Mastering Transfer Function Specification by using VolumePro Technology


Andreas H. König and Eduard M. Gröller
Institute of Computer Graphics
Vienna University of Technology
Karlsplatz 13
A-1040 Vienna



A new user-interface paradigm for the specification of transfer functions is presented. The specification is usually a difficult task as mapping information for a number of different domains (data range, color, opacity, etc.) has to be defined. In the presented approach, the definition of the mapping information can be realized independently for each property domain. A set of specification tools is provided for each domain, enabling users with different levels of experience or demanding time restrictions to choose an appropriate approach for their needs. Real-time feedback during the manipulation of parameters has been proven to be crucial to the specification. An interactive direct-volume-rendering display is realized by utilizing dedicated hardware acceleration.
Keywords: Volume Visualization, Transfer Function Specification, VolumePro ray-casting system


Download the paper (.pdf, 3.5MB).

Figures in the paper

Figure 1: Two contributions are combined for the visualization. Parameters for the dimensions of the transfer function (data range, color, and opacity) are defined independently.
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Figure 2: Real-time feedback for all modifications by the user is provided by a rendering window, using VolumePro technology for the calculation of the direct volume rendered image.
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Figure 3: Different peak shapes (from top to bottom): trapezoid, tent, box, and ramp.
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Figure 4: Specification of contributions from the range of data values.
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Figure 6: User interface for the combination of ``colored peaks'' by assigning opacities.
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Figure 5: Specification of contributions from the range of colors.
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Figure 7: Specification of a transfer function with three contributions.
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Institute of Computer Graphics / Visualization and Animation Group / Research

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