# Dioptra: GLB 3D Model Viewer

> Dioptra: GLB 3D Model Viewer (iPhone/iPad app by Zachary Griffin.)

- Source: https://appshunter.io/ios/app/dioptra-glb-3d-model-viewer/id6812574588 (this page in markdown: same URL + `.md`)
- Developer: [Zachary Griffin](https://appshunter.io/developer/1813803229)
- Category: Productivity
- Price: $1.99
- Age rating: 4+
- Requires: iOS 17.0 · 5 MB
- Languages: American English
- Released: 2026-09-23
- Data updated: 2026-09-25
- User reviews in markdown: https://appshunter.io/ios/app/dioptra-glb-3d-model-viewer/id6812574588/reviews.md

## What is Dioptra?

A 3D model viewer for iPhone and iPad that takes measurement seriously.

Open a file, turn it over, and tap two points on the surface to get a real distance.

FORMATS
• glTF — .glb and .gltf
• USD — .usdz, .usdc, .usda and .usd
• STL — 3D prints and CAD exports, read in millimetres and turned upright
• PLY — scans and photogrammetry, with per-vertex colour
• VRM
• Interactive pages — an .html export keeps its own controls and runs as it was built

MEASURE
• Tap two points for a true distance
• Take as many measurements as you need; they stay listed with the model
• Switch between metric and imperial whenever you like
• Set what one file unit means: metres, centimetres, millimetres, inches or feet

INSPECT
• Orbit, pan and zoom, or leave it turning on its own
• Wireframe, to see how a mesh is built
• Studio, light and dark backgrounds
• Play embedded animations, one clip at a time
• Model info: width, height and depth, plus triangles, vertices, meshes, materials, textures, nodes and animations
• Share a snapshot of the view

ORGANISE
• Folders, which appear in the Files app exactly as they do here
• Search, sort by name, type or date, and switch between a list and a grid
• Rename, drag a model onto a folder to file it, or delete it
• Bring models in with the picker, from another app's share sheet, or by dropping them into the Dioptra folder in Files

SAMPLES
Six models come with the app, one for each kind of file it opens, all built to real-world scale: the ancient sighting instrument the app is named for, a Roman surveyor's groma, a sundial's gnomon, a tripod foot in millimetres, a surveyed patch of terrain, and an interactive plan of sight lines.

PRIVATE BY DEFAULT
No account, no sign-in, no cloud, no tracking and no ads. Your models stay on your device and everything works offline.


## Version history (last 1 release)

### 1.0 — 2026-09-23

No release notes.

## More apps by Zachary Griffin

- [Simple Client List](https://appshunter.io/ios/app/simple-client-list/id6745772350)
- [Pera Budgeting App](https://appshunter.io/ios/app/pera-budgeting-app/id6777862655)

All apps by Zachary Griffin: https://appshunter.io/developer/1813803229

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-25.*