3Eth Ai Center
https://cvlab-kaist.github.io/Geometric-Action-Model
Geometric Foundation Model
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Figure 1: GAM repurposes geometric foundation models into fast and robust robot policies. (a) GAM jointly predicts future 3D geometry and action chunks within a shared geometric backbone. (b) By leveraging explicit 3D geometric priors, GAM improves robustness and real-world perfor- mance while reducing latency and model size compared to existing baselines.
Abstract: Generalist robot policies must follow user instructions while reasoning about how objects, cameras, and robot actions interact in the 3D physical world. Recent vision-language-action models (VLAs) and video world-action models (WAMs) inherit strong semantic or temporal priors from large-scale foundation models, but they still operate primarily on 2D image frames or 2D-derived la- tent spaces, leaving implicit the 3D geometry required for contact-rich manipula- tion. We propose the Geometric Action Model (GAM), a language-conditioned manipulation policy that directly repurposes a pretrained geometric foundation model (GFM) as a shared substrate for perception, temporal prediction, and ac- tion decoding. GAM splits the GFM at an intermediate layer: the shallow layers serve as an observation encoder, and a causal future predictor inserted at the split layer forecasts future latent tokens conditioned on language, proprioception, and action history. The predicted future tokens are then routed through the remain- ing GFM blocks for feature propagation and decoding, allowing a single back- bone to produce both future geometry and actions. This design equips the GFM with language-conditioned temporal world modeling through minimal architec- tural modification while preserving its rich geometric priors. Across a broad suite of simulation and real-robot manipulation benchmarks, GAM is more accurate, more robust, faster, and lighter than current foundation-model-scale baselines.
∗Equal contribution. †Corresponding author.
Introduction
A long-standing goal in robotics is to build generalist manipulation policies that can follow natural- language instructions and manipulate arbitrary objects across diverse scenes [1, 2, 3, 4]. To achieve this, a general manipulation model must not only recognize objects and parse instructions, but also reason about how the physical world will evolve under its own actions. This requires a unified understanding of language, visual appearance, scene geometry, robot state, and physical dynamics.
Recent progress has therefore increasingly relied on large-scale foundation models as pretrained substrates for robot policies. Vision-language-action models (VLAs) build on vision-language mod- els whose representations are aligned with natural language, and learn to map visual and linguistic tokens to robot actions [5, 1, 2, 4, 6, 7]. Video world-action models (WAMs) instead leverage pre- trained video generation models, using their world prediction priors to jointly model future frames and actions [3, 8]. While these approaches have shown impressive language-conditioned manipu- lation ability, they are fundamentally in 2D: 3D cues such as depth, scale, and occlusion are left implicit in monocular cues that the action decoder must disentangle on its own, leading to lim- ited generalization across environment changes, especially in robot initial state and camera view- point [9, 10].
To overcome this limitation, recent work incorporates 3D geometric information into robot poli- cies. One line learns policies directly on explicit 3D observations such as raw point clouds [11, 12], demonstrating the value of geometry for generalization but typically requiring task-specific encoders trained from scratch. With the emergence of Geometric Foundation Models (GFMs) [13, 14, 15], some works transfer pretrained geometric priors into VLA policies, either distilling selected GFM features into the VLA backbone through representation alignment [16, 17, 18] or attaching a lightweight action head on top of a GFM’s final features [19, 20]. These improve spatial aware- ness, but use the GFM only as a static feature extractor: its multi-layer geometric structure is never repurposed as the policy’s own temporal and action-generating substrate.
In this work, we propose Geometric Action Model (GAM), which directly repurposes a GFM as a manipulation policy by using it as a shared medium for perception, future-state prediction, and action decoding. We show that by jointly predicting future action and geometry, geometric world dynamics can be inherently incorporated into robot policies.
Specifically, we split the pretrained GFM at an intermediate layer: the shallow layers serve as an observation encoder, while the remaining layers serve as a decoder block. Given the current visual observation, the observation encoder extracts spatially meaningful scene representations. To model how the world evolves over time, we insert a causal transformer at the intermediate layer that predicts future feature representations. This predictor is conditioned on task language, proprioception, and action history by introducing them as additional tokens at each timestep. The predicted future-state tokens are then processed by the remaining GFM decoder together with an action token, allowing the backbone to produce both future geometry and robot actions. An intuitive comparison between existing paradigms and our proposed framework is illustrated in Figure 2.
Across diverse simulation [21, 9, 22] and real-world benchmarks, GAM matches or exceeds the success rate of current foundation-model-scale baselines such as VLAs and WAMs while using substantially fewer trainable parameters and substantially faster inference (55× faster), and shows improved generalization to unseen scenarios. GAM especially achieves outstanding performance in camera perturbation settings (↑9.7%p), which requires geometric understanding priors.
Our Contributions Are As Follows:
• We introduce Geometric Action Model (GAM), a manipulation policy that combines tem- poral world modeling, latent feature-space prediction, and a geometric foundation-model substrate in a single shared-backbone architecture.
• We show that action and geometry can be predicted in a shared token space: a single autoregressive sequence and a single backbone forward pass produce both action tokens and future-scene tokens, decoded by a lightweight action regression head and a depth head.
Action Head
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Figure 2: (a) Video WAMs [3, 8, 23] operate in 2D pixel space, predicting future latents and actions via video diffusion. (b) Geometry-aware VLAs [17, 18] predict actions using a VLA with passive feature distillation from an external GFM. (c) GAM (ours) unifies perception, geometry prediction, and action decoding by inserting a geometric world model inside a single GFM.
• We demonstrate that across diverse simulation and real-world manipulation benchmarks, GAM is simultaneously more accurate, more robust, faster, and lighter than current foundation-model-scale alternatives.
Related Work
Vision-Language-Action Models. Vision-language-action models (VLAs) adapt a pretrained vision-language model (VLM) into a robot policy. Early works [5, 1] autoregressively decode dis- crete action tokens from a finetuned VLM. This paradigm is extended through parallel decoding , flow-matching action experts [4, 6, 24], diffusion-based action heads , frequency-space action tokenizations , and compact open-source VLMs [26, 27]. This line of work extends large general- ist foundation models for humanoid and embodied control [28, 29, 30, 31], to spatial-representation variants , and to refinements in training and post-training [33, 34, 35]. While these VLAs lever- age strong open-vocabulary recognition to produce policies, they rely solely on 2D image priors and therefore lack 3D understanding. To address this, recent works [17, 18, 36] attempt to align intermediate VLA features with geometric foundation model. However, they do not fully exploit the geometric understanding of geometric foundation model backbone.
World Action Models for Robot Manipulation. World action models are trained to predict future states in order to learn a policy. One branch builds on large pretrained video generation models , fine-tuning them to jointly predict future frames and actions [3, 8, 23], arguing that the benefit of such co-training stems primarily from training-time supervision rather than test-time future imag- ination [23, 7]. A second branch keeps the visual backbone frozen and trains a separate temporal predictor in its feature space for planning via model-predictive control [38, 39], with related work using implicit future-latent alignment as an auxiliary training signal . However, these video backbones encode only 2D image-space priors, which do not explicitly resolve depth, scale, or oc- clusion. GAM instead predicts in the latent space of a geometric foundation model that encodes rich 3D priors, while inheriting from both branches the paradigm of using future prediction as a training signal.
Geometric Foundation Models for Manipulation. Geometric foundation models (GFMs) [14, 13, 41, 42] infer dense 3D structures from multi-view images and have recently served as perceptual substrates for robot policies. Early approaches integrate GFMs with VLAs as frozen feature ex- tractors via representation alignment [17, 18], direct encoder replacement [36, 19], or point-cloud fusion . Moving beyond static extraction, recent concurrent works adopt GFMs for predictive control: Song et al. utilizes the GFM to jointly predict actions and current-frame 3D properties, while Xu et al. employs the GFM with a diffusion policy to co-denoise future action chunks and
Causal Transformer Layer
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Figure 3: Main architecture of GAM. 3D latents. GAM departs from these paradigms in two ways: (1) action and future-scene predictions are jointly modeled within a single autoregressive token sequence rather than separated heads or diffusion processes, and (2) the GFM’s deep blocks are explicitly repurposed to decode predicted future tokens rather than merely processing observed ones.
Preliminaries: Geometric Foundation Models
A geometric foundation model (GFM) such as VGGT or DA3 is a feed-forward transformer that maps one or more RGB images to dense 3D geometry. Given a sequence of V views I =
{Iv}V
v=1 with Iv ∈R3×h×w, a GFM produces per-pixel depth Dv ∈Rh×w or 3D point maps Pv ∈R3×h×w in a shared world frame, and per-view camera intrinsics and extrinsics (Kv, ξv) ∈ R3×3 × SE(3) via auxiliary heads. Specifically, each view Iv is partitioned into P non-overlapping patches of size p × p and projected by a patch embedding into a per-view token sequence:
V}P
j=1 are patch tokens, and d is the hidden dimension. The full input sequence concatenated across views is Z(0) = [z(0)
1 , . . . , Z(0)
V ] ∈RV (1+P )×d. These tokens are processed by a stack of M transformer blocks {f (m)}M
Attention Modes. Frame-Wise Attention F (M)
frame operates within each view tokens independently, at- tending over the (1 + P) tokens of a single image. Global attention f (m)
Global Operates Jointly Over All
V (1 + P) tokens, fusing information across viewpoints. The hidden state at the m-th transformer
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global}.
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After the transformer forward pass, dense geometry is decoded from multiple intermediate hidden states Z(m∗), where m∗is one of the selected layers in S = {m1, m2, m3, m4}. The extracted multi-layer hidden states are then fed into the DPT head to estimate per-pixel geometry.
Gam: Geometric Action Model
Problem Formulation. We consider language-conditioned robot manipulation. At each timestep t, the robot receives a multi-view RGB observation ot = {Iv,t}V
V=1 From V Fixed Cameras, A Pro-
prioceptive state st ∈Rds describing the robot’s joint configuration and end-effector pose, and a natural-language task instruction ℓthat is held constant throughout an episode. The policy πθ must produce an action chunk ˆat ∈RC×da of length C, encoding the next C delta-pose or joint com- mands to be executed open-loop before the next observation is acquired. We learn a policy: