Appearance
To archive 3D models long term you should never keep just one file. The defensible approach is a small bundle per object: an open-standard mesh (PLY, OBJ, or glTF/glb for textured models), the original source photographs, a checksum for every file, and a plain documentation record covering scale, capture details, and software settings. Formats and viewers will change over a decade; a documented bundle of open formats plus the raw inputs is what survives.
Why is a single 3D file never enough?
A photogrammetric model is a derivative, not an original. The mesh you export today was produced by a specific version of specific software with specific settings, and a better reconstruction may be possible in five years. If you preserve only the finished .obj, you have frozen one interpretation of the object. Preserve the photographs and you preserve the ability to rebuild — and to rebuild better. Treat the images as the preservation master and the mesh as an access derivative.
What should go in an archival package?
Build one folder per object containing layered fallbacks, so a failure at any level still leaves something usable.
text
hartley-corbel-2024-031/
masters/
photos/ # original RAW or full-quality JPEG, untouched
targets/ # coded-target / scale-bar images
derivatives/
model.ply # geometry, open, no texture dependency
model.glb # textured, open, web-ready
model.obj+mtl # widely supported textured fallback
documentation/
capture-report.pdf
processing-report.txt # software, version, settings, GCPs
README.txt
checksums.sha256The principle is graceful degradation: even if every viewer that reads .glb disappears, the .ply geometry and the source photos remain openable.
Which formats survive a decade?
| Format | Role | Open? | Texture | Archival note |
|---|---|---|---|---|
| PLY | Geometry master | Yes | Vertex colour only | Simple, stable, well-documented |
| OBJ + MTL | Textured fallback | Yes | External maps | Ubiquitous, text-based, easy to recover |
| glTF / glb | Textured access | Yes | PBR maps embedded | Open Khronos standard, web-friendly |
| FBX | Avoid as only copy | No | Yes | Proprietary, version-fragile |
Metashape .psx | Convenience only | No | N/A | Version-locked project, never sole copy |
Store at least one geometry-only and one textured open format. Keep proprietary project files only as a bonus.
How do I protect against silent corruption?
Bit rot is the quiet killer of 3D archives because nobody opens a model for years. At ingest, compute a SHA-256 for every file and write it into the package:
bash
# create a manifest at ingest
sha256sum masters/photos/* derivatives/* documentation/* > checksums.sha256
# verify it later, on a schedule
sha256sum -c checksums.sha256Run the verification on a fixity schedule (annually at minimum), keep at least two geographically separated copies, and never let your only copy live on a single disk. This is the 3-2-1 rule applied to meshes.
What metadata makes a mesh scholarly rather than decorative?
A model with no scale or provenance is an ornament. Capture, at minimum: object identity and accession number; who captured it, when, and with what camera; the units and a known scale reference; the coordinate system if georeferenced; the software, version, and key settings; and the rights/licence. Embed what you can in glTF asset extras, but always keep a human-readable sidecar too, because embedded metadata is the first thing lost in a format migration.
How does archiving 3D differ from archiving images?
Three things make 3D harder. First, scale: a JPEG is self-contained, but a mesh is meaningless without units and a scale bar. Second, dependency chains: textured OBJ files reference external .mtl and image maps that get separated during careless copying. Third, derivation: you must preserve the inputs because the output is reconstructable and improvable. Plan for all three at ingest, not at retrieval.
Key Takeaways
- Archive a bundle, never a single file: open mesh + source photos + documentation + checksums.
- Treat the photographs as the preservation master; the mesh is a rebuildable derivative.
- Use at least one geometry-only open format (PLY/OBJ) and one textured open format (glTF/glb).
- Keep proprietary project files only as convenience copies, never as the sole record.
- Compute SHA-256 at ingest and verify on a fixity schedule to catch bit rot early.
- Record scale, units, provenance, and software settings, both embedded and as a sidecar.
- Apply 3-2-1: multiple copies, multiple locations, at least one offline.
Frequently Asked Questions
What is the best file format to archive a 3D model long term?
There is no single winner, so archive a small bundle: an open exchange mesh (PLY or OBJ, or glTF/glb for textured models), the raw photographs, and a plain-text or PDF/A documentation file. Avoid proprietary project files as the only copy.
Should I keep the source photographs as well as the mesh?
Yes. The photographs are the true preservation master because any mesh can be rebuilt from them with better software later. Store them as the original camera files (RAW or full-quality JPEG) alongside the derived model.
Do I need to keep the Metashape or RealityCapture project file?
Keep it as a convenience copy but never rely on it alone. Project files are version-locked and proprietary, so a future version may not open them. The open mesh plus photos plus a processing report is what guarantees long-term recovery.
How do I make sure an archived 3D model has not silently corrupted?
Generate a checksum (SHA-256) for every file at ingest, store it with the package, and re-verify it on a schedule. Any mismatch flags bit rot before it spreads to your only good copy.
What metadata should travel with an archived 3D model?
Record what the object is, who captured it and when, the scale and units, the coordinate reference, the software and settings used, and the licence. Without scale, units, and provenance a mesh is decorative rather than scholarly.
Is glTF a safe archival format?
glTF/glb is excellent for delivery and increasingly acceptable for archiving textured models because it is an open, well-specified standard. Pair it with a geometry-only PLY or OBJ so you are not dependent on a single format for the shape itself.