This paper examines three methods, two existing and one new, for the generation of fractals based on recursive subdivision. Both existing methods are found to have defects, which are not present in the new method. A parallel processing algorithm is proposed for the rendering of height fields which is exact and distributes the load evenly between the processors. A method is described for the 'fan-tracing' of height fields to allow the realistic simulation of water reflections.
{"title":"The definition and rendering of terrain maps","authors":"G. Miller","doi":"10.1145/15922.15890","DOIUrl":"https://doi.org/10.1145/15922.15890","url":null,"abstract":"This paper examines three methods, two existing and one new, for the generation of fractals based on recursive subdivision. Both existing methods are found to have defects, which are not present in the new method. A parallel processing algorithm is proposed for the rendering of height fields which is exact and distributes the load evenly between the processors. A method is described for the 'fan-tracing' of height fields to allow the realistic simulation of water reflections.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"233 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79048323","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 power of a color space to perform well in interpolation problems such as anti-aliasing and smooth-shading is dependent on the topology of the color space as well as the number of elements it contains.We develop the Major-minor color space, which has a topology and representation that lends itself to simple anti-aliasing computations between elements of an arbitrary set of colors in an inexpensive frame store.
{"title":"Anti-aliasing in topological color spaces","authors":"Ken Turkowski","doi":"10.1145/15922.15920","DOIUrl":"https://doi.org/10.1145/15922.15920","url":null,"abstract":"The power of a color space to perform well in interpolation problems such as anti-aliasing and smooth-shading is dependent on the topology of the color space as well as the number of elements it contains.We develop the Major-minor color space, which has a topology and representation that lends itself to simple anti-aliasing computations between elements of an arbitrary set of colors in an inexpensive frame store.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88265405","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}
Constructive Solid Geometry (CSG) is a powerful way of describing solid objects for computer graphics and modeling. The surfaces of any primitive object (such as a cube, sphere or cylinder) can be approximated by polygons. Being abile to find the union, intersection or difference of these objects allows more interesting and complicated polygonal objects to be created. The algorithm presented here performs these set operations on objects constructed from convex polygons. These objects must bound a finite volume, but need not be convex. An object that results from one of these operations also contains only convex polygons, and bounds a finite volume; thus, it can be used in later combinations, allowing the generation of quite complicated objects. Our algorithm is robust and is presented in enough detail to be implemented.
{"title":"Constructive solid geometry for polyhedral objects","authors":"D. Laidlaw, W. B. Trumbore, J. Hughes","doi":"10.1145/15922.15904","DOIUrl":"https://doi.org/10.1145/15922.15904","url":null,"abstract":"Constructive Solid Geometry (CSG) is a powerful way of describing solid objects for computer graphics and modeling. The surfaces of any primitive object (such as a cube, sphere or cylinder) can be approximated by polygons. Being abile to find the union, intersection or difference of these objects allows more interesting and complicated polygonal objects to be created. The algorithm presented here performs these set operations on objects constructed from convex polygons. These objects must bound a finite volume, but need not be convex. An object that results from one of these operations also contains only convex polygons, and bounds a finite volume; thus, it can be used in later combinations, allowing the generation of quite complicated objects. Our algorithm is robust and is presented in enough detail to be implemented.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"84 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74226467","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}
Natural lighting models to date have been limited to calculation of direct sunlight. However, this paper proposes an improved model for natural lighting calculations that adequately considers both direct sunlight and scattered light caused by clouds and other forms of water vapor in the air. Such indirect natural light is termed skylight and can be an important factor when attempting to render realistic looking images as they might appear under overcast skies.In the proposed natural lighting model, the sky is considered to be a hemisphere with a large radius (called the sky dome) that acts as a source of diffuse light with nonuniform intensity. In order to adequately take into account the nonuniform intensity of such skylight, the sky dome is subdivided into bands. The light intensity within individual bands can be assumed to be transversely uniform and longitudinally nonuniform and therefore the total luminance emanating from each band can be calculated more accurately.The proposed method significantly improves the realism of natural lighting effects. Its advantages are particularly apparent when simulating lighting under an overcast sky or when rendering surfaces that fall within a shadow cast by an obstruction lit by direct sunlight.
{"title":"Continuous tone representation of three-dimensional objects illuminated by sky light","authors":"T. Nishita, E. Nakamae","doi":"10.1145/15922.15900","DOIUrl":"https://doi.org/10.1145/15922.15900","url":null,"abstract":"Natural lighting models to date have been limited to calculation of direct sunlight. However, this paper proposes an improved model for natural lighting calculations that adequately considers both direct sunlight and scattered light caused by clouds and other forms of water vapor in the air. Such indirect natural light is termed skylight and can be an important factor when attempting to render realistic looking images as they might appear under overcast skies.In the proposed natural lighting model, the sky is considered to be a hemisphere with a large radius (called the sky dome) that acts as a source of diffuse light with nonuniform intensity. In order to adequately take into account the nonuniform intensity of such skylight, the sky dome is subdivided into bands. The light intensity within individual bands can be assumed to be transversely uniform and longitudinally nonuniform and therefore the total luminance emanating from each band can be calculated more accurately.The proposed method significantly improves the realism of natural lighting effects. Its advantages are particularly apparent when simulating lighting under an overcast sky or when rendering surfaces that fall within a shadow cast by an obstruction lit by direct sunlight.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74349788","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 real-time shaded display of a solid model being milled by a cutting tool following an NC path is attained by the image-space Boolean subtraction of solid objects. The technique is suitable for implementation in microcode in a raster graphic display processor. Update rates of 10 cutting operations per second are typical.
{"title":"Real-time shaded NC milling display","authors":"Tim Van Hook","doi":"10.1145/15922.15887","DOIUrl":"https://doi.org/10.1145/15922.15887","url":null,"abstract":"The real-time shaded display of a solid model being milled by a cutting tool following an NC path is attained by the image-space Boolean subtraction of solid objects. The technique is suitable for implementation in microcode in a raster graphic display processor. Update rates of 10 cutting operations per second are typical.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84189973","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}
Although modeling natural phenomena is recognized as one of the greatest challenges of computer graphics, relatively little time has been spent on modeling ocean waves. The model presented in this paper is suitable for the rendering and animation of waves approaching and breaking on a sloping beach. Waveforms consist of a phase function which correctly produces wave refraction and other depth effects, and a wave profile which changes according to wave steepness and water depth. Particle systems are used to model the spray produced by wave breaking and collisions with obstacles. A scanline algorithm for displaying the wave surface is presented, along with a method of integrating separately rendered particle systems with other surfaces. Hidden surface removal for both waves and particles is done using a novel variation of the A-buffer technique. Methods of implementing the model are presented and compared with previous rendering techniques.
{"title":"Modeling waves and surf","authors":"D. Peachey","doi":"10.1145/15922.15893","DOIUrl":"https://doi.org/10.1145/15922.15893","url":null,"abstract":"Although modeling natural phenomena is recognized as one of the greatest challenges of computer graphics, relatively little time has been spent on modeling ocean waves. The model presented in this paper is suitable for the rendering and animation of waves approaching and breaking on a sloping beach. Waveforms consist of a phase function which correctly produces wave refraction and other depth effects, and a wave profile which changes according to wave steepness and water depth. Particle systems are used to model the spray produced by wave breaking and collisions with obstacles. A scanline algorithm for displaying the wave surface is presented, along with a method of integrating separately rendered particle systems with other surfaces. Hidden surface removal for both waves and particles is done using a novel variation of the A-buffer technique. Methods of implementing the model are presented and compared with previous rendering techniques.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85376109","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 two algorithms for the display of CSG-defined objects on Pixel-Powers, an extension of the Pixel-Planes logic-enhanced memory architecture, which calculates for each and every pixel on the screen (in parallel) the value of any quadratic function in the screen coordinates (x,y). The first algorithm restructures any CSG tree into an equivalent, but possibly larger, tree whose display can be achieved by the second algorithm. The second algorithm traverses the restructured tree and generates quadratic coefficients and opcodes for Pixel-Powers. These opcodes instruct Pixel-Powers to generate the boundaries of primitives and perform set operations using the standard Z-buffer algorithm.Several externally-supplied CSG data sets have been processed with the new tree-traversal algorithm and an associated Pixel-Powers simulator. The resulting images indicate that good results can be obtained very rapidly with the new system. For example, the commonly used MBB test part (at right) with 24 primitives is translated into approximately 1900 quadratic equations. On a Pixel-Powers system running at 10MHz (the speed at which our current Pixel-Planes memories run), the image should be rendered in about 7.5 milliseconds.
{"title":"Fast constructive-solid geometry display in the pixel-powers graphics system","authors":"Jack Goldfeather, J. Hultquist, H. Fuchs","doi":"10.1145/15922.15898","DOIUrl":"https://doi.org/10.1145/15922.15898","url":null,"abstract":"We present two algorithms for the display of CSG-defined objects on Pixel-Powers, an extension of the Pixel-Planes logic-enhanced memory architecture, which calculates for each and every pixel on the screen (in parallel) the value of any quadratic function in the screen coordinates (x,y). The first algorithm restructures any CSG tree into an equivalent, but possibly larger, tree whose display can be achieved by the second algorithm. The second algorithm traverses the restructured tree and generates quadratic coefficients and opcodes for Pixel-Powers. These opcodes instruct Pixel-Powers to generate the boundaries of primitives and perform set operations using the standard Z-buffer algorithm.Several externally-supplied CSG data sets have been processed with the new tree-traversal algorithm and an associated Pixel-Powers simulator. The resulting images indicate that good results can be obtained very rapidly with the new system. For example, the commonly used MBB test part (at right) with 24 primitives is translated into approximately 1900 quadratic equations. On a Pixel-Powers system running at 10MHz (the speed at which our current Pixel-Planes memories run), the image should be rendered in about 7.5 milliseconds.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86874797","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}
By integrating physical simulation, in the form of numerical fluid dynamics, with visual simulation, in the form of particle rendering, texture mapping and traditional polygonal modeling techniques, we have achieved a uniquely realistic and organic special effects sequence of a planetary atmospheric flow. This paper examines the selection, implementation, and application of these techniques, know collectively as VORTEX, to produce the moving images of the planet Jupiter in the film "2010." Details of the generation of the flow field and the fluid dynamic algorithms employed are presented, along with issues relating to the generation and updating of the atmospheric images. We also describe the integration of these techniques with an advanced computer graphics imaging system. The VORTEX system provides a fairly general solution to a class of imaging problems involving two-dimensional fluid flows, and we remark upon its application to other projects. VORTEX, as an example of the marriage of physical simulation to visual simulation, demonstrates the importance of computer graphics to the computational sciences and of the physical sciences to the field of computer graphics.
{"title":"Combining physical and visual simulation—creation of the planet Jupiter for the film “2010”","authors":"L. Yaeger, C. Upson, R. Myers","doi":"10.1145/15922.15895","DOIUrl":"https://doi.org/10.1145/15922.15895","url":null,"abstract":"By integrating physical simulation, in the form of numerical fluid dynamics, with visual simulation, in the form of particle rendering, texture mapping and traditional polygonal modeling techniques, we have achieved a uniquely realistic and organic special effects sequence of a planetary atmospheric flow. This paper examines the selection, implementation, and application of these techniques, know collectively as VORTEX, to produce the moving images of the planet Jupiter in the film \"2010.\" Details of the generation of the flow field and the fluid dynamic algorithms employed are presented, along with issues relating to the generation and updating of the atmospheric images. We also describe the integration of these techniques with an advanced computer graphics imaging system. The VORTEX system provides a fairly general solution to a class of imaging problems involving two-dimensional fluid flows, and we remark upon its application to other projects. VORTEX, as an example of the marriage of physical simulation to visual simulation, demonstrates the importance of computer graphics to the computational sciences and of the physical sciences to the field of computer graphics.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"2014 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78710159","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 consistent hierarchical data structure for the representation of vector data is presented. It makes use of a concept termed a line segment fragment to prevent data degradation under splitting or clipping of vector primitives. This means that the insertion and subsequent deletion (and vice versa) of a vector leaves the data unchanged. Vectors are represented exactly and not as digital approximations. The data is dynamically organized by use of simple probabilistic splitting and merging rules. The use of the structure for implementing a geographic information system is described. Algorithms for constructing and manipulating the structure are provided. Results of empirical tests comparing the structure to other representations in the literature are given.
{"title":"A consistent hierarchical representation for vector data","authors":"R. Nelson, H. Samet","doi":"10.1145/15922.15908","DOIUrl":"https://doi.org/10.1145/15922.15908","url":null,"abstract":"A consistent hierarchical data structure for the representation of vector data is presented. It makes use of a concept termed a line segment fragment to prevent data degradation under splitting or clipping of vector primitives. This means that the insertion and subsequent deletion (and vice versa) of a vector leaves the data unchanged. Vectors are represented exactly and not as digital approximations. The data is dynamically organized by use of simple probabilistic splitting and merging rules. The use of the structure for implementing a geographic information system is described. Algorithms for constructing and manipulating the structure are provided. Results of empirical tests comparing the structure to other representations in the literature are given.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84058438","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 technique is presented for deforming solid geometric models in a free-form manner. The technique can be used with any solid modeling system, such as CSG or B-rep. It can deform surface primitives of any type or degree: planes, quadrics, parametric surface patches, or implicitly defined surfaces, for example. The deformation can be applied either globally or locally. Local deformations can be imposed with any desired degree of derivative continuity. It is also possible to deform a solid model in such a way that its volume is preserved.The scheme is based on trivariate Bernstein polynomials, and provides the designer with an intuitive appreciation for its effects.
{"title":"Free-form deformation of solid geometric models","authors":"T. Sederberg, S. Parry","doi":"10.1145/15922.15903","DOIUrl":"https://doi.org/10.1145/15922.15903","url":null,"abstract":"A technique is presented for deforming solid geometric models in a free-form manner. The technique can be used with any solid modeling system, such as CSG or B-rep. It can deform surface primitives of any type or degree: planes, quadrics, parametric surface patches, or implicitly defined surfaces, for example. The deformation can be applied either globally or locally. Local deformations can be imposed with any desired degree of derivative continuity. It is also possible to deform a solid model in such a way that its volume is preserved.The scheme is based on trivariate Bernstein polynomials, and provides the designer with an intuitive appreciation for its effects.","PeriodicalId":20524,"journal":{"name":"Proceedings of the 13th annual conference on Computer graphics and interactive techniques","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1986-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82402813","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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