Patent ID: 8040350

Claim:
A method of adaptive direct volume rendering, comprising: fragmenting a sampled 3-D dataset of a scalar field into a plurality of sub-volumes of different sizes, each sub-volume associated with a set of data value parameters characterizing the data value distribution of the scalar field within the sub-volume; defining an opacity transfer function that is dependent upon data values of the scalar field and an illumination model; selectively casting a plurality of rays from a 2-D image plane towards the sampled dataset, each ray having an initial ray energy and a cross-section; for each ray cast from a selected location on the 2-D image plane, selecting a subset of the plurality of sub-volumes for interaction with the ray; estimating the ray energy reflected by each sub-volume of the subset using the opacity transfer function and the illumination model; and summing the reflected ray energy as a pixel value at the selected location on the 2-D image plane; and estimating pixel values at other locations on the 2-D image plane using the pixel values at the selected locations wherein the step of selecting a subset of the plurality of sub-volumes for interacting with the ray includes: identifying a largest sub-volume along the ray path and its corresponding maximum and minimum data values; checking if the opacity transfer function varies monotonically between the maximum and minimum scalar field values; if the function does not vary monotonically, recursively identifying a smaller sub-volume along the ray path and its corresponding maximum and minimum data values; and checking if the opacity transfer function varies monotonically between the maximum and minimum scalar field values of the smaller sub-volume; and if the function does vary monotonically, calculating the amount of ray energy reflected by the sub-volume during its interaction with the ray wherein the step of selectively casting a plurality of rays from a 2-D image plane is performed by a computer processor.