The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Carlos D Correa - One of the best experts on this subject based on the ideXlab platform.
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visibility histograms and visibility driven Transfer Functions
IEEE Transactions on Visualization and Computer Graphics, 2011Co-Authors: Carlos D CorreaAbstract:Direct volume rendering is an important tool for visualizing complex data sets. However, in the process of generating 2D images from 3D data, information is lost in the form of attenuation and occlusion. The lack of a feedback mechanism to quantify the loss of information in the rendering process makes the design of good Transfer Functions a difficult and time consuming task. In this paper, we present the general notion of visibility histograms, which are multidimensional graphical representations of the distribution of visibility in a volume-rendered image. In this paper, we explore the 1D and 2D Transfer Functions that result from intensity values and gradient magnitude. With the help of these histograms, users can manage a complex set of Transfer function parameters that maximize the visibility of the intervals of interest and provide high quality images of volume data. We present a semiautomated method for generating Transfer Functions, which progressively explores the Transfer function space toward the goal of maximizing visibility of important structures. Our methodology can be easily deployed in most visualization systems and can be used together with traditional 1D and 2D opacity Transfer Functions based on scalar values, as well as with other more sophisticated rendering algorithms.
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visibility driven Transfer Functions
IEEE Pacific Visualization Symposium, 2009Co-Authors: Carlos D CorreaAbstract:Direct volume rendering is an important tool for visualizing complex data sets. However, in the process of generating 2D images from 3D data, information is lost in the form of attenuation and occlusion. The lack of a feedback mechanism to quantify the loss of information in the rendering process makes the design of good Transfer Functions a difficult and time consuming task. In this paper, we present the notion of visibility-driven Transfer Functions, which are Transfer Functions that provide a good visibility of features of interest from a given viewpoint. To achieve this, we introduce visibility histograms. These histograms provide graphical cues that intuitively inform the user about the contribution of particular scalar values to the final image. By carefully manipulating the parameters of the opacity Transfer function, users can now maximize the visibility of the intervals of interest in a volume data set. Based on this observation, we also propose a semi-automated method for generating Transfer Functions, which progressively improves a Transfer function defined by the user, according to a certain importance metric. Now the user does not have to deal with the tedious task of making small changes to the Transfer function parameters, but now he/she can rely on the system to perform these searches automatically. Our methodology can be easily deployed in most visualization systems and can be used together with traditional 1D opacity Transfer Functions based on scalar values, as well as with multidimensional Transfer Functions and other more sophisticated rendering algorithms.
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PacificVis - Visibility-driven Transfer Functions
2009 IEEE Pacific Visualization Symposium, 2009Co-Authors: Carlos D Correa, Kwan-liu MaAbstract:Direct volume rendering is an important tool for visualizing complex data sets. However, in the process of generating 2D images from 3D data, information is lost in the form of attenuation and occlusion. The lack of a feedback mechanism to quantify the loss of information in the rendering process makes the design of good Transfer Functions a difficult and time consuming task. In this paper, we present the notion of visibility-driven Transfer Functions, which are Transfer Functions that provide a good visibility of features of interest from a given viewpoint. To achieve this, we introduce visibility histograms. These histograms provide graphical cues that intuitively inform the user about the contribution of particular scalar values to the final image. By carefully manipulating the parameters of the opacity Transfer function, users can now maximize the visibility of the intervals of interest in a volume data set. Based on this observation, we also propose a semi-automated method for generating Transfer Functions, which progressively improves a Transfer function defined by the user, according to a certain importance metric. Now the user does not have to deal with the tedious task of making small changes to the Transfer function parameters, but now he/she can rely on the system to perform these searches automatically. Our methodology can be easily deployed in most visualization systems and can be used together with traditional 1D opacity Transfer Functions based on scalar values, as well as with multidimensional Transfer Functions and other more sophisticated rendering algorithms.
C. Hansen - One of the best experts on this subject based on the ideXlab platform.
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Interactive volume rendering using multi-dimensional Transfer Functions and direct manipulation widgets
2005Co-Authors: J. Kniss, Gordon Kindlmann, C. HansenAbstract:Most direct volume renderings produced today employ one- dimensional Transfer Functions, which assign color and opacity to the volume based solely on the single scalar quantity which com- prises the dataset. Though they have not received widespread atten- tion, multi-dimensional Transfer Functions are a very effective way to extract specific material boundaries and convey subtle surface properties. However, identifying good Transfer Functions is difficult enough in one dimension, let alone two or three dimensions. This paper demonstrates an important class of three-dimensional Transfer Functions for scalar data (based on data value, gradient magnitude, and a second directional derivative), and describes a set of direct manipulation widgets which make specifying such Transfer func- tions intuitive and convenient. We also describe how to use modern graphics hardware to interactively render with multi-dimensional Transfer Functions. The Transfer Functions, widgets, and hardware combine to form a powerful system for interactive volume explo- ration
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gaussian Transfer Functions for multi field volume visualization
IEEE Visualization, 2003Co-Authors: J. Kniss, C. Hansen, Simon Premoze, M Ikits, Aaron Lefohn, Emil PraunAbstract:Volume rendering is a flexible technique for visualizing dense 3D volumetric datasets. A central element of volume rendering is the conversion between data values and observable quantities such as color and opacity. This process is usually realized through the use of Transfer Functions that are precomputed and stored in lookup tables. For multidimensional Transfer Functions applied to multivariate data, these lookup tables become prohibitively large. We propose the direct evaluation of a particular type of Transfer Functions based on a sum of Gaussians. Because of their simple form (in terms of number of parameters), these Functions and their analytic integrals along line segments can be evaluated efficiently on current graphics hardware, obviating the need for precomputed lookup tables. We have adopted these Transfer Functions because they are well suited for classification based on a unique combination of multiple data values that localize features in the Transfer function domain. We apply this technique to the visualization of several multivariate datasets (CT, cryosection) that are difficult to classify and render accurately at interactive rates using traditional approaches.
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Multidimensional Transfer Functions for interactive volume rendering
IEEE Transactions on Visualization and Computer Graphics, 2002Co-Authors: J. Kniss, Gordon Kindlmann, C. HansenAbstract:Most direct volume renderings produced today employ 1D Transfer Functions which assign color and opacity to the volume based solely on the single scalar quantity which comprises the data set. Though they have not received widespread attention, multi-dimensional Transfer Functions are a very effective way to extract materials and their boundaries for both scalar and multivariate data. However, identifying good Transfer Functions is difficult enough in 1D, let alone 2D or 3D. This paper demonstrates an important class of 3D Transfer Functions for scalar data, and describes the application of multi-dimensional Transfer Functions to multivariate data. We present a set of direct manipulation widgets that make specifying such Transfer Functions intuitive and convenient. We also describe how to use modern graphics hardware to both interactively render with multidimensional Transfer Functions and to provide interactive shadows for volumes. The Transfer Functions, widgets and hardware combine to form a powerful system for interactive volume exploration.
J. Kniss - One of the best experts on this subject based on the ideXlab platform.
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Interactive volume rendering using multi-dimensional Transfer Functions and direct manipulation widgets
2005Co-Authors: J. Kniss, Gordon Kindlmann, C. HansenAbstract:Most direct volume renderings produced today employ one- dimensional Transfer Functions, which assign color and opacity to the volume based solely on the single scalar quantity which com- prises the dataset. Though they have not received widespread atten- tion, multi-dimensional Transfer Functions are a very effective way to extract specific material boundaries and convey subtle surface properties. However, identifying good Transfer Functions is difficult enough in one dimension, let alone two or three dimensions. This paper demonstrates an important class of three-dimensional Transfer Functions for scalar data (based on data value, gradient magnitude, and a second directional derivative), and describes a set of direct manipulation widgets which make specifying such Transfer func- tions intuitive and convenient. We also describe how to use modern graphics hardware to interactively render with multi-dimensional Transfer Functions. The Transfer Functions, widgets, and hardware combine to form a powerful system for interactive volume explo- ration
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gaussian Transfer Functions for multi field volume visualization
IEEE Visualization, 2003Co-Authors: J. Kniss, C. Hansen, Simon Premoze, M Ikits, Aaron Lefohn, Emil PraunAbstract:Volume rendering is a flexible technique for visualizing dense 3D volumetric datasets. A central element of volume rendering is the conversion between data values and observable quantities such as color and opacity. This process is usually realized through the use of Transfer Functions that are precomputed and stored in lookup tables. For multidimensional Transfer Functions applied to multivariate data, these lookup tables become prohibitively large. We propose the direct evaluation of a particular type of Transfer Functions based on a sum of Gaussians. Because of their simple form (in terms of number of parameters), these Functions and their analytic integrals along line segments can be evaluated efficiently on current graphics hardware, obviating the need for precomputed lookup tables. We have adopted these Transfer Functions because they are well suited for classification based on a unique combination of multiple data values that localize features in the Transfer function domain. We apply this technique to the visualization of several multivariate datasets (CT, cryosection) that are difficult to classify and render accurately at interactive rates using traditional approaches.
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Multidimensional Transfer Functions for interactive volume rendering
IEEE Transactions on Visualization and Computer Graphics, 2002Co-Authors: J. Kniss, Gordon Kindlmann, C. HansenAbstract:Most direct volume renderings produced today employ 1D Transfer Functions which assign color and opacity to the volume based solely on the single scalar quantity which comprises the data set. Though they have not received widespread attention, multi-dimensional Transfer Functions are a very effective way to extract materials and their boundaries for both scalar and multivariate data. However, identifying good Transfer Functions is difficult enough in 1D, let alone 2D or 3D. This paper demonstrates an important class of 3D Transfer Functions for scalar data, and describes the application of multi-dimensional Transfer Functions to multivariate data. We present a set of direct manipulation widgets that make specifying such Transfer Functions intuitive and convenient. We also describe how to use modern graphics hardware to both interactively render with multidimensional Transfer Functions and to provide interactive shadows for volumes. The Transfer Functions, widgets and hardware combine to form a powerful system for interactive volume exploration.
A. Kawakami - One of the best experts on this subject based on the ideXlab platform.
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A realization method of Transfer Functions containing variable parameter
Proceedings of IECON'94 - 20th Annual Conference of IEEE Industrial Electronics, 1Co-Authors: A. KawakamiAbstract:Proposes a method for realizing Transfer Functions containing variable parameters, by the state-space method. By using this method, variable Transfer Functions (VTF) can be often realized with a minimal dimension. For the case that a minimal realization can not be obtained, the realization dimension can be reduced. >
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ISCAS - A realization method of the Transfer Functions containing variable parameter
Proceedings of IEEE International Symposium on Circuits and Systems - ISCAS '94, 1Co-Authors: A. KawakamiAbstract:In this paper, we propose a method for realizing Transfer Functions containing a variable parameter, by the state-space method. By using this method, variable Transfer Functions (VTF) can be often realized with a minimal dimension. In case that a minimal realization can not be obtained, the realization dimension can be fairly reduced. >
Aynur Unal - One of the best experts on this subject based on the ideXlab platform.
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Transfer Functions for nonlinear systems via Fourier-Borel transforms
1988. IEEE International Symposium on Circuits and Systems, 1Co-Authors: Sumer Can, Aynur UnalAbstract:It is demonstrated that the general response of nonlinear dynamical systems can be expressed in terms of their Transfer Functions in an analogous way to the linear systems. The Transfer Functions are defined as the generalized series for the response of the nonlinear dynamical system which is initially at rest and which is loaded by a unit step function. These Transfer Functions are obtainable through symbolic computer algebra. >
