Hewlett-Packard Company

Russell Huonder

Hasan Shahzad Naqvi

Barthold Lichtenbelt

A ray transform method for performing 3D spacial volume transformation for perspective view rendering of a volume data set on a 2D graphics display. A backward mapping approach is used whereby each destination point along a ray is transformed and resampled from the source. The rays converge at the center of projection, or the eye pont, from the projection plane for the perspective view desired. Each ray has a unique ray transform matrix which is combined with an orthographic model view matrix to yield a combined inverse matrix. The floating point values of the combined inverse matrix are coded into a 32 bit fixed point format having 16 bits of scalar and 16 bits of fraction. Once this coding has been done, then transforming consecutive points along a destination ray becomes simple integer adds. The method supports two resampling techniques, nearest neighbor and trilinear interpolation.

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Ft. Collins, CO, United States of America

Russell Huonder