“Surface Constraint Wing Fold System on The Wild Robot” by Inagaki, Boucher, Jensen and Amos
Conference:
Type(s):
Title:
- Surface Constraint Wing Fold System on The Wild Robot
Session/Category Title:
- Lots 'o' Limbs
Presenter(s)/Author(s):
Moderator(s):
Abstract:
Animating realistic bird wing folds in computer animation is a challenging task. Even after achieving a beautifully folded pose, keeping the wings firmly on the torso during actions and performances often requires labor-intensive counter animations. In this talk, we introduce our innovative surface constraint wing fold system developed for The Wild Robot, which significantly reduces the need for such counter animation. Building upon DreamWorks Animation’s previous work, our approach centers on constraining wings and feather plane joints to a dedicated “wing fold surface” that is deformed solely by full-body joints, deliberately excluding the wing joints. This is achieved by replacing the wing joints’ skin weights with those of a spine joint, the parent of the wing hierarchy, thereby eliminating problematic dependency loops. We further refined the system by adopting a hybrid blending strategy: wing joints are blended in world space to prevent unintended swinging, while feather plane joints are blended in local space to preserve their attachment. Moreover, our design incorporates intuitive blend controls that allow animators to independently adjust the constraint tightness for primary, secondary, and scapular feathers, providing enhanced artistic control. Additional improvements include the introduction of a no-twist spine joint strand and a collision deformer, which together prevent interpenetration with the torso and accommodate both realistic and exaggerated cartoon-style animations. Deployed across multiple sequences in The Wild Robot, our system has successfully supported both hero characters and background geese, streamlining production across 17 shots, including crowd scenes, while maintaining high artistic quality.
