S4D: Streaming 4D Real-World Reconstruction with Gaussians and 3D Control Points

Recently, the dynamic scene reconstruction using Gaussians has garnered increased interest. Mainstream approaches typically employ a global deformation field to warp a 3D scene in the canonical space. However, the inherently low-frequency nature of implicit neural fields often leads to ineffective representations of complex motions. Moreover, their structural rigidity can hinder adaptation to scenes with varying resolutions and durations. To overcome these challenges, we introduce a novel approach utilizing discrete 3D control points. This method models local rays physically and establishes a motion-decoupling coordinate system, which effectively merges traditional graphics with learnable pipelines for a robust and efficient local 6-degrees-of-freedom (6-DoF) motion representation. Additionally, we have developed a generalized framework that incorporates our control points with Gaussians. Starting from an initial 3D reconstruction, our workflow decomposes the streaming 4D real-world reconstruction into four independent submodules: 3D segmentation, 3D control points generation, object-wise motion manipulation, and residual compensation. Our experiments demonstrate that this method outperforms existing state-of-the-art 4D Gaussian Splatting techniques on both the Neu3DV and CMU-Panoptic datasets. Our approach also significantly accelerates training, with the optimization of our 3D control points achievable within just 2 seconds per frame on a single NVIDIA 4070 GPU.

Atlas3D: Physically Constrained Self-Supporting Text-to-3D for Simulation and Fabrication

Existing diffusion-based text-to-3D generation methods primarily focus on producing visually realistic shapes and appearances, often neglecting the physical constraints necessary for downstream tasks. Generated models frequently fail to maintain balance when placed in physics-based simulations or 3D printed. This balance is crucial for satisfying user design intentions in interactive gaming, embodied AI, and robotics, where stable models are needed for reliable interaction. Additionally, stable models ensure that 3D-printed objects, such as figurines for home decoration, can stand on their own without requiring additional supports. To fill this gap, we introduce Atlas3D, an automatic and easy-to-implement method that enhances existing Score Distillation Sampling (SDS)-based text-to-3D tools. Atlas3D ensures the generation of self-supporting 3D models that adhere to physical laws of stability under gravity, contact, and friction. Our approach combines a novel differentiable simulation-based loss function with physically inspired regularization, serving as either a refinement or a post-processing module for existing frameworks. We verify Atlas3D's efficacy through extensive generation tasks and validate the resulting 3D models in both simulated and real-world environments.

Bayesian Neural Networks Tend to Ignore Complex and Sensitive Concepts

In this paper, we focus on mean-field variational Bayesian Neural Networks (BNNs) and explore the representation capacity of such BNNs by investigating which types of concepts are less likely to be encoded by the BNN. It has been observed and studied that a relatively small set of interactive concepts usually emerge in the knowledge representation of a sufficiently-trained neural network, and such concepts can faithfully explain the network output. Based on this, our study proves that compared to standard deep neural networks (DNNs), it is less likely for BNNs to encode complex concepts. Experiments verify our theoretical proofs. Note that the tendency to encode less complex concepts does not necessarily imply weak representation power, considering that complex concepts exhibit low generalization power and high adversarial vulnerability.

Midas: A Multi-Joint Robotics Simulator with Intersection-Free Frictional Contact

We introduce Midas, a robotics simulation framework based on the Incremental Potential Contact (IPC) model. Our simulator guarantees intersection-free, stable, and accurate resolution of frictional contact. We demonstrate the efficacy of our framework with experimental validations on high-precision tasks and through comparisons with Bullet physics. A reinforcement learning pipeline using Midas is also developed and tested to perform intersection-free peg-in-hole tasks.