object should have. An implementation has been coded and examples of results are included.
{"title":"Automated conversion of curvilinear wire-frame models to surface boundary models; a topological approach","authors":"J. A. Brewer, S. Courter","doi":"10.1145/15922.15905","DOIUrl":"https://doi.org/10.1145/15922.15905","url":null,"abstract":"An algorithm is presented for automatically converting data representing unambiguous, three-dimensional objects in wire-frame form with curvilinear edges into a boundary representation. The method is an important extension to a previously published algorithm based on graph theory and topology. The new method automatically detects and resolves anomalies, such as necks which may appear to be faces, that formerly required human intervention. The topological basis for the solution to this problem is given along with a description of what topological properties a well defined three-dimensional object should have. An implementation has been coded and examples of results are included.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90830762","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 shadow volume algorithm of Frank Crow was reorganized to provide information on the regions of illuminated space in front of each visible surface. This information is used to calculate the extra intensity due to atmospheric scattering, so when the atmosphere is partly in shadow, columns of scattered light will be visible. For efficiency in sorting the shadow edges, the image is computed in polar coordinates.
{"title":"Atmospheric illumination and shadows","authors":"N. Max","doi":"10.1145/15922.15899","DOIUrl":"https://doi.org/10.1145/15922.15899","url":null,"abstract":"The shadow volume algorithm of Frank Crow was reorganized to provide information on the regions of illuminated space in front of each visible surface. This information is used to calculate the extra intensity due to atmospheric scattering, so when the atmosphere is partly in shadow, columns of scattered light will be visible. For efficiency in sorting the shadow edges, the image is computed in polar coordinates.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84861055","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}
Image rendering is the performance bottleneck in many computer-graphics systems today because of its computation-intensive nature. Described here is a one-chip VLSI implementation of a shaded-polygon renderer which provides an affordable solution to the bottleneck. The chip takes advantage of a unique extension to Bresenham's vector drawing algorithm [1] to interpolate four axes (for Red, Green, Blue and Z) across a polygon, in addition to the X and Y values. Its inherent accuracy and ease of high-speed hardware implementation distinguish this new algorithm from interpolation with incrementing fractions (DDA).This chip was designed as part of a workstation primarily for mechanical engineering CAD applications. The pipelining and internal bandwidth possible on the chip allows rendering speeds of over twelve-thousand, 1000-pixel, shaded polygons per second, suitable for interactive manipulation of solids. Described in this paper is the derivation of the new algorithm and its implementation in a pipelined, polygon-rendering chip.
{"title":"A fast shaded-polygon renderer","authors":"R. Swanson, L. Thayer","doi":"10.1145/15922.15896","DOIUrl":"https://doi.org/10.1145/15922.15896","url":null,"abstract":"Image rendering is the performance bottleneck in many computer-graphics systems today because of its computation-intensive nature. Described here is a one-chip VLSI implementation of a shaded-polygon renderer which provides an affordable solution to the bottleneck. The chip takes advantage of a unique extension to Bresenham's vector drawing algorithm [1] to interpolate four axes (for Red, Green, Blue and Z) across a polygon, in addition to the X and Y values. Its inherent accuracy and ease of high-speed hardware implementation distinguish this new algorithm from interpolation with incrementing fractions (DDA).This chip was designed as part of a workstation primarily for mechanical engineering CAD applications. The pipelining and internal bandwidth possible on the chip allows rendering speeds of over twelve-thousand, 1000-pixel, shaded polygons per second, suitable for interactive manipulation of solids. Described in this paper is the derivation of the new algorithm and its implementation in a pipelined, polygon-rendering chip.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"322 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80283375","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 image generation systems often represent curved surfaces as a mesh of planar polygons that are shaded to restore a smooth appearance. Phong shading is a well known algorithm for producing a realistic shading but it has not been used by real-time systems because of the 3 additions, 1 division, and 1 square-root required per pixel for its evaluation. We describe a new formulation for Phong shading that reduces the amount of computation per pixel to only 2 additions for simple Lambertian reflection and 5 additions and 1 memory reference for Phong's complete reflection model. We also show how to extend our method to compute the specular component with the eye at a finite distance from the scene rather than at infinity as is usually assumed. The method can be implemented in hardware for real-time applications or in software to speed image generation for almost any system.
{"title":"Fast Phong shading","authors":"G. Bishop, D. Weimer","doi":"10.1145/15922.15897","DOIUrl":"https://doi.org/10.1145/15922.15897","url":null,"abstract":"Computer image generation systems often represent curved surfaces as a mesh of planar polygons that are shaded to restore a smooth appearance. Phong shading is a well known algorithm for producing a realistic shading but it has not been used by real-time systems because of the 3 additions, 1 division, and 1 square-root required per pixel for its evaluation. We describe a new formulation for Phong shading that reduces the amount of computation per pixel to only 2 additions for simple Lambertian reflection and 5 additions and 1 memory reference for Phong's complete reflection model. We also show how to extend our method to compute the specular component with the eye at a finite distance from the scene rather than at infinity as is usually assumed. The method can be implemented in hardware for real-time applications or in software to speed image generation for almost any system.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"183 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80458498","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 program for the real-time display of computer animation on a bit-mapped raster display is presented. The differential compiler performs temporal domain image data compression using frame replenishment coding on successive frames of animation stored in memory as bitmaps and saves only the differences. A small run-time interpreter then retrieves and displays the differences in real-time to create the animated effect. This results in a significant reduction in storage requirements, and allows animation on general purpose computers which would otherwise be too slow or have insufficient memory. Frame creation is both device and method independent. An animation environment supports interactive editing capabilities, reconstructing any arbitrary desired frame for later modification. Frames can be added, modified, or deleted, and the animated sequence can be viewed at any point during the session. The compiler is automatically called as needed; its operation is transparent to the user. The compiler is described in detail, both in terms of data compression and the requirements of interactive animation editing.
{"title":"A differential compiler for computer animation","authors":"M. Denber, Paul M. Turner","doi":"10.1145/15922.15888","DOIUrl":"https://doi.org/10.1145/15922.15888","url":null,"abstract":"A program for the real-time display of computer animation on a bit-mapped raster display is presented. The differential compiler performs temporal domain image data compression using frame replenishment coding on successive frames of animation stored in memory as bitmaps and saves only the differences. A small run-time interpreter then retrieves and displays the differences in real-time to create the animated effect. This results in a significant reduction in storage requirements, and allows animation on general purpose computers which would otherwise be too slow or have insufficient memory. Frame creation is both device and method independent. An animation environment supports interactive editing capabilities, reconstructing any arbitrary desired frame for later modification. Frames can be added, modified, or deleted, and the animated sequence can be viewed at any point during the session. The compiler is automatically called as needed; its operation is transparent to the user. The compiler is described in detail, both in terms of data compression and the requirements of interactive animation editing.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83358744","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 illustrate two enhancements to procedural geometric models which allow autonomous procedures to jointly satisfy mutual constraints. One of the techniques adds communications paths between procedures which may affect one another. Conflicts are resolved by modifying communicating procedures as they execute.The second technique is a generalization of widely used subdivision procedures. The termination test of typical subdivision methods is replaced with a "transition" test. The subdivision procedure is augmented with a "script" in the form of a state transition table which controls the procedures' response to external events as well as to the normal termination conditions.In the examples we show how effective these techniques are building complex geometric models with very sparse input.
{"title":"Managing geometric complexity with enhanced procedural models","authors":"P. Amburn, E. Grant, T. Whitted","doi":"10.1145/15922.15907","DOIUrl":"https://doi.org/10.1145/15922.15907","url":null,"abstract":"We illustrate two enhancements to procedural geometric models which allow autonomous procedures to jointly satisfy mutual constraints. One of the techniques adds communications paths between procedures which may affect one another. Conflicts are resolved by modifying communicating procedures as they execute.The second technique is a generalization of widely used subdivision procedures. The termination test of typical subdivision methods is replaced with a \"transition\" test. The subdivision procedure is augmented with a \"script\" in the form of a state transition table which controls the procedures' response to external events as well as to the normal termination conditions.In the examples we show how effective these techniques are building complex geometric models with very sparse input.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"60 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88439356","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}
It is very time-consuming and expensive to create the graphical, highly-interactive styles of user interfaces that are increasingly common. User Interface Management Systems (UIMSs) attempt to make the creation of user interfaces easier, but most existing UIMSs cannot create the low-level interaction techniques (pop-up pull-down and fixed menus, on-screen "light buttons", scroll-bars, elaborate feedback mechanisms and animations, etc.) that are frequently used. This paper describes Peridot, a system that automatically creates the code for these user interfaces while the designer demonstrates to the system how the interface should look and work. Peridot uses rule-based inferencing so no programming by the designer is required, and Direct Manipulation techniques are used to create Direct Manipulation interfaces, which can make full use of a mouse and other input devices. This allows extremely rapid prototyping of user interfaces.
{"title":"Creating highly-interactive and graphical user interfaces by demonstration","authors":"B. Myers, W. Buxton","doi":"10.1145/15922.15914","DOIUrl":"https://doi.org/10.1145/15922.15914","url":null,"abstract":"It is very time-consuming and expensive to create the graphical, highly-interactive styles of user interfaces that are increasingly common. User Interface Management Systems (UIMSs) attempt to make the creation of user interfaces easier, but most existing UIMSs cannot create the low-level interaction techniques (pop-up pull-down and fixed menus, on-screen \"light buttons\", scroll-bars, elaborate feedback mechanisms and animations, etc.) that are frequently used. This paper describes Peridot, a system that automatically creates the code for these user interfaces while the designer demonstrates to the system how the interface should look and work. Peridot uses rule-based inferencing so no programming by the designer is required, and Direct Manipulation techniques are used to create Direct Manipulation interfaces, which can make full use of a mouse and other input devices. This allows extremely rapid prototyping of user interfaces.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73588872","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 developed for surface-fitting from sampled data. Surface-fitting is the process of constructing a compact representation to model the surface of an object based on a fairly large number of given data points. In our case, the data is obtained from a real object using an automatic three-dimensional digitizing system. The method is based on an adaptive subdivision approach, a technique previously used for the design and display of free-form curved surface objects. Our approach begins with a rough approximating surface and progressively refines it in successive steps in regions where the data is poorly approximated. The method has been implemented using a parametric piecewise bicubic Bernstein-Bézier surface possessing G1 geometric continuity. An advantage of this approach is that the refinement is essentially local reducing the computational requirements which permits the processing of large databases. Furthermore, the method is simple in concept, yet realizes efficient data compression. Some experimental results are given which show that the representation constructed by this method is faithful to the original database.
{"title":"An adaptive subdivision method for surface-fitting from sampled data","authors":"F. Schmitt, B. Barsky, Wen-Hui Du","doi":"10.1145/15922.15906","DOIUrl":"https://doi.org/10.1145/15922.15906","url":null,"abstract":"A method is developed for surface-fitting from sampled data. Surface-fitting is the process of constructing a compact representation to model the surface of an object based on a fairly large number of given data points. In our case, the data is obtained from a real object using an automatic three-dimensional digitizing system. The method is based on an adaptive subdivision approach, a technique previously used for the design and display of free-form curved surface objects. Our approach begins with a rough approximating surface and progressively refines it in successive steps in regions where the data is poorly approximated. The method has been implemented using a parametric piecewise bicubic Bernstein-Bézier surface possessing G1 geometric continuity. An advantage of this approach is that the refinement is essentially local reducing the computational requirements which permits the processing of large databases. Furthermore, the method is simple in concept, yet realizes efficient data compression. Some experimental results are given which show that the representation constructed by this method is faithful to the original database.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77333799","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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