|dc.description.abstract||This paper presents a methodology for sampling and rendering 3-dimensional (3D) volume data to give it the appearance of classical ink-and-paint techniques. Although tremendous strides have been made in the realm of realistic volume rendering, research on rendering techniques for non-photorealistic (NPR) images is limited and does not yield results that provides artists the ability to create and render volumes in a classical animation style. Currently, the industry standard is to render the volume using 3D volume data and the diffuse channel, or to provide a card and play an image sequence on the card.
This paper discusses a technique that allows for the non-photorealistic rendering of 3D volume data which can be used to sample and shade a variety of shapes to create a stylized render of a volume, similar to classical ink-and-paint techniques. This approach can be summarized in the following steps: (1) Scatter point data within 3D volume data based off of density values, or create a custom point cloud; (2) Ray cast from the camera to the hit position of the volume; (3) From the hit position of the ray, cast towards a direction (either towards a light for shading, or continue in the same direction for a headlamp effect); and (4) Tally and normalize the number of scattered points within a radius of the direction of said ray; then (5) Use this value to interpolate between the lit color of the volume and the background color.||en