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Frequency Analysis of Gradient Estimators in Volume Rendering

Bentum, Mark J.; Lichtenbelt, Barthold B.; Malzbender, Tom



Abstract: In volume rendering gradient information is used to classify and color samples along a ray. In this paper we present an analysis of the theoretically ideal gradient estimator and compare some commonly used gradient estimators with the ideal estimator. A new method is presented to calculate the gradient on an arbitrary position, using the derivative of the interpolation filter as the basis for the new gradient filter. As an example we will discuss the use of the derivative of the cubic spline. A comparison will be made showing the differences with other methods. Computational efficiency can be realized since parts of the interpolation computation can be leveraged in the gradient estimation.

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