GuideIntermediate12 min
Export OBJ and MTL for mesh workflows
Choose units, axes, origin, structure and appearance for OBJ, keep its companion files together and import it reliably in common tools.
- Applies to
- Current Prism release · Navisworks Manage 2025–2027
- Availability
- Free and higher
- For
- Visualization, DCC and real-time teams
- Last reviewed
What the OBJ package contains
- Triangulated faces plus optional source lines and points.
- Per-corner normals according to the selected normal mode.
- A sibling .mtl with diffuse color and opacity when materials are enabled.
- Stable ASCII-safe object/group names for exported elements and source organization.
- Optional JSON/CSV attributes joined to emitted group names when the requested companion is verifiably available.
Choose units, axes and structure
| Receiver | Prism unit / axis | Import check |
|---|---|---|
| Blender | Metres, Z-up | Scale 1; avoid an extra up-axis rotation. |
| 3ds Max | Metres or centimetres, Z-up | Match the OBJ import unit. |
| Rhino | Metres or millimetres, Z-up | Set document/import units first. |
| Unity | Metres, Y-up | Scale 1; Prism performs the axis conversion. |
| Unreal Engine | Centimetres, Z-up | Scale 1 when one Unreal unit is one centimetre. |
- Use Federation center for smaller, more stable coordinates in DCC and real-time tools; Preserve world only when absolute coordinates are required.
- Use Source model for manageable organization, Element for object-level selection, or Single mesh when selection structure is not needed.
- Keep triangle ratio at 100% for the first compatibility test. Lower values apply deterministic simplification and rebuild normals.
Keep the output set together
- Do not separate or independently rename the .obj and .mtl; the OBJ references the MTL by base name.
- Keep requested .attributes.json/.csv companions with the same delivery record.
- For per-source output, import all files under the same origin and scale. Prism centers the federation once so the files remain aligned.
- Include the report so the receiver can see unit, axis, removed origin, structure and simplification choices.
Troubleshoot OBJ import
| Symptom | Cause | Fix |
|---|---|---|
| 100× or 1000× scale error | Receiver assumes a different unit | Set the import unit to the Prism choice and remeasure a known length. |
| No colors | MTL missing or material import disabled | Place the matching .mtl beside .obj and enable material loading. |
| Transparency looks opaque | Receiver render mode ignores MTL opacity | Enable its transparent material mode; Prism writes opacity as d. |
| Model is unstable/far away | Large preserved world coordinates | Use Federation center and retain the removed origin in the report. |
| File is very large | OBJ expands repeated placements | Use source splits or a target with instancing; reduce triangles only after fidelity testing. |
Related guidance
Choose an export format and compatible settingsCompare Prism output formats, plan availability, packaging, coordinate conventions and the most important interoperability limits.Export glTF 2.0 and GLBPackage a portable real-time scene with predictable metres, Y-up coordinates, structure, appearance and validation.Validate an export and read the reportsConfigure Prism checks, IDS validation, halt-on-blocking policy, HTML/JSON/CSV reports and BCF issue output, then decide whether a result is deliverable.