Maya splash effect
1
Directable Simulation of Stylized Water Splash Effects in 3D Space John David Thornton, Effects Animator/Technical Director, Blue Sky Studios 1. Description This sketch identifies stylized visual qualities found in traditionally animated 2D water splash effects and establishes a method for capturing their essence, posing and animating them in 3D space. This method was employed for many of the splash effects in Ice Age: The Meltdown . 2. Inspiration In traditional 2D feature animation, water splash effects exhibit a strong artistic style, of which the following qualities are characteristic: A dynamic silhouette A strong leading edge Discernible interior “columns” Larger-than-life droplets anticipating the leading edge Holes torn in the “sheet” 3-stage progression of a traditional 2D splash 3. Challenge Water splash effects in CG animated films often utilize computational fluid dynamics (CFD) to produce physically-based simulations. This approach can yield favorable results, but is limited in its ability to incorporate stylization and other special animation considerations beyond realism or surrealism. Furthermore, it poses challenges in establishing control over the shapes of the splashes, especially when they react to an often- cheated, physically incorrect 3D world. For example, using CFD could make a cumbersome task of opening a small area within a large splash so that the expression on the face of a character could be staged. The tight production schedule for Ice Age: The Meltdown and its mandate for a large volume of water splash effects necessitated a solution which satisfied the following criteria: Establish high-quality splash effects which complement the established visual style of Ice Age . Direct control of specific elements of the splashes relative to the performance of the characters. Produce a large volume of these effects rapidly. Make the technique simple and easily implemented by people with varying disciplines outside of effects, such as character animators. 4. Execution – Construction An extremely light, modular rig was created which enables these stylized splashes to be posed and animated in 3D space. The rig is composed of, at its lowest level, a series of nodes which travel perpetually in world space along ballistic arcs, driven by expressions. Each node is a point of “resolution” which describes the shape of the splash. The velocity, world position and time value of each node is determined by user input. These nodes are grouped into parent columns, each with a user- defined per-column offset or multiplier of the above values. Finally, the columns are grouped into a global parent which has yet another series of offsets and multipliers. The cumulative values of each low-level node, with its inherited offsets and multipliers, are what describe the timing and physical profile of the splash. Particle emitters are constrained to these nodes, and the particles inherit their velocities. Several particle systems are utilized, each with its own unique objective in conveying the style, and can be modified to adapt to various artistic looks. From left to right: one rig, twenty columns, forty points. The rig is a modular array of similar nodes. Time, space, direction and force are established per-rig, then varied per-column and per-point. 5. Execution - Workflow The workflow is similar to that of traditional animation, although little keyframing is required. The rig is visually interactive. Dynamics are hidden while splashes are “roughed out”. The user positions the rig and establishes global timing, force and direction. Offsets of these values are then specified for each column, to time and “sculpt” the leading edge of the splash. Finally, individual node values within the columns are varied. Each successive stage of the workflow “carves” further localized detail into the physical profile. 4-stage progression of a splash using the rig described The rig is capable of creating many unique splash effects: Rain plinks, medium “kerplunks” and huge mist splashes Wakes (“rooster-tails”) Up/down inclines (e.g., displacement down a water slide) Cast from a moving source (e.g., sloshing from a bucket) Cast with force from above (e.g., waterfall) Constant sources (e.g., faucets, geysers, hoses) Viscous fluids (e.g., mud) and debris, such as rocks and ice Moreover, it can easily be built around static and animating elements in a shot. Layered complexity is achieved by cloning rigs, or groups of rigs, and varying settings on the clones. Entire simulations can be moved, scaled and rotated in world space. Splashes of one type can be transformed into another simply by rearranging the columns within. For example, a linear “rooster- tail” can be transformed into a circular “kerplunk”, while preserving individual variation within the columns. Splash libraries can be compiled from each variation. A mosaic of splash types. Top: milk droplet, wake and raindrop. Bottom: large-scale splashes from Ice Age: The Meltdown .
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Autodesk Maya splash effect
Transcript of Maya splash effect
Directable Simulation of Stylized Water Splash Effects in 3D SpaceJohn David Thornton, Effects Animator/Technical Director, Blue Sky Studios
1. DescriptionThis sketch identifies stylized visual qualities found in
traditionally animated 2D water splash effects and establishes a method for capturing their essence, posing and animating them in 3D space. This method was employed for many of the splash effects in Ice Age: The Meltdown.
2. InspirationIn traditional 2D feature animation, water splash effects exhibit
a strong artistic style, of which the following qualities are characteristic:
A dynamic silhouetteA strong leading edgeDiscernible interior “columns”Larger-than-life droplets anticipating the leading edgeHoles torn in the “sheet”
3-stage progression of a traditional 2D splash
3. ChallengeWater splash effects in CG animated films often utilize
computational fluid dynamics (CFD) to produce physically-based simulations. This approach can yield favorable results, but is limited in its ability to incorporate stylization and other special animation considerations beyond realism or surrealism.
Furthermore, it poses challenges in establishing control over the shapes of the splashes, especially when they react to an often-cheated, physically incorrect 3D world. For example, using CFD could make a cumbersome task of opening a small area within a large splash so that the expression on the face of a character could be staged.
The tight production schedule for Ice Age: The Meltdown and its mandate for a large volume of water splash effects necessitated a solution which satisfied the following criteria:
Establish high-quality splash effects which complement the established visual style of Ice Age.Direct control of specific elements of the splashes relative to the performance of the characters.Produce a large volume of these effects rapidly.Make the technique simple and easily implemented by people with varying disciplines outside of effects, such as character animators.
4. Execution – ConstructionAn extremely light, modular rig was created which enables these
stylized splashes to be posed and animated in 3D space. The rig is composed of, at its lowest level, a series of nodes which travel perpetually in world space along ballistic arcs, driven by expressions. Each node is a point of “resolution” which describes the shape of the splash. The velocity, world position and time value of each node is determined by user input.
These nodes are grouped into parent columns, each with a user-defined per-column offset or multiplier of the above values. Finally, the columns are grouped into a global parent which has yet another series of offsets and multipliers. The cumulative values of each low-level node, with its inherited offsets and multipliers, are
what describe the timing and physical profile of the splash. Particle emitters are constrained to these nodes, and the particles inherit their velocities. Several particle systems are utilized, each with its own unique objective in conveying the style, and can be modified to adapt to various artistic looks.
From left to right: one rig, twenty columns, forty points. The rig is a modular array of similar nodes. Time, space, direction and force
are established per-rig, then varied per-column and per-point.
5. Execution - WorkflowThe workflow is similar to that of traditional animation,
although little keyframing is required. The rig is visually interactive. Dynamics are hidden while splashes are “roughed out”. The user positions the rig and establishes global timing, force and direction. Offsets of these values are then specified for each column, to time and “sculpt” the leading edge of the splash. Finally, individual node values within the columns are varied. Each successive stage of the workflow “carves” further localized detail into the physical profile.
4-stage progression of a splash using the rig described
The rig is capable of creating many unique splash effects:Rain plinks, medium “kerplunks” and huge mist splashesWakes (“rooster-tails”)Up/down inclines (e.g., displacement down a water slide)Cast from a moving source (e.g., sloshing from a bucket)Cast with force from above (e.g., waterfall)Constant sources (e.g., faucets, geysers, hoses)Viscous fluids (e.g., mud) and debris, such as rocks and ice
Moreover, it can easily be built around static and animating elements in a shot. Layered complexity is achieved by cloning rigs, or groups of rigs, and varying settings on the clones. Entire simulations can be moved, scaled and rotated in world space. Splashes of one type can be transformed into another simply by rearranging the columns within. For example, a linear “rooster-tail” can be transformed into a circular “kerplunk”, while preserving individual variation within the columns. Splash libraries can be compiled from each variation.
A mosaic of splash types. Top: milk droplet, wake and raindrop.Bottom: large-scale splashes from Ice Age: The Meltdown.
