We present a method for generating procedural volumetric fire in real time. By combining curve-based volumetric free-form deformation, hardware-accelerated volumetric rendering and Improved Perlin Noise or M-Noise we are able to render a vibrant and uniquely animated volumetric fire that supports bi-directional environmental macro-level interactivity. Our system is easily customizable by content artists. The fire is animated both on the macro and micro levels. Macro changes are controlled either by a prescripted sequence of movements, or by a realistic particle simulation that takes into account movement, wind, high-energy particle dispersion and thermal buoyancy. Micro fire effects such as individual flame shape, location, and flicker are generated in a pixel shader using three- to four-dimensional Improved Perlin Noise or M-Noise (depending on hardware limitations and performance requirements). Our method supports efficient collision detection, which, when combined with a sufficiently intelligent particle simulation, enables real-time bi-directional interaction between the fire and its environment. The result is a three-dimensional procedural fire that is easily designed and animated by content artists, supports dynamic interaction, and can be rendered in real time.

We present a new method for topological segmentation in steady three-dimensional vector fields. Depending on desired properties, the algorithm replaces the original vector field by a derived segmented data set, which is utilized to produce separating surfaces in the vector field. We define the concept of a segmented data set, develop methods that produce the segmented data by sampling the vector field with streamlines, and describe algorithms that generate the separating surfaces. This method is applied to generate local separatrices in the field, defined by a movable boundary region placed in the field. The resulting partitions can be visualized using standard techniques for a visualization of a vector field at a higher level of abstraction.

This paper presents a new algorithm for the calculation of stream surfaces for tetrahedral grids. It propagates the surface through the tetrahedra, one at a time, calculating the intersections with the tetrahedral faces. The method allows us to incorporate topological information from the cells, e.g. critical points. The calculations are based on barycentric coordinates, since this simplifies the theory and the algorithm. The stream surfaces are ruled surfaces inside each cell, and their construction starts with line segments on the faces. Our method supports the analysis of velocity fields resulting from computational fluid dynamics (CFD) simulations.