GRAIL: Generating Humanoid Loco-Manipulation from 3D Assets and Video Priors

Tianyi Xie1,2,*   Haotian Zhang1,*   Jinhyung Park1,*   Zi Wang1,*   Bowen Wen1   Jiefeng Li1   Xueting Li1   Qingwei Ben1  
Haoyang Weng1   Yufei Ye1   David Minor1   Tingwu Wang1   Chenfanfu Jiang2   Sanja Fidler1  
Jan Kautz1   Linxi "Jim" Fan1   Yuke Zhu1   Zhengyi Luo1,†   Umar Iqbal1,†   Ye Yuan1,†  
1 NVIDIA     2 UCLA
* Co-First Authors     Project Leads
NVIDIA UCLA

Abstract

Scaling humanoid loco-manipulation requires robot-compatible demonstrations across diverse objects, whole-body motions, and scene geometries, but teleoperation and motion capture are difficult to scale because each collection depends on physical setups, instrumented actors, and robot operation. We present GRAIL, a digital generation pipeline that remains fully virtual until deployment: it composes 3D assets, simulator-ready scenes, and priors from video foundation models to synthesize interactions without rebuilding physical environments or teleoperating the robot.

Rather than reconstructing unconstrained in-the-wild videos, GRAIL starts from fully specified 3D configurations in which object geometry, camera parameters, metric scale, environment depth, and a robot-proportioned character are known before video generation and reused during reconstruction. We retarget the recovered motions to a humanoid robot and train complementary task-general trackers for manipulation and locomotion. GRAIL produces over 20,000 sequences spanning pick-up, whole-body manipulation, sitting, and terrain traversal, and transfers to real Unitree G1 deployment for object pick-up and stair-climbing.

Motion Gallery

GRAIL covers both object-centric interactions and scene-centric whole-body motion. The gallery below shows object manipulation and scene-aware locomotion as two complementary capability blocks.

Sim-to-Real Deployment

We deploy policies trained with GRAIL-generated data on a real Unitree G1, covering egocentric RGB-based pick-up and stair-climbing as well as GR00T fine-tuning with a small teleoperation data mixture.

Rendered Egocentric Views for Policy Training

GRAIL renders egocentric RGB videos from generated grasping demonstrations, providing visual-policy training data before transferring the policy to real-world deployment.

Egocentric Visual Policy Deployment

We train egocentric RGB policies on GRAIL-generated data and deploy them on a Unitree G1 for real-world object pick-up and stair-climbing.

Real-world pick-up

Real-world stair-climbing

GR00T Fine-tuning

We also evaluate GRAIL as data for GR00T fine-tuning. Early co-training experiments use a 95% GRAIL and 5% teleoperation data mixture, improving grasping success over teleoperation-only training and reducing the chance that the policy gets stuck before reaching the target.

Method

Given a 3D object asset, GRAIL produces humanoid loco-manipulation demonstrations comprising humanoid motion, object motion, and robot actions. The pipeline proceeds in three stages: it assembles a fully specified 3D configuration with a character prefitted to the target robot and synthesizes a reference human-object interaction video with a video foundation model; it reconstructs coherent metric 4D HOI trajectories using the known scene context; and it retargets the recovered motions to the Unitree G1 to train task-general tracking policies, followed by egocentric RGB policies for sim-to-real deployment.

Asset-conditioned 4D human-object interaction generation pipeline
Asset-conditioned 4D HOI generation. GRAIL renders a fully specified 3D scene with known camera parameters, conditions a video foundation model on the rendered frame to synthesize an interaction video, and reconstructs metric 4D human-object motion through pose estimation, object tracking, and interaction-aware optimization.
Task-general humanoid tracking and policy adaptation pipeline
Task-general tracking. Retargeted 4D HOI trajectories are converted into robot-action data by adapting complementary parts of a pretrained whole-body controller, enabling object-aware manipulation policies and scene-aware locomotion policies for terrain traversal and sitting.