Physical AI Neural Reconstruction (NuRec) Router

Purpose

This is a thin router for NVIDIA Neural Reconstruction (NuRec) requests. It points at the upstream nurec-index skill at https://github.com/NVIDIA/nurec-skills and its sibling skills (physical-ai-datasets, ncore, nre, asset-harvester, nurec-fixer). Use this skill to:

Identify which upstream sibling skill answers a NuRec question.
Locate, clone, or refresh the canonical nurec-skills checkout.
Order multi-step NuRec workflows (data → conversion → train → render → cleanup) before opening the upstream recipe.

The canonical recipes (training, rendering, data conversion, dataset downloads, object harvesting, frame cleanup) live in the upstream sibling skills. Never copy or reconstruct their commands here.

Do NOT use this skill for:

SimReady packaging of CAD or source meshes → use omniverse-cad-to-simready.
Generic USD performance tuning unrelated to NuRec → use omniverse-usd-performance-tuning.
AKS / OSMO / NIM Operator infrastructure setup → use physical-ai-infrastructure-setup-and-resilient-scaling.

When to Use

Read this skill first whenever a user mentions any of:

nurec, nurec router, nurec index, neural reconstruction, neural reconstruction engine, NRE, 3DGUT, 3DGRT, USDZ, NCore V4, sensorsim, sensor sim, novel view synthesis, PhysicalAI-Autonomous-Vehicles-NuRec, PhysicalAI-Robotics-NuRec, PhysicalAI-NuRec-PPISP, Cosmos-Drive-Dreams, asset harvester, nurec fixer, DiffusionHarmonizer, harmonizer, difix, difix3d, carline adaptation, serve-grpc, render-grpc, warm serve-grpc, nre thin client, batch_render_rgb, nurec teardown, "where do I start with NuRec", "which NuRec skill should I use for X?".

Decide which upstream sibling skill answers the question, fetch it (see Locate and fetch the upstream skills), then follow that skill's body.

Prerequisites

The router itself has no runtime prerequisites beyond git for fetching the upstream. Downstream sibling skills need Linux x86_64, an NVIDIA GPU (Ampere+, CUDA 12.8, >= 24 GB VRAM), Docker plus the NVIDIA Container Toolkit, an NGC API key, a Hugging Face token with the relevant gated licenses already accepted, and Python 3.10+.

Full per-skill detail — driver floors, container names, key resolution order, which Hugging Face assets are gated, and how to verify secrets without echoing them — is in references/prerequisites.md. Prefer each sibling's scripts/validate_setup.py over hand-written checks.

What is NuRec?

NuRec (NVIDIA Omniverse Neural Reconstruction) turns camera, LiDAR, radar, or stereo recordings — typically from a self-driving car or a robot — into a 3D scene that can be re-rendered from any viewpoint. A typical project runs in three stages: get the input (convert a recording with ncore, or download a ready-made dataset with physical-ai-datasets), train the reconstruction (nre, which emits a USDZ), then render new views (nre). Projects that only want to use a scene NVIDIA already published skip the training stage.

Background on the vocabulary — NRE vs NuRec, USDZ, NCore V4, 3DGUT / 3DGRT — is in references/what-is-nurec.md.

Pick a skill

Match the user's goal in the left column and open the named upstream skill on the right. Arrows mean "do these in order".

I want to…	Upstream skill
Find or download a NuRec dataset NVIDIA has published	`physical-ai-datasets`
Convert my own camera / LiDAR / radar / depth / stereo recording into NCore V4	`ncore`
Write a new converter for an unsupported sensor setup (drone, RGB-D, ROS 2 bag, COLMAP, ScanNet++)	`ncore`
Train a 3D reconstruction from an NCore clip	`ncore` → `nre`
Generate the extra inputs NRE needs (segmentation masks, depth, ego mask, DINOv2, LiDAR-seg visibility)	`nre` (uses the `nre-tools-ga` container)
Render a USDZ along the original camera positions	`nre`
Render at full resolution / highest quality	`nre` (see "Quality presets")
Render along a shifted trajectory (e.g. car moved 3 m left)	`nre`
Adapt an existing USDZ to an augmented target-vehicle rig (carline adaptation)	`nre` (`export-custom-rig-trajectory` → `render`) → `nurec-fixer`
Render through a server so CARLA / Isaac Sim / AlpaSim / a custom simulator can ask for frames	`nre` (`serve-grpc`)
Render the same USDZ many times back-to-back from Python with minimal per-call latency	`nre` (warm `serve-grpc` + thin Python client / `batch_render_rgb`)
Render LiDAR sweeps (point clouds) from a USDZ	`nre` (`render-grpc --lidar`)
Skip training and just render a NuRec scene NVIDIA already built	`physical-ai-datasets` → `nre`
Skip training and use a pre-built indoor robotics scene	`physical-ai-datasets` → `nre` (then Isaac Sim 5.1)
Extract individual 3D objects (cars, pedestrians) from a driving clip	`asset-harvester`
Add, remove, or replace cars / pedestrians in a NuRec scene	`asset-harvester` → `nre`
Clean up or harmonize rendered frames (ghosting, floaters, flicker, lighting/shadows)	`nurec-fixer`, or `--enable-difix` inside `nre` for inline rendering
Export the scene as a PLY, mesh, depth maps, ego mask, etc.	`nre`
Upgrade an old USDZ so newer NRE versions load it faster	`nre` (`upgrade-artifact`)
Open a USDZ or PLY in a browser viewer	`nre` (`viewer` / `ply_viewer`)
Measure rendering quality (PSNR, SSIM, LPIPS) against ground truth	`nre` (`eval-rendering-metrics`)
Benchmark different reconstruction methods on the same scenes	`physical-ai-datasets` (`PhysicalAI-NuRec-PPISP`) → `nre`
Train on multiple GPUs or on SLURM	`nre`

Common workflows

Seven end-to-end workflows are documented in references/workflows.md, lettered to match the upstream nurec-index workflow IDs:

A. Make a NuRec scene from your own recording.
B. Use a NuRec scene NVIDIA has already trained.
C. Use NuRec for indoor robot simulation.
D. Add, remove, or replace 3D objects in a scene.
E. Clean up rendered frames.
F. Benchmark reconstruction quality.
G. Connect NuRec to a simulator.

Open that file when the user's task spans more than one sibling skill.

Sibling skills (upstream)

Refer to a sibling by its name — that is the portable identifier. The folder column is where it lives in a local nurec-skills checkout, except where a repo is named — asset-harvester ships from its own product repo.

Name	Upstream folder	What it does
`physical-ai-datasets`	`skills/physical-ai-datasets/`	Catalog and download recipes for every NVIDIA Physical AI dataset on Hugging Face (driving, robotics, manipulation, NuRec scenes, benchmarks).
`ncore`	`skills/ncore/`	Converts any sensor recording to NCore V4 (the format NRE needs), upstream release `2026.04`. Also covers writing a new converter.
`nre`	`skills/nre/`	The Neural Reconstruction Engine itself (`nvcr.io/nvidia/nre/nre-ga`, `nvcr.io/nvidia/nre/nre-tools-ga`, NRE 26.04 — image tags `26.04.01` / `26.04` / `latest`). Trains, performs carline adaptation, renders (locally, via warm `serve-grpc` + thin Python client / `batch_render_rgb`, or to an external simulator), exports meshes / point clouds / depth, edits actors, evaluates quality.
`asset-harvester`	`NVIDIA/asset-harvester` → `skills/asset-harvester/`	Open-source Apache-2.0 pipeline (SparseViewDiT + TokenGS) that extracts individual 3D objects from sparse views in a driving clip and saves them as `.ply` Gaussian splats, optionally emitting `metadata.yaml` for the NuRec handoff.
`nurec-fixer`	`skills/nurec-fixer/`	Standalone NVIDIA DiffusionHarmonizer workflow — public successor to the older Fixer / Difix3D+ recipes — that cleans rendered frames, harmonizes inserted actors, evaluates PSNR/LPIPS, and optionally fine-tunes the model.

For naming overlaps (NRE vs Fixer, ncore vs nre, AV-NuRec vs Cosmos-Drive-Dreams, NuRec vs SimReady) see references/mix-ups.md.

Locate and fetch the upstream skills

Try the local disk first, in this order — a sibling skill already installed in the runtime is preferable to a network fetch. This applies to the nurec-skills-hosted siblings; asset-harvester is fetched from its own repo (see references/upstream-fetch.md):

.agents/skills/<name>/SKILL.md (Cursor, Codex, NemoClaw)
.claude/skills/<name>/SKILL.md (Claude Code)
.cursor/skills/<name>/SKILL.md (project-scoped)
~/.cursor/skills/<name>/SKILL.md (personal skills)
An existing nurec-skills clone under the shared upstream root.

This order covers the nurec-skills-hosted siblings only. asset-harvester is not among them — see references/upstream-fetch.md.

Only if none of those exist, ask the user for explicit consent before cloning. A git clone is a network fetch of an external repository plus a write to the local filesystem; it can violate org network policy and carries supply-chain risk. Show the user what you intend to run and wait for a yes.

Quick recipe (full version, including the pinned-commit layout, in references/upstream-fetch.md):

UPSTREAM_ROOT="${NUREC_SKILLS_UPSTREAM_ROOT:-${PHYSICAL_AI_SKILL_HUB_UPSTREAM_ROOT:-$HOME/.physical-ai-skill-hub/upstreams}}"
mkdir -p "$UPSTREAM_ROOT"
if [ -d "$UPSTREAM_ROOT/nurec-skills/.git" ]; then
  git -C "$UPSTREAM_ROOT/nurec-skills" fetch --tags
  git -C "$UPSTREAM_ROOT/nurec-skills" checkout main
  git -C "$UPSTREAM_ROOT/nurec-skills" pull --ff-only
else
  # Only after the user has agreed. Prefer --branch <tag-or-sha> over HEAD.
  git clone --depth 1 https://github.com/NVIDIA/nurec-skills.git \
    "$UPSTREAM_ROOT/nurec-skills"
fi
test -f "$UPSTREAM_ROOT/nurec-skills/skills/nurec-index/SKILL.md"

The upstream tree is rooted at skills/<name>/SKILL.md; .agents/skills is a symlink onto skills/, so either path resolves. Read the upstream skill before running any mutating command:

cat "$UPSTREAM_ROOT/nurec-skills/skills/nurec-index/SKILL.md"  # upstream router
cat "$UPSTREAM_ROOT/nurec-skills/skills/<folder>/SKILL.md"     # sibling

Companion files (references/, scripts/, assets/) ship inside the sibling's own skill directory, alongside its skill definition — not next to this router.

Hard Rules

Router only — do not duplicate upstream NuRec recipes here. Read the upstream sibling skill body before running any mutating command.
Refer to sibling skills by their name: (e.g. nre), not by repo path. Folder layouts can change; the name is portable.
Never git clone the upstream without explicit user consent. For the nurec-skills siblings, exhaust the local lookup order first, show the exact command, and clone only into a path the user agreed to — never silently into /tmp. Do not scan broad developer workspaces such as ~/Codes or reuse unrelated old clones.
Use the GA container channel: nvcr.io/nvidia/nre/nre-ga and nvcr.io/nvidia/nre/nre-tools-ga. The un-suffixed nvcr.io/nvidia/nre/nre / nre-tools names are the legacy channel — still valid for cached version pins, but not what a new workflow should pull.
Resolve the NGC key as ${NGC_CLI_API_KEY:-${NGC_API_KEY:-}} and log in with docker login nvcr.io --username '$oauthtoken' --password-stdin. Never echo a key.
physical-ai-datasets covers gated Hugging Face datasets. Do not bypass dataset license terms; the user must accept the PhysicalAI-* gated licenses on Hugging Face and provide a token before downloading.
Asset Harvester runs before packaging into a USDZ. Do not call nre's export-external-assets on hand-rolled .ply files unless the user explicitly asks to skip Asset Harvester.
For artifact cleanup, prefer the built-in --enable-difix path in nre. Route to the standalone nurec-fixer only when the user needs the public code/model card, paired evaluation, fine-tuning, or fixes on previously rendered frames.
Do not invent NRE / NCore / DiffusionHarmonizer commands from memory. Re-read the upstream sibling skill — versions move fast (NRE 26.04 — pull nvcr.io/nvidia/nre/nre-ga:26.04.01 or :26.04; the release name release_26.04 is not a valid image tag — and NCore 2026.04 are the current pins).
This router does not deploy infrastructure. Route AKS / OSMO / NIM Operator setup to physical-ai-infrastructure-setup-and-resilient-scaling.

Limitations

Router only. This skill never executes mutating NuRec commands. All training, rendering, conversion, and harmonization happens in upstream sibling skills.
Upstream-pinned. Most recipes live in https://github.com/NVIDIA/nurec-skills; asset-harvester lives in https://github.com/NVIDIA/asset-harvester, which evolves outside this repo. Stale clones can drift; always refresh the upstream before relying on a sibling skill.
Hand-curated catalogue. A newly-added upstream sibling is not discoverable here until someone edits the tables (see references/maintenance.md).
Gated content. nvidia/PhysicalAI-*, nvidia/Harmonizer, and nvidia/Cosmos-Predict2-0.6B-Text2Image require the user to accept license terms on Hugging Face first. For asset-harvester only its optional DINOv3, Llama Guard and SAM 3D Body models are gated. The router cannot bypass this.
Heavy footprint. A complete NuRec workflow can leave 150 GB+ on disk. See references/teardown.md.
NVIDIA-only stack. Requires Linux x86_64 plus an NVIDIA GPU and the NVIDIA Container Toolkit. aarch64 / AMD / Intel / Apple Silicon are not supported.
No Omniverse / Isaac Sim integration steps. Handing a USDZ to Isaac Sim 5.1 (workflow C) is documented in the Isaac Sim docs, not in the NuRec skill family.
Not a SimReady pipeline. NuRec produces a renderable USDZ from a recording; SimReady packaging of CAD or source meshes is a different pipeline (see omniverse-cad-to-simready).

Troubleshooting

Routing-level symptoms — a missing upstream clone, gated-asset 403s, NGC login failures, manifest unknown on an NRE image, stale cached skill names — are tabulated in the troubleshooting companion file that ships alongside this skill. Symptoms specific to a sibling's own commands belong to that sibling's skill.

Cross-skill teardown

A complete NuRec workflow can leave 150 GB+ on disk between container images, model weights, code clones, conda envs, and output directories. Each sibling skill has its own dedicated Teardown section — read them in the order documented in references/teardown.md when the user no longer needs the workflow. Do not revoke NGC_API_KEY / HF_TOKEN as part of teardown unless they were leaked.

Keeping this router up to date

Procedure for adding new sibling skills, renames, or upstream URL changes lives in references/maintenance.md. Treat the upstream nurec-index at https://github.com/NVIDIA/nurec-skills/blob/main/skills/nurec-index/SKILL.md as authoritative for the routing taxonomy and workflow ordering; this skill mirrors only the picker tables, the workflow ordering, and the upstream fetch recipe. It is not authoritative for asset-harvester, which is maintained in https://github.com/NVIDIA/asset-harvester.

physical-ai-neural-reconstruction