Glossary
What Is Im2Flow2Act?
Last reviewed: November 2026
Short answer
Im2Flow2Act is a published framework (arXiv 2407.15208, Flow as the Cross-Domain Manipulation Interface) that uses object flow, the motion of the manipulated object alone, to link human demonstration video with simulated robot data, so robots learn without real-world robot training data. It is third-party research; Firsthand is not affiliated with its authors.
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What is Im2Flow2Act, and what problem does it solve?
Im2Flow2Act is named in Flow as the Cross-Domain Manipulation Interface (arXiv 2407.15208) by Mengda Xu, Zhenjia Xu, Yinghao Xu, Cheng Chi, Gordon Wetzstein, Manuela Veloso and Shuran Song, from Stanford University, Columbia University, J.P. Morgan AI Research and Carnegie Mellon University, first submitted on 21 July 2024 and last revised on 4 October 2024. The official repository labels it a CoRL 2024 paper. The abstract frames the problem as bridging two gaps: between embodiments, human and robot, and between environments, real world and simulation. The authors propose object flow as the manipulation interface that spans both.
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Where does Firsthand fit next to Im2Flow2Act?
Firsthand is not affiliated with the Im2Flow2Act authors and makes no claim that any model, Im2Flow2Act included, was trained on Firsthand data. Firsthand captures human egocentric video, custom collection, fast and on demand, to a written spec, with depth derived from a calibrated stereo rig, 3D hand pose at 21 joints per hand and 6-DoF IMUs at 200 Hz, delivered in RLDS, LeRobot format or WebDataset under a buyer-owned commercial license, with one task instruction per episode. Point tracks, optical flow, object flow, 2D or 3D trajectory labels, keypoint labels, robot trajectories, teleoperation data, synthetic data and language annotations beyond that instruction are not Firsthand deliverables.
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What is object flow, and why use it as the interface?
Per the paper, object flow is the exclusive motion of the manipulated object, excluding any background or embodiment. The authors list four benefits: it can describe rigid, articulated and deformable objects; it is independent of the agent’s embodiment because it describes the change an action causes rather than the action; it focuses on motion rather than appearance, which they say reduces the sim-to-real gap; and it is interpretable, so a person can read and select a flow.
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How do the two components of Im2Flow2Act work?
The flow generation network is trained on human demonstration videos. Given the initial scene image and a task description, it generates the complete object flow for the task once, at the start. The authors build it on the AnimateDiff video generation model, detect the object with Grounding DINO and track keypoints with TAPIR.
The flow-conditioned policy is trained on simulated robot play data. It takes the generated flow, the current tracked keypoints and the robot’s proprioception, and outputs a 6-DoF end-effector position and a 1-DoF gripper state through a diffusion action head. A temporal alignment module estimates the remaining flow from task progress.
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What data did the authors use?
Per the paper, no real-world robot data is collected. The robot side uses simulated exploration: the authors report 4,800 random exploration trajectories from a UR5e robot in MuJoCo, across rigid, articulated and deformable objects. The human side is real-world hand demonstration video for four tasks, recorded with a RealSense camera at 30 FPS. These are the authors’ figures, and Firsthand has not verified them.
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What did the authors report about results?
The authors evaluate four real-world tasks: pick-and-place, pouring, opening a drawer and folding cloth. They report an average success rate of 81% across the four, and, in their Table 2 for language-conditioned execution, 90%, 80%, 85% and 70% respectively. They also report that the method outperforms ATM by an average of 30% across four simulated tasks. These are the authors’ figures, measured on their setup; Firsthand has not verified or reproduced them.
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What limitations do the authors state?
Per the paper, 2D flow is ambiguous for 3D actions, with pouring failures tied to imprecise movement along the camera depth axis, and it struggles with out-of-plane rotation such as screwing. Simulating deformable objects remains hard, which the authors link to a drop in cloth folding. The system assumes a camera viewpoint calibrated between simulation and testing, flow as an abstraction limits dexterous tasks such as in-hand manipulation, and it relies on accurate object detection.
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How does Im2Flow2Act compare with Track2Act, ATM and trajectory data?
The first table sets Im2Flow2Act beside three site entries. The Im2Flow2Act paper discusses both Track2Act and ATM, and its comparisons are the authors’ own. It does not discuss Firsthand trajectory data, which is a measured wrist and hand path, a different object from generated image-space flow.
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What data does an Im2Flow2Act-style approach need, and what does Firsthand state?
Per the paper, the flow stage needs human demonstration video plus a task description, and an initial depth image gives 3D keypoints at the start. The paper does not state whether egocentric capture would work in the video role, so that is Not stated. It also records the demonstrations with a fixed RealSense camera and assumes a calibrated viewpoint.
Firsthand states real human egocentric capture with one task instruction per episode and depth derived from a calibrated stereo rig. That is a note about format, not a claim of compatibility, and any object flow would come from tools the buyer runs, not from Firsthand.
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When do you need fast, on-demand custom collection instead?
When a program needs real human demonstrations that public or synthetic data does not cover, specified field by field. Firsthand does not build or train models. Confirm the fields on a Spec Pilot, a small fast first batch; the median from signed spec to first validated batch is 48 hours where coverage is deep, three to four weeks where thin.
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Im2Flow2Act at a glance, as stated in the paper
| Item | What the paper states |
|---|---|
| Paper | Flow as the Cross-Domain Manipulation Interface (arXiv 2407.15208); the framework is named Im2Flow2Act |
| Authors | Mengda Xu, Zhenjia Xu, Yinghao Xu, Cheng Chi, Gordon Wetzstein, Manuela Veloso and Shuran Song |
| Affiliations | Stanford University, Columbia University, J.P. Morgan AI Research and Carnegie Mellon University |
| Submitted | 21 July 2024; last revised 4 October 2024 (version 2) |
| Core idea | Use object flow as the manipulation interface across embodiments and environments |
| Component 1 | A flow generation network trained on human demonstration videos, conditioned on the initial image and a task description |
| Component 2 | A flow-conditioned policy trained on simulated robot play data |
| Real-world robot training data | None, per the authors |
| Code | Official repository: real-stanford/im2Flow2Act on GitHub |
| Firsthand relationship | None |
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Im2Flow2Act beside the Track2Act, ATM and trajectory data entries
| Site entry | What the entry states | How Im2Flow2Act relates (sources read) |
|---|---|---|
| Track2Act | A published method that predicts 2-D point tracks from an initial and a goal image, then refines the plan with a residual policy trained on a small set of robot demonstrations | The Im2Flow2Act authors say Track2Act still requires real-world robot data and cite it for a heuristic flow-to-action baseline; Im2Flow2Act uses a learned policy trained on simulated data |
| Any-point Trajectory Modeling (ATM) | A published method that pre-trains on action-free video to predict future 2-D tracks of arbitrary points | The authors say ATM predicts grid flow that captures embodiment motion and still needs in-domain robot data from teleoperation; Im2Flow2Act generates only object flow, once, from the initial frame |
| Trajectory data | The recorded path of a wrist or hand over time, delivered as 6-DoF IMU streams at 200 Hz and 3D hand joints beside the video | Im2Flow2Act flow is generated image-space motion of an object; it is not a measured wrist or hand stream |
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What Im2Flow2Act consumes beside what the Firsthand site states
| Aspect | Im2Flow2Act (sources read) | What the Firsthand site states |
|---|---|---|
| Human video | Real-world human hand demonstrations for each task, recorded with a RealSense camera | Human egocentric video, custom collection |
| Task specification | A task description plus the initial scene image | One task instruction per episode |
| Object flow and keypoints | Produced by running Grounding DINO and a point tracker over the videos | Not a Firsthand deliverable |
| Robot data | Simulated exploration trajectories on a UR5e robot; no real-world robot data | Robot trajectories, teleoperation data and synthetic data are not Firsthand deliverables |
| Depth | An initial depth image gives 3D keypoints at the start | Depth derived from a calibrated stereo rig |
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Frequently asked questions
- What is Im2Flow2Act?
- A published framework (arXiv 2407.15208) that uses object flow as the interface between human demonstration video and a robot policy trained in simulation, with no real-world robot training data. It is third-party research.
- What is object flow in Im2Flow2Act?
- Per the paper, the motion of the manipulated object alone, excluding any background or embodiment, which makes it independent of whether a human or a robot acts.
- What results do the authors report?
- An average success rate of 81% across four real-world tasks, per the authors. These are the authors’ figures; Firsthand has not verified them.
- How does Im2Flow2Act differ from ATM?
- Per the authors, ATM predicts grid flow that also captures embodiment motion and needs in-domain robot data, while Im2Flow2Act generates only object flow and uses simulated robot data.
- Does Firsthand use Im2Flow2Act, and can I request a custom dataset?
- Firsthand is not affiliated with the Im2Flow2Act authors and claims no use, training or compatibility. Point tracks, optical flow, object flow, trajectory labels, robot trajectories and teleoperation data are not Firsthand deliverables. You can request a custom dataset.
Related terms
Sources
- Flow as the Cross-Domain Manipulation Interface (arXiv 2407.15208)
- Im2Flow2Act (official project page)
- real-stanford/im2Flow2Act (official GitHub repository)
- AnimateDiff (arXiv 2307.04725)
- Grounding DINO (arXiv 2303.05499)
- TAPIR (arXiv 2306.08637)
- Any-point Trajectory Modeling for Policy Learning (arXiv 2401.00025)
- Track2Act (arXiv 2405.01527)