Fast animation of Amorphous and Gaseous Phenomena

Scott King,
Roger Crawfis,
Wayland Reid.
 

Abstract

We present a technique to animate amorphous materials such as fire, smoke and dust in real-time on graphics hardware with dedicated texture memory. Our method uses a coarse voxel grid to model object dynamics, and texture cycling to create local and global dynamics. Detail is added by encoding high-frequency components, which are normally spread uniformly throughout the volume, into the volume integration. The individual voxels are rendered using a splatting approach with a table of anisotropic footprint functions. Our method produces a truly three-dimensional volume effect that can interact with the rest of the environment.

Using different spectral scales for the volume's appearance allows for motion at three distinct and disjoint scales. Local dynamics are achieved by phase-shifting through a set of textures within a voxel. Global dynamics, such as eddies, are propagated through the volume using inter-voxel dynamics. Object dynamics are achieved using procedural or keyframe animation techniques on the low-resolution voxel grid. We also develop an automated technique for texture selection by sampling a single large image having various frequency components.

Keywords: Fire, smoke, clouds, gaseous phenomena, volume rendering, atmosphere, splatting, textured splats, animation.

Please visit our permanent web site http://www.cse.ohio-state.edu/graphics/research/fire/

Figures.


Figure 1a Figure 1a. Modeling fire with a 7x20x5 voxel grid using traditional splatting.

figure 1b Figure 1b. Modling fire with a 7x20x5 voxel grid using our method of incorporating detail into the splats.

figure 2 Figure 2. A texture is weighted with the splat footprint function to produce a textured splat containing embedded detail.

figure 3 Figure 3. Several stills from an animation of a cow moving through fire.

figure 4 Figure 4. A herd kicking up a cloud of dust.

figure 5 Figure 5. A steaming Utah teapot.

figure 6 Figure 6. A bonfire cut from a photograph of real fire.

figure 7 Figure 7. Resulting set of textures generated by randomly sampling figure 6.

figure 8 Figure 8. The resulting fire image using the textures from figure 7.

figure 9 Figure 9. Image from real-time animation of smoke emanating from a locomotive.

figure 10 Figure 10. Artistic application. A low-resolution volume textured with human faces, gives the effects of ghosts.

figure 11 Figure 11. The volume effect on the left was created by randomly sampling the texture on the right.

This paper was presented at Volume Graphics '99 .

Created Jan 30, 1999 by Scott King