Figure 1: This sequence of water sloshing back and forth in an invisible tank demonstrates our cartoon rendering style for liquid animations. The sequence begins when the fluid is released from a cuboid shape, sloshes against the opposite wall, back against the first wall, and eventually settles on the ground. In this paper we present a visually compelling and informative cartoon rendering style for liquid animations. Our style is inspired by animations such as Futurama, 1 The Little Mermaid, 2 and Bambi 2. We take as input a liquid surface obtained from a three-dimensional physically based liquid simulation system and output animations that evoke a cartoon style and convey liquid movement. Our method is based on four cues that emphasize properties of the liquid’s shape and motion. We use bold outlines to emphasize depth discontinuities, patches of constant color to highlight near-silhouettes and areas of thinness, and, optionally place temporally coherent oriented textures on the liquid surface to help convey motion. CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism—Animation;

We present a novel approach to create stylised animations of gaseous phenomena. Existing computer-assisted systems employ computational physics-based approaches which generate 3D effects. Unfortunately, these effects usually don't look like traditional animation, nor can the user freely design the behaviour of the animation.

Figure 1: Our mid-level fluid control system allows artists to specify local smoke behavior by providing density motifs (left). The resulting fluid can be integrated with 2D animations (center left). In this case, we have recolored the smoke to match the wand colors. Other effects our system can generate (center right) include global textures such as clouds reminiscent of those found in Katsushika Hokusai’s prints (right). In this paper we introduce the notion that artists should be able to control fluid simulations by providing examples of expected local fluid behavior (for instance, an artist might specify that magical smoke often forms star shapes). As our idea fits between high-level, global pose control and low-level parameter adjustment, we deem it mid-level control. We make our notion concrete by demonstrating two mid-level controllers providing stylized smoke effects for two-dimensional animations. With these two controllers, we allow the artist to specify both density patterns, or particle motifs, which should emerge frequently within the fluid and global texture motifs to which the fluid should conform. Each controller is responsible for constructing a stylized version of the current fluid state, which we feed-back into a global pose control method. This feedback mechanism allows the smoke to retain fluid-like behavior, while also attaining a stylized appearance suitable to integration with 2D animations. We integrate these mid-level controls with an interactive animation system, in which the user can control and keyframe all animation parameters using an interactive timeline view.

We describe a rendering system that converts a 3D meshed model into the stylized 2D filled-region vector-art commonly found in clip-art libraries. To properly define filled regions, we analyze and combine accurate but jagged face-normal contours with smooth but inaccurate interpolated vertex normal contours, and construct a new smooth shadow contour that properly surrounds the actual jagged shadow contour. We decompose region definition into geometric and topological components, using machine precision for geometry processing and raster-precision to accelerate topological queries. We extend programmable stylization to simplify, smooth and stylize filled regions. The result renders 10K-face meshes into custom clip-art in seconds. 1.