D. Bartz, Benjamin Schnaidt, Jirko Cernik, L. Gauckler, J. Fischer, Á. Río
Volume data is usually generated by measuring devices (eg. CT scanners, MRI scanners), mathematical functions (eg., Marschner/Lobb function), or by simulations. While all these sources typically generate 12 bit integer or floating point representations, commonly used displays are only capable of handling 8 bit gray or color levels. In a typical medical scenario, a 3D scanner will generate a 12 bit dataset, from which a subrange of the active full accuracy data range of 0 up to 4096 voxel values will be downsampled to an 8 bit per-voxel accuracy. This downsampling is usually achieved by a linear mapping operation and by clipping of value ranges left and right of the chosen subrange.In this paper, we propose a novel windowing operation that is based on methods from high dynamic range image mapping. With this method, the contrast of mapped 8 bit volume datasets is significantly enhanced, in particular if the imaging modality allows for a high tissue differentiation (eg., MRI). Thus, it also allows better and easier segmentation and classification. We demonstrate the improved contrast with different error metrics and a perception-driven image difference to indicate differences between three different high dynamic range operators.
{"title":"Volumetric high dynamic range windowing for better data representation","authors":"D. Bartz, Benjamin Schnaidt, Jirko Cernik, L. Gauckler, J. Fischer, Á. Río","doi":"10.1145/1108590.1108612","DOIUrl":"https://doi.org/10.1145/1108590.1108612","url":null,"abstract":"Volume data is usually generated by measuring devices (eg. CT scanners, MRI scanners), mathematical functions (eg., Marschner/Lobb function), or by simulations. While all these sources typically generate 12 bit integer or floating point representations, commonly used displays are only capable of handling 8 bit gray or color levels. In a typical medical scenario, a 3D scanner will generate a 12 bit dataset, from which a subrange of the active full accuracy data range of 0 up to 4096 voxel values will be downsampled to an 8 bit per-voxel accuracy. This downsampling is usually achieved by a linear mapping operation and by clipping of value ranges left and right of the chosen subrange.In this paper, we propose a novel windowing operation that is based on methods from high dynamic range image mapping. With this method, the contrast of mapped 8 bit volume datasets is significantly enhanced, in particular if the imaging modality allows for a high tissue differentiation (eg., MRI). Thus, it also allows better and easier segmentation and classification. We demonstrate the improved contrast with different error metrics and a perception-driven image difference to indicate differences between three different high dynamic range operators.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127753965","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 an interactive modelling technique, which reconstructs three-dimensional objects from user-drawn two-dimensional strokes. We first extract a skeleton from the 2D contour, and the skeleton is used to define an implicit surface that fits the 2D contour. The reconstructed 3D shape has a natural aspect, it is very smooth and can easily be edited and modified using strokes or performing operations on the skeleton. This method is very accessible for non-specialist users and it allows fast and easy shape prototyping.
{"title":"Interactive modelling from sketches using spherical implicit functions","authors":"Ileana Anca Alexe, V. Gaildrat, L. Barthe","doi":"10.1145/1029949.1029953","DOIUrl":"https://doi.org/10.1145/1029949.1029953","url":null,"abstract":"We present an interactive modelling technique, which reconstructs three-dimensional objects from user-drawn two-dimensional strokes. We first extract a skeleton from the 2D contour, and the skeleton is used to define an implicit surface that fits the 2D contour. The reconstructed 3D shape has a natural aspect, it is very smooth and can easily be edited and modified using strokes or performing operations on the skeleton. This method is very accessible for non-specialist users and it allows fast and easy shape prototyping.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124557848","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}
F. Struck, Christian-A. Bohn, Sebastian Schmidt, V. Helzle
The demand for realistic human characters is driven by interactive application developers worldwide. The look of 3D models in real time graphics is efficiently improved by powerful shader techniques. Today a common technique consists of a simple lighting model combined with textures, which have precalculated illumination included. In this paper we will give an overview of the most recent techniques in skin shading. We present a multifaced implementation of shading techniques by efficiently combining various approaches. Therefore we will explain physical and anatomical backgrounds and refer to relevant papers. In our opinion, this work is a valuable reference assist shader developers in their implementations and adaptions on recent and future graphic hardware.
{"title":"Realistic shading of human skin in real time","authors":"F. Struck, Christian-A. Bohn, Sebastian Schmidt, V. Helzle","doi":"10.1145/1029949.1029967","DOIUrl":"https://doi.org/10.1145/1029949.1029967","url":null,"abstract":"The demand for realistic human characters is driven by interactive application developers worldwide. The look of 3D models in real time graphics is efficiently improved by powerful shader techniques. Today a common technique consists of a simple lighting model combined with textures, which have precalculated illumination included. In this paper we will give an overview of the most recent techniques in skin shading. We present a multifaced implementation of shading techniques by efficiently combining various approaches. Therefore we will explain physical and anatomical backgrounds and refer to relevant papers. In our opinion, this work is a valuable reference assist shader developers in their implementations and adaptions on recent and future graphic hardware.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114349288","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}
Application services are fundamental network components that allow organizations the ability to operate efficiently. It has become essential for organizations to monitor the performance of these critical applications. Traditional network analysis tools, however, cannot cope with the size of today's network infrastructures and the volume of network data generated. The goal of this paper is to discuss the development of a visualisation system, called AppVis, that uses information visualisation techniques which are novel to this domain. This system will enable UPE to effectively visualise the application delay performance of the ITS application implemented on the network.
{"title":"The visualisation of application delay metrics for a customer network","authors":"J. Wesson, D. Greunen, Justin Rademan","doi":"10.1145/1029949.1029975","DOIUrl":"https://doi.org/10.1145/1029949.1029975","url":null,"abstract":"Application services are fundamental network components that allow organizations the ability to operate efficiently. It has become essential for organizations to monitor the performance of these critical applications. Traditional network analysis tools, however, cannot cope with the size of today's network infrastructures and the volume of network data generated. The goal of this paper is to discuss the development of a visualisation system, called AppVis, that uses information visualisation techniques which are novel to this domain. This system will enable UPE to effectively visualise the application delay performance of the ITS application implemented on the network.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124496725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper we concentrate on an optical effect well-suited for architectural or game-related renderings: glossy reflections on planar surfaces. We demonstrate a physically reasonable approximation of glossy reflections at slightly imperfect reflecting surfaces --- e.g. most floors --- that can be implemented at minimal performance penalty when compared to perfect reflections. An evaluation of our implementation using only standard graphic API functions in OpenGL 1.2 concludes the paper.
{"title":"Real-time glossy reflections on planar surfaces","authors":"A. Fuhrmann, R. Tobler, S. Maierhofer","doi":"10.1145/1029949.1029966","DOIUrl":"https://doi.org/10.1145/1029949.1029966","url":null,"abstract":"In this paper we concentrate on an optical effect well-suited for architectural or game-related renderings: glossy reflections on planar surfaces. We demonstrate a physically reasonable approximation of glossy reflections at slightly imperfect reflecting surfaces --- e.g. most floors --- that can be implemented at minimal performance penalty when compared to perfect reflections. An evaluation of our implementation using only standard graphic API functions in OpenGL 1.2 concludes the paper.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122518014","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}
J. Stumpfel, C. Tchou, Andrew Jones, Tim Hawkins, Andreas Wenger, P. Debevec
We present a technique for capturing the extreme dynamic range of natural illumination environments that include the sun and sky, which has presented a challenge for traditional high dynamic range photography processes. We find that through careful selection of exposure times, aperture, and neutral density filters that this full range can be covered in seven exposures with a standard digital camera. We discuss the particular calibration issues such as lens vignetting, infrared sensitivity, and spectral transmission of neutral density filters which must be addressed. We present an adaptive exposure range adjustment technique for minimizing the number of exposures necessary. We demonstrate our results by showing time-lapse renderings of a complex scene illuminated by high-resolution, high dynamic range natural illumination environments.
{"title":"Direct HDR capture of the sun and sky","authors":"J. Stumpfel, C. Tchou, Andrew Jones, Tim Hawkins, Andreas Wenger, P. Debevec","doi":"10.1145/1029949.1029977","DOIUrl":"https://doi.org/10.1145/1029949.1029977","url":null,"abstract":"We present a technique for capturing the extreme dynamic range of natural illumination environments that include the sun and sky, which has presented a challenge for traditional high dynamic range photography processes. We find that through careful selection of exposure times, aperture, and neutral density filters that this full range can be covered in seven exposures with a standard digital camera. We discuss the particular calibration issues such as lens vignetting, infrared sensitivity, and spectral transmission of neutral density filters which must be addressed. We present an adaptive exposure range adjustment technique for minimizing the number of exposures necessary. We demonstrate our results by showing time-lapse renderings of a complex scene illuminated by high-resolution, high dynamic range natural illumination environments.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127678710","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 describe our experience with collision in signing avatars -- that is, avatars which are required to execute Sign Language. We present a generalized high-level automata-based model for collision avoidance in signing avatars, and illustrate it with an application of a fingerspelling hand for the International Sign Alphabet.
{"title":"Implementation experience with collision avoidance in signing avatars","authors":"L. V. Zijl, L. Raitt","doi":"10.1145/1029949.1029959","DOIUrl":"https://doi.org/10.1145/1029949.1029959","url":null,"abstract":"We describe our experience with collision in signing avatars -- that is, avatars which are required to execute Sign Language. We present a generalized high-level automata-based model for collision avoidance in signing avatars, and illustrate it with an application of a fingerspelling hand for the International Sign Alphabet.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123418182","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}
Usually the software for textile visualization uses ideal model based on simplified structure assumptions that may not be in a good agreement with reality. Real model reconstructs a small volume of structure from 2D parallel cuts. Proposed virtual model joins both the models. In general, any structure parameter consists of two parts: fixed and variable. Specific statistical methods make possible to determine or generate both the components, if there are many photographs of random cuts. The correct virtual model allows generating many structures that can exist in reality. Ideal and real models were realized, the virtual model is proposed. Both the realized models use virtual reality, VRML, for structure visualization. Because of its simplicity, ideal model allows the use of many VRML methods: small cylinders, extrusion approach, small surfaces. Experiment is the base of real model. Space structure is reconstructed from the yarn boundaries that are on photographs of parallel equidistant cuts. In the case of simple structure the comparison of real and ideal model shows that the ideal model with proper parameters is close to reality.
{"title":"Ideal, real and virtual textile structure modelling and visualization","authors":"M. Kosek, T. Mikolanda, B. Koskova","doi":"10.1145/1029949.1029957","DOIUrl":"https://doi.org/10.1145/1029949.1029957","url":null,"abstract":"Usually the software for textile visualization uses ideal model based on simplified structure assumptions that may not be in a good agreement with reality. Real model reconstructs a small volume of structure from 2D parallel cuts. Proposed virtual model joins both the models. In general, any structure parameter consists of two parts: fixed and variable. Specific statistical methods make possible to determine or generate both the components, if there are many photographs of random cuts. The correct virtual model allows generating many structures that can exist in reality.\u0000 Ideal and real models were realized, the virtual model is proposed. Both the realized models use virtual reality, VRML, for structure visualization. Because of its simplicity, ideal model allows the use of many VRML methods: small cylinders, extrusion approach, small surfaces. Experiment is the base of real model. Space structure is reconstructed from the yarn boundaries that are on photographs of parallel equidistant cuts. In the case of simple structure the comparison of real and ideal model shows that the ideal model with proper parameters is close to reality.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130890495","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 argues that the concepts of immersion and realism in presence research can be reconceived respectively as the information load which a display presents about an environment, and the expectations which a user has for that environment. From this perspective, non-immersive, non-realistic environments can be conceived as having great possibilities for producing presence, as additional information about the environment can be displayed in iconic, non-diagetic or other non-realistic forms. This technique will not violate the users' expectations of what is possible in such an environment provided that those expectations about the environment as well as the users' degree of media literacy are taken into account.
{"title":"How is presence in non-immersive, non-realistic virtual environments possible?","authors":"David Nunez","doi":"10.1145/1029949.1029964","DOIUrl":"https://doi.org/10.1145/1029949.1029964","url":null,"abstract":"This paper argues that the concepts of immersion and realism in presence research can be reconceived respectively as the information load which a display presents about an environment, and the expectations which a user has for that environment. From this perspective, non-immersive, non-realistic environments can be conceived as having great possibilities for producing presence, as additional information about the environment can be displayed in iconic, non-diagetic or other non-realistic forms. This technique will not violate the users' expectations of what is possible in such an environment provided that those expectations about the environment as well as the users' degree of media literacy are taken into account.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128823169","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}
Genealogical information systems (GIS) typically contain large amounts of information about families and relationships between family members. Most existing GIS have textual, form-based interfaces for searching and browsing family information. These interfaces do not support dynamic browsing and manipulation of family trees. This paper discusses the design and development of a novel interface, called ZoomTree, for WINGIS (the GIS developed at UPE), to facilitate dynamic exploration and browsing of family tree information.
{"title":"A ZoomTree interface for searching genealogical information","authors":"J. Wesson, M. D. Plessis, Craig Oosthuizen","doi":"10.1145/1029949.1029974","DOIUrl":"https://doi.org/10.1145/1029949.1029974","url":null,"abstract":"Genealogical information systems (GIS) typically contain large amounts of information about families and relationships between family members. Most existing GIS have textual, form-based interfaces for searching and browsing family information. These interfaces do not support dynamic browsing and manipulation of family trees. This paper discusses the design and development of a novel interface, called ZoomTree, for WINGIS (the GIS developed at UPE), to facilitate dynamic exploration and browsing of family tree information.","PeriodicalId":325699,"journal":{"name":"International Conference on Computer Graphics, Virtual Reality, Visualisation and Interaction in Africa","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116145244","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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