Importing 3D Models
You are building a VR world and you want a soaring red-tailed hawk to circle above a canyon. You could spend weeks learning 3D sculpting software to build one from nothing — or you could find a hawk model someone already made, import it in seconds, and get back to building your world. Knowing how to find, choose, and import 3D models is one of the most powerful skills in AR and VR development. Let's learn how it works.
What You Will Learn
By the end of this lesson you will be able to: 1. Explain what a 3D model is and name its basic building blocks. 2. Identify the most common 3D model file formats and when to use each one. 3. Find free, usable 3D models from trusted sources online. 4. Describe the steps to import a 3D model into an AR or VR project.
What Is a 3D Model?
A 3D model is a digital object made of three components: VERTICES: Points floating in 3D space, each defined by x, y, and z coordinates. Think of them as dots in the air. EDGES: Straight lines connecting two vertices. FACES (POLYGONS): Flat surfaces enclosed by edges — usually triangles or four-sided squares. The more faces a model has, the more detailed it looks. A game character might use 5,000 to 20,000 polygons. A Hollywood VFX character can have millions. In AR and VR — especially on mobile devices — you usually want FEWER polygons so the scene runs smoothly at 60 frames per second or faster. This style is called low-poly.
The most important file format for web-based AR and VR is GLTF (GL Transmission Format), or its compact binary version GLB. GLTF is sometimes called the JPEG of 3D because it is lightweight and supported nearly everywhere. It bundles geometry, textures, and animations into one fast-loading file.
Common 3D File Formats
OBJ (.obj): One of the oldest 3D formats, dating to the 1980s. Stores only the shape — textures go in a separate file. Good for simple static objects with no animation. FBX (.fbx): Made by Autodesk. Supports animation, bones, and complex materials. Used in major game engines like Unity and Unreal Engine. GLTF or GLB (.gltf or .glb): The modern standard for web and VR. Everything — shape, textures, materials, and animations — packed into one file. Fast to load and the best choice for projects built with A-Frame, Babylon.js, or Three.js. USDZ (.usdz): Apple's format, used for AR Quick Look on iPhone and iPad. If iPhone users need to view your AR scene without downloading any app, USDZ is the format you need.
Match each 3D file format to its best use case.
Terms
Definitions
Drag terms onto their definitions, or click a term then click a definition to match.
Why do AR and VR apps prefer 3D models with fewer polygons?
Where to Find Free 3D Models
You do not have to build every model yourself. Here are trusted free sources: SKETCHFAB (sketchfab.com): The largest 3D model library online. Many models are free under Creative Commons licenses. You can spin and examine each model in 3D right in your browser before downloading. Always check the license — CC BY means you must credit the creator. POLY PIZZA (poly.pizza): Simple low-poly cartoon models, all free to use. Great for fast prototyping and beginner projects. BLENDERKIT (blenderkit.com): High-quality models built in Blender. Some are free, some are paid. When you find a model, always check three things: (1) What is the license? (2) What file format is available? (3) How many polygons does it have?
Before importing a model, look at its polygon count in the file details. For a mobile VR scene, aim to keep ALL objects combined under 50,000 polygons total. One single 500,000-polygon model can freeze the entire experience on a phone.
Hunt for Your VR Scene's First Model
Step 1: Imagine a VR or AR scene you would love to build — a jungle, a space station, an underwater reef, or anything else. Write one sentence describing your scene. Step 2: Go to poly.pizza (free, no account needed). Search for one object your scene needs — such as tiger, asteroid, or coral. Step 3: Click a model you like. Check: (a) What file formats can you download? (b) Does it look good in the preview? (c) What is the creator's name? Step 4: On paper write: your scene description, the model you found, the file format you would download, the credit line you would include, and one sentence explaining why this model fits your scene. Bonus step: If you have a computer, download the GLB version and drag it into the online A-Frame Inspector at aframe.io/docs to see it appear in a live 3D browser scene.
Flashcards — click each card to reveal the answer
What does CC BY mean on a free 3D model from Sketchfab?
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