sim-runner

Apps & Automation

Run SAPIEN-based simulation rendering from EmbodiedGen layout outputs using sim-cli. Use this skill whenever users ask to load a generated layout.json into simulation, render interactive scene videos, control camera/render settings, or enable robot grasp trajectory rendering.

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How to use this skill

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Source SKILL.md: https://github.com/HorizonRobotics/EmbodiedGen/blob/HEAD/embodied_gen/skills/sim-runner/SKILL.md

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Sim Runner

Unified entry for EmbodiedGen simulation rendering via sim-cli.

When To Use

Use this skill when users want to:

Load a generated layout.json into simulation.
Render interactive scene videos (foreground + 3DGS background composition).
Adjust camera, rendering, or simulation-step parameters.
Include robot grasp trajectory rendering with --insert_robot.

Routing Rule (Core)

Use sim-cli when the input is an existing layout result (especially layout.json) and the target output is simulation visualization (e.g., Iscene.mp4), not generation of new assets/backgrounds/layouts.

Pre-checks

Run commands from the repository root.
Confirm the active environment is embodiedgen.
Confirm input --layout_path exists and points to a valid layout output.
Ensure referenced background and asset files in the layout directory are present.
If CLI commands are unavailable, run pip install -e . to register entrypoints.

Standard Command Template

sim-cli \
  --layout_path "outputs/layouts_gen/task_0000/layout.json" \
  --output_dir "outputs/layouts_gen/task_0000/sapien_render" \
  --insert_robot

Common Parameters

--layout_path: input layout file path.
--output_dir: output directory for rendered video.
--insert_robot: render robot grasp actions for manipulated objects.
--sim_freq --control_freq --sim_step: simulation/control timing settings.
--render_interval: render every N simulation steps.
--num_cameras --camera_radius --camera_height --fovy_deg: camera configuration.
--image_hw: output frame size.
--render_keys: render channels (requires Foreground for final compositing).
--ray_tracing: enable/disable ray tracing backend.
--device: rendering device (e.g., cuda).

Output Conventions

Primary output:

<output_dir>/Iscene.mp4

Typical input dependencies resolved from layout directory:

layout.json
background gs_model.ply
per-object assets referenced by layout

Runtime Expectations

Runtime depends on sim_step, render_interval, camera count, and ray-tracing mode.
Enabling --insert_robot increases render time due to grasp-action rollout.

Failure Handling and Retry

Missing file errors: verify layout-relative asset/background paths exist.
GPU memory pressure: reduce --num_cameras, --image_hw, or disable heavy settings.
Empty/invalid video output: ensure Foreground is included in --render_keys.
Slow runtime: reduce --sim_step or increase --render_interval.