Abstract Reducing the triangle count in complex 3D models is a basic geometry preprocessing step in graphics pipelines such as efficient rendering and interactive editing. However, most existing mesh simplification methods exhibit a few issues. Firstly, they often lead to self‐intersections during decimation, a major issue for applications such as 3D printing and soft‐body simulation. Second, to perform simplification on a mesh in the wild, one would first need to perform re‐meshing, which often suffers from surface shifts and losses of sharp features. Finally, existing re‐meshing and simplification methods can take minutes when processing large‐scale meshes, limiting their applications in practice. To address the challenges, we introduce a novel GPU‐based mesh optimization approach containing three key components: (1) a parallel re‐meshing algorithm to turn meshes in the wild into watertight, manifold, and intersection‐free ones, and reduce the prevalence of poorly shaped triangles; (2) a robust parallel simplification algorithm with intersection‐free guarantees; (3) an optimization‐based safe projection algorithm to realign the simplified mesh with the input, eliminating the surface shift introduced by re‐meshing and recovering the original sharp features. The algorithm demonstrates remarkable efficiency, simplifying a 2‐million‐face mesh to 20k triangles in 3 seconds on RTX4090. We evaluated the approach on the Thingi10K dataset and showcased its exceptional performance in geometry preservation and speed. https://seonghunn.github.io/pamo/

In physics-based simulation of rigid or nearly rigid objects, collisions often become the primary performance bottleneck, particularly when enforcing intersection-free constraints. Previous simulation frameworks rely on primitive-level CCD algorithms. Due to the large number of colliding surface primitives to process, those methods are computationally intensive and heavily dependent on advanced parallel computing resources such as GPUs, which are often inaccessible due to competing tasks or capped threading capacity in applications like policy training for robotics. To address these limitations, we propose a sequential CCD algorithm for convex shapes undergoing constant affine motion. This approach uses the conservative advancement method to iteratively refine a lower-bound estimate of the TOI, exploiting the linearity of affine motion and the efficiency of convex shape distance computation. Our CCD algorithm integrates seamlessly into the ABD framework, achieving a 10-fold speed-up over primitive-level CCD. Its high single-threaded efficiency further enables significant throughput improvements via scene-level parallelism, making it well-suited for resource-constrained environments.

Visuotactile sensors can provide rich contact information, having great potential in contact-rich manipulation tasks with reinforcement learning (RL) policies. Sim2Real technique tackles the challenge of RL's reliance on a large amount of interaction data. However, most Sim2Real methods for manipulation tasks with visuotactile sensors rely on rigid-body physics simulation, which fails to simulate the real elastic deformation precisely. Moreover, these methods do not exploit the characteristic of tactile signals for designing the network architecture. In this paper, we build a general-purpose Sim2Real protocol for manipulation policy learning with marker-based visuotactile sensors. To improve the simulation fidelity, we employ an FEM-based physics simulator that can simulate the sensor deformation accurately and stably for arbitrary geometries. We further propose a novel tactile feature extraction network that directly processes the set of pixel coordinates of tactile sensor markers and a self-supervised pre-training strategy to improve the efficiency and generalizability of RL policies. We conduct extensive Sim2Real experiments on the peg-in-hole task to validate the effectiveness of our method. And we further show its generalizability on additional tasks including plug adjustment and lock opening. The protocol, including the simulator and the policy learning framework, will be open-sourced for community usage.