What is the M3D file format?
.m3d files store 3D object models and are associated with DIALux, the professional lighting design and planning software developed by DIAL GmbH.
DIALux is a lighting-design tool, not a general architectural modelling application. It focuses on natural and artificial light modelling and visualisation, letting designers specify luminaires, light sources, and scene objects to calculate illuminance and produce realistic renders. .m3d files store the 3D geometry of furniture and scene objects - chairs, desks, walls, plants, and similar items - that populate a room or outdoor area in a DIALux project. A preview thumbnail is embedded alongside the mesh so objects appear correctly in the DIALux Furniture library browser.
Typical workflow: model geometry in a CAD application, export to SAT or 3DS format, import into DIALux (applying a ÷1000 scale correction if coming from AutoCAD/SAT), then save as .m3d for the Furniture library. .m3d files can be reused across different projects that support the format. Project renders can be exported to JPG images.
Note that the .m3d extension is also used by several unrelated 3D engines and games; within the context of lighting design it always refers to the DIALux object format.
Security & safety
RISK: LOWA DIALux .m3d is passive 3D model data, not executable, so it is low risk to handle. The main caution is provenance: download object libraries from reputable DIALux community sources, since 'free DIALux object' searches lead to many ad-heavy mirrors. Also confirm a downloaded .m3d is really a DIALux object and not a same-extension game model, which DIALux won't load.
Format details
in a nutshell- Model 3D (M3D) open mesh format - An open, documented .m3d 3D mesh container (bztsrc/M3D) used by some engines/tools - unrelated to DIALux.
- Motor3D / various game model files - Several 3D engines and older games use .m3d for their own proprietary model meshes.
- Rinzo / 3D landscape model exports - A few CAD/landscape tools also emit .m3d model files in their own format.
Programs that open M3D files
Windows2 apps
Dialux evo
Free Drag the .m3d into the object/Furniture library, or Import 3D object; it appears under Furniture to place in the scene.
DIALux 4
Free Use the older DIALux 4 if the object was made for it; import the .m3d into the furniture list. Technical details
deep spec| Format type | Proprietary binary 3D object model for DIALux lighting projects |
| Developer | DIAL GmbH (DIALux lighting design software) |
| Encoding | Binary (proprietary DIALux container) |
| Compression | Proprietary/internal (details not publicly documented) |
| Typical size | Tens of KB to a few MB (depends on mesh complexity) |
| Associated OS | Windows |
| Content | 3D mesh geometry of a scene/furniture object plus an embedded preview thumbnail image |
| Version compatibility | DIALux 4 and DIALux evo both use .m3d; file compatibility is version-dependent |
| Graphics | No lighting or print data - only structural mesh geometry and a preview thumbnail |
| Import path | Created by importing .sat or .3ds geometry into DIALux and exporting to .m3d for the Furniture library |
| Scale note | Objects imported from AutoCAD/SAT often require a ÷1000 scale correction before saving as .m3d |
| Reusability | .m3d objects are stored in the DIALux Furniture library and can be shared across projects |
| MIME type | application/octet-stream (no registered MIME) |
| Released | With the DIALux 4 furniture/object library (2000s) |
| Latest version | Tied to DIALux 4 / DIALux evo object libraries |
| Specification | www.dialux.com |
M3D conversions
Community Q&A
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