Models, splats and video
USD, IFC and STEP models
Open a USD stage fully composed (references, payloads, variants, prototypes and instancing resolved), an IFC building or a STEP part, switch components on and off, fly to any of them, and measure a scan against the model’s surface.
Opening and viewing are free. Exporting a USD stage or a glTF is Pro.
Part of Scan to BIM, Benchmarks, Autodesk ReCap alternative.
When to use it
To check an as-built scan against the design model, to walk a factory or a building model that nothing else on the desk opens quickly, or to draw a floor plan straight from an IFC.
Step by step
- Open a
.usd,.usda,.usdcor.usdz, an.ifc, or a.step/.stpwith File › Open…, or add it to a scan with File › Add Layer…. - A USD stage is composed on load. The first open of a large stage takes time; N3D writes a mesh cache beside it, and every later open reads that cache.
- In the Scene pane, expand the model row:
n of m components, grouped by the model’s own paths. Each component and each group has an eye; groups have hide all, hide rest and show all. - Hover a component to see its triangle count; double-click it (or double-click the model in the view) to fly to it. Picking only hits visible components, so hiding a wall reaches the pipe behind it.
- Switch the shading in Properties › Mesh display: Shaded, Albedo, Normals or Flat.
- To measure a scan against the model, add the scan as the measured cloud and the model as the reference in Compare: the distance is point-to-triangle, to the surface itself.
- From an IFC, Process › Floor plan… and Scene graph & spaces… read the model’s own storeys, rooms, walls and openings.
What it was measured at
On a 38-layer factory stage, N3D and OpenUSD 26.8 report the same 65,654 meshes, the same 15,217,537 triangles and the same bounding box to the millimetre. First open 59.3 s; every reopen 1.64 s. An IFC of 100,871 entities meshes in about 1 s.
From the command line
n3d-render-cli render --input stage.usda --list-parts # the component table
n3d-render-cli render --input stage.usda --hide-part Block_D --out view.png
n3d-render-cli export-usd --input scan.las --out scan.usda --y-up # write a USD stage (Pro)Limits, stated
- Composing a very large stage the first time is memory-heavy: 6.5 GB peak for a 900,000-prim stage, composed one branch at a time on one thread to keep it there.
- A truncated or structurally damaged stage is refused before it is opened. One class of corruption inside a binary layer’s value region can still end the process; it is recorded, not hidden.
- Component trees are built for USD; IFC and STEP open as one model, and double-click flies to the surface under the cursor.
classprototypes are templates and are correctly left undrawn;GeomSubsetchildren are provenance and contribute no triangles.
Related questions
Which file formats can N3D open?
Point clouds: LAS (PDRF 0 to 10), LAZ, COPC, E57 (multi-scan, with panoramas), PLY, PCD, NPY and ASCII .xyz .pts .asc .txt .csv, whose column layout is detected from the values. Splats: PLY and SPZ. Models: IFC (2x3 and 4), STEP (AP203, AP214), USD (.usd .usda .usdc .usdz), glTF / GLB, OBJ and STL. Drawings: GeoJSON, Shapefile, DXF, SVG and CityGML. The format matrix gives what each one carries and how fast it opens.
Do I need a lot of memory?
Less than the file size. Point clouds are indexed out of core and streamed, so a cloud larger than your RAM still opens. Composing a large USD stage for the first time is the heaviest case measured: 6.5 GB peak for a 900,000-prim stage, after which every reopen reads a cache in 1.64 s.
More in the FAQ.