Real-time generation of stylized motion-blur (smears) for skinned-meshes on the GPU

Sammanfattning

Recent trends in 3D graphics have embraced stylization approaches inspired by traditional 2D animation. One such technique, known as “smears”, is a form of stylized motion blur that exaggerates motion by stretching objects along their motion trajectory. Current methods of applying this technique within real-time interactive environments are either artist-driven, reliant on bespoke labor-intensive solutions, or too slow for real-time deployment. This thesis investigates the feasibility, visual consistency, and usability of automatically generating stylized smear effects for skinned 3D meshes within real-time interactive systems through adapting the 2024 offline SMEAR method. A GPU-based multi-pass compute shader adaptation of SMEAR was implemented in the 3D game engine Unity. Performance was evaluated by measuring per-frame computation times across varying vertex counts (1,000 to 1,024,000) and skeletal complexities (1 to 512 bones). Usability and visual consistency were further assessed through qualitative semi-structured expert interviews with animators and technical animators who evaluated the effect in both interactive and non-interactive settings. This thesis demonstrates that the SMEAR method can operate within real-time budgets (under 1ms overhead) across all test cases, performing around 1.3-3.2× the time of GPU linear-blend skinning on a NVIDIA GeForce RTX 4070, with vertex count emerging as the dominant cost factor. The key contributions of this work include: (1) proposing and validating the feasibility of a parallel GPU SMEAR implementation in a real-time interactive context, (2) highlighting the importance of vertex and memory optimization for future scalability, (3) introducing motion-aligned smears (MA-SMEAR) as a novel stylization strategy, and (4) identifying the need for improved art-directability and visual consistency for practical use within production settings. This research advances the integration of stylized animation techniques into real-time interactive 3D applications, bridging the gap between artistic expression and technical execution.