Search papers, labs, and topics across Lattice.
GST-VLA introduces Gaussian Spatial Tokens (GST) to encode visual observations in VLA models as anisotropic 3D Gaussian primitives, enabling the model to capture geometric structure and surface orientation from depth and semantic patch features. It also incorporates 3D Depth-Aware Chain-of-Thought (DA-CoT) reasoning, supervising structured intermediate spatial thoughts for improved spatial understanding. GST-VLA achieves state-of-the-art performance on LIBERO (96.4%) and SimplerEnv (80.2%), demonstrating the effectiveness of the proposed geometric representation and reasoning approach.
By representing visual inputs as 3D Gaussian primitives, GST-VLA unlocks a new level of geometric understanding for vision-language-action models, leading to substantial performance gains in robotic manipulation tasks.
VLA models encode visual observations as 2D patch tokens with no intrinsic geometric structure. We introduce GST-VLA with two contributions. First, the Gaussian Spatial Tokenizer (GST) converts frozen dense depth and frozen semantic patch features into $N_g{=}128$ anisotropic 3D Gaussian primitives, each parameterized by a metric residual mean $\mu \in \mathbb{R}^3$, log-scale covariance $\log \sigma \in \mathbb{R}^3$, and learned opacity $\alpha \in (0,1)$. The covariance eigenstructure encodes local surface orientation, and opacity provides per-primitive geometric confidence, both inaccessible from scalar depth. Spatial attention pooling with learned queries concentrates the fixed token budget on geometrically salient regions rather than distributing uniformly. Second, 3D Depth-Aware Chain-of-Thought (DA-CoT) reasoning supervises four structured intermediate spatial thoughts, covering 3D object grounding, grasp affordance contact geometry, pairwise metric distances, and coarse SE(3) waypoints, as explicit generation targets in the training loss. A cross-attention sublayer at every VLM transformer block provides direct access to the raw 256-primitive Gaussian field during DA-CoT generation. A 300M-parameter flow-matching action expert with mixture-of-experts feedforward sublayers decodes 7-DoF delta action chunks via conditional ODE integration, conditioned on both VLM hidden states and DA-CoT outputs through dual cross-attention. Trained with composite $\mathcal{L}_\mathrm{flow} + \mathcal{L}_\mathrm{CoT} + \mathcal{L}_\mathrm{depth}$ across three progressive stages, GST-VLA achieves 96.4% on LIBERO (+2.0%), and 80.2% on SimplerEnv (+5.4%). Ablations isolate the contribution of each GST component, each DA-CoT thought, and each training stage, confirming independent and synergistic gains concentrated on precision demanding tasks.
