File Formats — 3DF™, p3DF™, GLB, and USDZ

ModelLink 3D works with four file formats. Two are formats we created: 3DF™ (cloud-hosted) and p3DF™ (portable). Two are industry standards we build on: GLB (Khronos glTF) and USDZ (Apple AR Quick Look). This page explains what each format is, what it does, and how they fit together.

p3DF™ is the PDF of 3D

The shortest way to understand p3DF™ is by analogy.

Before PDF, sharing a formatted document meant the recipient needed the same software, the same fonts, and often the same operating system you used to create it. PDF solved that. One file, opens anywhere, looks the same on every device, no dependency on the application that created it.

3D has the same problem today. A SketchUp model needs SketchUp. A Revit model needs Revit. A GLB file needs a viewer that knows what to do with it. There is no single file you can email a client that contains the model, the way it should look, the AR experience, and the viewer to display it — all in one place, working offline, with no software to install.

p3DF™ is that file. It bundles the 3D model, its metadata, an embedded viewer, and AR support into one document that works anywhere a web browser works — including completely offline.

3DF™ is the cloud-hosted companion to p3DF™. The two formats serve different moments in the same workflow.

What is 3DF™?

Cloud-hosted

3DF™

3DF™ is ModelLink 3D's document format for packaging 3D models with their metadata, materials, and AR-ready assets for cloud-hosted delivery.

When you upload a model to ModelLink 3D, it becomes a 3DF™ document on our servers. The viewer that displays it, the AR launcher that places it in a customer's room, and the share link you send — all of those work against the 3DF™ document hosted on our platform.

3DF™ is designed for connected, live experiences: product pages, sales presentations, trade shows, gallery portfolios, anywhere a recipient has internet access and you want them to see the model in a polished, hosted viewer.

What is p3DF™?

Portable

p3DF™

p3DF™ is the portable companion to 3DF™. It is a self-contained file that bundles a 3D model, its metadata, an embedded viewer, and AR support into a single document that works offline, with no platform dependency.

You can email a p3DF™ file to a client. You can put it on a USB drive and hand it to a contractor. You can archive it for a project that needs to be reviewable five years from now whether or not any particular hosting service still exists. The recipient doesn't need an account, doesn't need to install software, and doesn't need to be online.

p3DF™ is designed for disconnected and archival use: customer deliverables, project documentation, offline presentations, long-term records.

How do 3DF™ and p3DF™ work together?

They are two profiles of the same underlying document concept, optimized for different deployment contexts.

3DF™ p3DF™
Purpose Cloud-hosted, connected delivery Portable, offline delivery
Where it lives On the ModelLink 3D platform Anywhere — email, USB, archive
Viewer Hosted viewer (we serve it) Embedded viewer (inside the file)
Requires internet? Yes No
Typical use Product pages, AR sharing, embeds Client deliverables, archival, offline
Created from Upload via plugin or web Generated from 3DF™ or exported directly

A single 3D model can be expressed as either format, depending on what you need to do with it. Most ModelLink 3D workflows start with 3DF™ for live sharing and produce a p3DF™ when the customer needs an offline copy or the project needs to be archived.

How does 3DF™ compare to GLB?

GLB is a 3D model. 3DF™ is a 3D document.

GLB is the binary form of glTF — an open standard maintained by the Khronos Group for representing 3D geometry, materials, and textures. It's excellent at what it does. Every modern 3D tool can read and write it.

What GLB does not do: carry metadata about who made the model, what project it belongs to, what SKU it represents, how it should be lit in a viewer, what its AR placement should look like, or which embedded viewer to render it in.

3DF™ adds all of that. A 3DF™ document contains a GLB as its underlying geometry, then wraps it with the metadata, materials configuration, AR assets, and viewer information needed to deliver a complete experience.

If GLB is the 3D model, 3DF™ is the 3D model plus everything you need to share it as a finished product.

How does p3DF™ compare to GLB?

Same answer as 3DF™, with one addition: p3DF™ also contains the viewer itself.

A GLB needs a viewer somewhere. A 3DF™ document points to a hosted viewer on ModelLink 3D. A p3DF™ document carries the viewer inside it, so the file works without any external service.

That's why p3DF™ is the format you reach for when offline operation matters.

How does USDZ fit in?

USDZ is Apple's format for AR Quick Look on iPhone and iPad.

When an iOS user taps "View in AR" on a ModelLink 3D viewer, Safari hands them a USDZ file and launches Quick Look.

Both 3DF™ and p3DF™ include a USDZ alongside the GLB. The GLB powers the interactive 3D viewer on every platform. The USDZ powers the AR experience on iOS specifically.

Android AR uses the same GLB through ARCore-compatible browsers. USDZ exists in the package specifically for the iOS path.

What's inside a 3DF™ or p3DF™ file?

At a high level:

For developers and implementers who need the full container structure, manifest schema, and version notes, see the 3DF™ specification document (forthcoming).

Frequently asked questions

How do I open a .p3df file?

Use the free P3DF™ Viewer at modellink3d.com/p3df-viewer/. Drag the file in (or tap to browse) and it opens in full 3D, with AR available on mobile. No account, no software to install — it runs in any modern browser, can be installed as an app, and works offline after the first visit.

The same link works for anyone you send the file to — include it alongside an emailed .p3df and the recipient is one drag away from the model. (A .3df document is the cloud-hosted profile — it's viewed through its ModelLink 3D share link rather than opened locally.)

Is 3DF™ proprietary?

3DF™ and p3DF™ are document formats created by ModelLink 3D. The trademarks are owned by Altonuva LLC. Specific terms governing third-party implementation are evolving as the formats develop.

What 3DF™ and p3DF™ are not: a closed lock-in mechanism. The 3D model inside every 3DF™ and p3DF™ document is a standard GLB file — the same open Khronos glTF format that every modern 3D tool can read. Your underlying model is never trapped.

Can I edit a 3DF™ file in standard 3D software?

You edit the source model in your 3D software of choice (SketchUp, Blender, etc.), then export to GLB and upload to ModelLink 3D, which produces the 3DF™ document. The 3DF™ document itself is a delivery and presentation package — it's not the working file you edit, just like a finished PDF isn't the Word document you edit.

If you need to make changes, you update your source model and re-export. The metadata and viewer settings on the ModelLink 3D platform persist across updates.

Does ModelLink 3D convert my GLB into a closed format?

No. ModelLink 3D packages your GLB into a 3DF™ document with metadata, viewer configuration, and AR assets around it. The original GLB is contained inside, unchanged and standard. You are not handing over your model to a format you can't get back out.

Is p3DF™ the same as a 3D PDF?

No. Adobe's 3D PDF was a 2D PDF document with a 3D model embedded in it, viewed inside Adobe Reader. Adobe largely abandoned 3D PDF development around 2010.

p3DF™ is a different approach: a 3D-first document with its own embedded web viewer, designed to run in any browser, on any modern device, without Adobe Reader or any other proprietary application. The analogy to PDF is about portability and self-containment, not about file structure or lineage. For the full argument, see The Case for p3DF.

Why .3df and .p3df as file extensions?

The extensions follow the same naming pattern as other established document containers: .docx, .epub, .usdz, .3mf. Short, format-identifying, recognizable. The .3df extension has been used historically by unrelated legacy software; current usage in any modern context refers to ModelLink 3D's 3DF™ document format.

Why is p3DF written with a lowercase p?

The format name is written as filed with the USPTO: lowercase p, uppercase 3DF. The lowercase prefix follows the naming pattern used elsewhere in technology for profile or variant indicators (e.g., iOS, ePub). The "p" stands for "portable."

Are 3DF™ and p3DF™ trademarked?

Yes. 3DF™ (USPTO serial 99772557) and p3DF™ (USPTO serial 99772582) are trademarks of Altonuva LLC, both filed 2026-04-18 with the United States Patent and Trademark Office. ModelLink 3D™ is also a filed trademark (USPTO serial 99772531, filed 2026-04-18). Patent applications covering the two-profile system and associated workflows have also been filed.

See also