A new technique is presented for the metamorphosis of one digital image into another. The approach gives the animator high-level control of the visual effect by providing natural feature-based specification and interaction. When used effectively, this technique can give the illusion that the photographed or computer generated subjects are transforming in a fluid, surrealistic, and often dramatic way. Comparisons with existing methods are drawn, and the advantages and disadvantage's of each are examined. The new method is then extended to accommodate keyframed transformations between image sequences for motion image work. Several examples are illustrated with resulting images.
{"title":"Feature-based image metamorphosis","authors":"Thaddeus Beier, Shawn Neely","doi":"10.1145/280811.281029","DOIUrl":"https://doi.org/10.1145/280811.281029","url":null,"abstract":"A new technique is presented for the metamorphosis of one digital image into another. The approach gives the animator high-level control of the visual effect by providing natural feature-based specification and interaction. When used effectively, this technique can give the illusion that the photographed or computer generated subjects are transforming in a fluid, surrealistic, and often dramatic way. Comparisons with existing methods are drawn, and the advantages and disadvantage's of each are examined. The new method is then extended to accommodate keyframed transformations between image sequences for motion image work. Several examples are illustrated with resulting images.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121134779","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}
New hierarchical solid modeling operations are developed, which simulate twisting, bending, tapering, or similar transformations of geometric objects. The chief result is that the normal vector of an arbitrarily deformed smooth surface can be calculated directly from the surface normal vector of the undeformed surface and a transformation matrix. Deformations are easily combined in a hierarchical structure, creating complex objects from simpler ones. The position vectors and normal vectors in the simpler objects are used to calculate the position and normal vectors in the more complex forms; each level in the deformation hierarchy requires an additional matrix multiply for the normal vector calculation. Deformations are important and highly intuitive operations which ease the control and rendering of large families of three-dimensional geometric shapes.
{"title":"Global and local deformations of solid primitives","authors":"A. Barr","doi":"10.1145/280811.280998","DOIUrl":"https://doi.org/10.1145/280811.280998","url":null,"abstract":"New hierarchical solid modeling operations are developed, which simulate twisting, bending, tapering, or similar transformations of geometric objects. The chief result is that the normal vector of an arbitrarily deformed smooth surface can be calculated directly from the surface normal vector of the undeformed surface and a transformation matrix. Deformations are easily combined in a hierarchical structure, creating complex objects from simpler ones. The position vectors and normal vectors in the simpler objects are used to calculate the position and normal vectors in the more complex forms; each level in the deformation hierarchy requires an additional matrix multiply for the normal vector calculation. Deformations are important and highly intuitive operations which ease the control and rendering of large families of three-dimensional geometric shapes.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134498103","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 method for producing computer shaded pictures ot curved surfaces. Three-dimensional curved patches are used, a~ contrasted with conventional methods using polygons. The method subdivides a patch into successively smaller subpatches until a subpatch is as small as a raster-element, at which time it can be displayed. In general, this method could be very time consuming because of the great number of subdivisions that must take place; however, there is at least one very useful class of patches-the bicubic patch-that can be subdivided very quickly. Pictures produced with the method accurately portray the shading and silhouette of curved surfaces. In addition, photographs can be "mapped" onto patches thus providing a means for putting texture on computer generated pictures.
{"title":"Computer display of curved surfaces","authors":"E. Catmull","doi":"10.1145/280811.280920","DOIUrl":"https://doi.org/10.1145/280811.280920","url":null,"abstract":"This paper presents a method for producing computer shaded pictures ot curved surfaces. Three-dimensional curved patches are used, a~ contrasted with conventional methods using polygons. The method subdivides a patch into successively smaller subpatches until a subpatch is as small as a raster-element, at which time it can be displayed. In general, this method could be very time consuming because of the great number of subdivisions that must take place; however, there is at least one very useful class of patches-the bicubic patch-that can be subdivided very quickly. Pictures produced with the method accurately portray the shading and silhouette of curved surfaces. In addition, photographs can be \"mapped\" onto patches thus providing a means for putting texture on computer generated pictures.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116676372","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, Shenchang Chen, J. R. Wallace, D. Greenberg
A reformulated radiosity algorithm is presented that produces initial images in time linear to the number of patches. The enormous memory costs of the radiosity algorithm are also eliminated by computing form-factors on-the-fly. The technique is based on the approach of rendering by progressive refinement. The algorithm provides a useful solution almost immediately which progresses gracefully and continuously to the complete radiosity solution. In this way the competing demands of realism and interactivity are accommodated. The technique brings the use of radiosity for interactive rendering within reach and has implications for the use and development of current and future graphics workstations.
{"title":"A progressive refinement approach to fast radiosity image generation","authors":"Michael F. Cohen, Shenchang Chen, J. R. Wallace, D. Greenberg","doi":"10.1145/280811.280990","DOIUrl":"https://doi.org/10.1145/280811.280990","url":null,"abstract":"A reformulated radiosity algorithm is presented that produces initial images in time linear to the number of patches. The enormous memory costs of the radiosity algorithm are also eliminated by computing form-factors on-the-fly. The technique is based on the approach of rendering by progressive refinement. The algorithm provides a useful solution almost immediately which progresses gracefully and continuously to the complete radiosity solution. In this way the competing demands of realism and interactivity are accommodated. The technique brings the use of radiosity for interactive rendering within reach and has implications for the use and development of current and future graphics workstations.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124622177","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 research described in this paper addresses the problems associated with the design of systems for efficiently producing computer-generated pictures and picture sequences of very complex, three-dimensional environments. The thesis of the research is that the geometric structure inherent in the definition of the shapes of three-dimensional objects and environments must be used not just to define their relative motion and placement but also to assist in solving many other problems of systems for producing pictures by computer.The implications are that by using an extension of traditional structure information, or a geometric hierarchy, five significant improvements to current techniques are possible. First, the range of complexity of an environment is greatly increased while the visible complexity of any given scene is kept within a fixed upper limit. Second, a meaningful way is provided to vary the amount of detail presented in a scene both according to the screen area occupied by the objects in the scene and according to camera and object motions. Third, by using the geometric hierarchy, "clipping" becomes a very fast logarithmic search for the resolvable parts of the environment within the field-of-view. Fourth, by using this positional hierarchy in conjunction with a storage hierarchy of the sort used in virtual memory computing systems, frame-to-frame coherence and clipping define a graphical "working set", or fraction of the total structure that should be present in primary store for immediate access by the visible-surface algorithms. Finally, the proposed structural framework suggests a new recursive descent visible-surface algorithm in which the computation time grows almost linearly with a scene's visible complexity rather than as a worse than linear function of its object-space complexity.
{"title":"Hierarchical geometric models for visible surface algorithms","authors":"James H. Clark","doi":"10.1145/280811.280921","DOIUrl":"https://doi.org/10.1145/280811.280921","url":null,"abstract":"The research described in this paper addresses the problems associated with the design of systems for efficiently producing computer-generated pictures and picture sequences of very complex, three-dimensional environments. The thesis of the research is that the geometric structure inherent in the definition of the shapes of three-dimensional objects and environments must be used not just to define their relative motion and placement but also to assist in solving many other problems of systems for producing pictures by computer.The implications are that by using an extension of traditional structure information, or a geometric hierarchy, five significant improvements to current techniques are possible. First, the range of complexity of an environment is greatly increased while the visible complexity of any given scene is kept within a fixed upper limit. Second, a meaningful way is provided to vary the amount of detail presented in a scene both according to the screen area occupied by the objects in the scene and according to camera and object motions. Third, by using the geometric hierarchy, \"clipping\" becomes a very fast logarithmic search for the resolvable parts of the environment within the field-of-view. Fourth, by using this positional hierarchy in conjunction with a storage hierarchy of the sort used in virtual memory computing systems, frame-to-frame coherence and clipping define a graphical \"working set\", or fraction of the total structure that should be present in primary store for immediate access by the visible-surface algorithms. Finally, the proposed structural framework suggests a new recursive descent visible-surface algorithm in which the computation time grows almost linearly with a scene's visible complexity rather than as a worse than linear function of its object-space complexity.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"196 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132516748","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}
Described is a procedure for executing a visible surface algorithm in a new multi-microprocessor system which utilizes distributed image and depth (“Z”) buffers. It is shown that despite image distribution over a large number of processing and memory units, object coherence can still be maintained and used to reduce the number of calculations needed to generate a continuous-tone visible surface image.
{"title":"Distributing a visible surface algorithm over multiple processors","authors":"H. Fuchs","doi":"10.1145/280811.281020","DOIUrl":"https://doi.org/10.1145/280811.281020","url":null,"abstract":"Described is a procedure for executing a visible surface algorithm in a new multi-microprocessor system which utilizes distributed image and depth (“Z”) buffers. It is shown that despite image distribution over a large number of processing and memory units, object coherence can still be maintained and used to reduce the number of calculations needed to generate a continuous-tone visible surface image.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123424339","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 mapping of images onto surfaces may substantially increase the realism and information content of computer-generated imagery. The projection of a flat source image onto a curved surface may involve sampling difficulties, however, which are compounded as the view of the surface changes. As the projected scale of the surface increases, interpolation between the original samples of the source image is necessary; as the scale is reduced, approximation of multiple samples in the source is required. Thus a constantly changing sampling window of view-dependent shape must traverse the source image. To reduce the computation implied by these requirements, a set of prefiltered source images may be created. This approach can be applied to particular advantage in animation, where a large number of frames using the same source image must be generated. This paper advances a “pyramidal parametric” prefiltering and sampling geometry which minimizes aliasing effects and assures continuity within and between target images. Although the mapping of texture onto surfaces is an excellent example of the process and provided the original motivation for its development, pyramidal parametric data structures admit of wider application. The aliasing of not only surface texture, but also highlights and even the surface representations themselves, may be minimized by pyramidal parametric means.
{"title":"Pyramidal parametrics","authors":"Lance Williams","doi":"10.1145/280811.280977","DOIUrl":"https://doi.org/10.1145/280811.280977","url":null,"abstract":"The mapping of images onto surfaces may substantially increase the realism and information content of computer-generated imagery. The projection of a flat source image onto a curved surface may involve sampling difficulties, however, which are compounded as the view of the surface changes. As the projected scale of the surface increases, interpolation between the original samples of the source image is necessary; as the scale is reduced, approximation of multiple samples in the source is required. Thus a constantly changing sampling window of view-dependent shape must traverse the source image. To reduce the computation implied by these requirements, a set of prefiltered source images may be created. This approach can be applied to particular advantage in animation, where a large number of frames using the same source image must be generated. This paper advances a “pyramidal parametric” prefiltering and sampling geometry which minimizes aliasing effects and assures continuity within and between target images. Although the mapping of texture onto surfaces is an excellent example of the process and provided the original motivation for its development, pyramidal parametric data structures admit of wider application. The aliasing of not only surface texture, but also highlights and even the surface representations themselves, may be minimized by pyramidal parametric means.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125273190","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}
Line drawings are the most common type of rendering used to convey geometrical description. This is due to the economy of preparing such drawings and the great information density obtainable. On a pure line drawing, that is where no attempt is made to specify or suggest shadows, tone or color, the lines rendered are either the intersection curves of surfaces or the contour curves of surfaces. The nature of these curves are adequately discussed in the literature 1 and in a previous report.2 In order to convey a realistic impression of an object or an assembly of objects, the segments of lines which cannot be seen by an observer are not drawn or are drawn dashed. Without specification of visibility a drawing is ambiguous. This paper presents a recently developed scheme for the determination of visibility in a line drawing which enables comparitively high speed calculation and excellent resolution.
{"title":"The notion of quantitative invisibility and the machine rendering of solids","authors":"Arthur Appel","doi":"10.1145/280811.280916","DOIUrl":"https://doi.org/10.1145/280811.280916","url":null,"abstract":"Line drawings are the most common type of rendering used to convey geometrical description. This is due to the economy of preparing such drawings and the great information density obtainable. On a pure line drawing, that is where no attempt is made to specify or suggest shadows, tone or color, the lines rendered are either the intersection curves of surfaces or the contour curves of surfaces. The nature of these curves are adequately discussed in the literature 1 and in a previous report.2 In order to convey a realistic impression of an object or an assembly of objects, the segments of lines which cannot be seen by an observer are not drawn or are drawn dashed. Without specification of visibility a drawing is ambiguous. This paper presents a recently developed scheme for the determination of visibility in a line drawing which enables comparitively high speed calculation and excellent resolution.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116910498","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 papper deals with the problem of attaining real-time generation and display of half-tone perspective pictures. The FORTRAN IV program which produces the picture generation simplifies the input require of the user to obtain a given view of an object. Freedom in specifying both the orientation of the object and view point allows complete control over the perspective. The hidden line algorithm utilizes the order in which triangles enter from one scan line to the next and greatly reduce s the amount of scan line computations. With this algorithm, real-time picture generation becomes more of a possibility and real-time display a near-future reality.
{"title":"Real-time display of computer generated half-tone perspective pictures","authors":"G. Romney, Gary S. Watkins, D. C. Evans","doi":"10.1145/280811.281011","DOIUrl":"https://doi.org/10.1145/280811.281011","url":null,"abstract":"This papper deals with the problem of attaining real-time generation and display of half-tone perspective pictures. The FORTRAN IV program which produces the picture generation simplifies the input require of the user to obtain a given view of an object. Freedom in specifying both the orientation of the object and view point allows complete control over the perspective. The hidden line algorithm utilizes the order in which triangles enter from one scan line to the next and greatly reduce s the amount of scan line computations. With this algorithm, real-time picture generation becomes more of a possibility and real-time display a near-future reality.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115076195","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}
Algorithms for adaptive, tapered quantization of color images are described. The research is motivated by the desire to display high-quality reproductions of color images with small frame buffers. It is demonstrated that many color images which would normally require a frame buffer having 15 bits per pixel can be quantized to 8 or fewer bits per pixel with little subjective degradation. In most cases, the resulting images look significantly better than those made with uniform quantization. The color image quantization task is broken into four phases: 1) Sampling the original image for color statistics 2) Choosing a colormap based on the color statistics 3) Mapping original colors to their nearest neighbors in the colormap 4) Quantizing and redrawing the original image (with optional dither). Several algorithms for each of phases 2-4 are described, and images created by each given.
{"title":"Color image quantization for frame buffer display","authors":"Paul S. Heckbert","doi":"10.1145/280811.281025","DOIUrl":"https://doi.org/10.1145/280811.281025","url":null,"abstract":"Algorithms for adaptive, tapered quantization of color images are described. The research is motivated by the desire to display high-quality reproductions of color images with small frame buffers. It is demonstrated that many color images which would normally require a frame buffer having 15 bits per pixel can be quantized to 8 or fewer bits per pixel with little subjective degradation. In most cases, the resulting images look significantly better than those made with uniform quantization. The color image quantization task is broken into four phases: 1) Sampling the original image for color statistics 2) Choosing a colormap based on the color statistics 3) Mapping original colors to their nearest neighbors in the colormap 4) Quantizing and redrawing the original image (with optional dither). Several algorithms for each of phases 2-4 are described, and images created by each given.","PeriodicalId":236803,"journal":{"name":"Seminal graphics: pioneering efforts that shaped the field","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124637923","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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