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Meta XR Simulator Room JSON Syntax

Updated: Sep 3, 2026

Overview

Meta XR Simulator has two built-in rooms in JSON format. The JSON files for these rooms are located in the config/anchors directory, in your Meta XR Simulator package.

Default file: scene_anchors_empty_room.json

Other file: scene_anchors_room_with_furnitures.json

You can create a new scene JSON file in two ways.

Generate a new scene JSON file using SceneDataRecorder.apk. For more information, see Scene Data Recorder.

Copy one of the existing JSON files and edit it. The rest of this section describes the layout of the document and what to update. You can give your new JSON file any name. Load the file with the bundled JSON Synthetic Environment Server as described in Meta XR Simulator JSON Format Rooms.

The simulator loads two room formats, and the two routes above produce different ones.

The bundled rooms in config/anchors use the anchors and components layout. This page documents that layout.

Scene Data Recorder writes scene_recorder_out.json, which starts with "type": "scene_META". That is a different layout, and the field names below do not apply to it.

Both load, so either works as a room. If you want to hand-edit using this page, start from a bundled room rather than from a recording.

Scene JSON positions and dimensions use meters, independent of the application engine's display units. For example, increasing a ceiling position by 1 moves it by one meter.

Layout

The layout of the JSON file is separated into two sections, Anchors and Components.

The Anchors section lists the UUID of every anchor in the scene. The Components section lists details on each component belonging to each scene anchor. A component specifies an element of an anchor.

Components

Bounded2D

Locatable

RoomLayout

SemanticLabels

SpaceContainer

With this file, you can add/edit furniture, or change the layout of the scene.

Frequent tasks

Adding furniture

Add a Desk in the center of the room. In the noted sections, add the following elements to each list. You will notice the same UUID is consistent throughout the file for this new furniture item. This UUID must be unique and a character set in a similar format to the other UUIDs you see in the file.

Add an item to the SemanticLabels list. The label is specified as TABLE.

 {
                 "anchor": "3f2a91c4-7b18-4e52-9a63-c0d5e8f71a24",
                 "enabled": true,
                 "labels": [
                     "TABLE"
                 ]
             }

Labels have different images associated with them. The format accepts these labels:

BED

CEILING

CHAIR

COUCH

DOOR_FRAME

FLOOR

GLOBAL_MESH

INNER_WALL_FACE

INVISIBLE_WALL_FACE

LAMP

OPENING

OTHER

OTHER_ROOM_FACE

PLANT

SCREEN

STORAGE

TABLE

WALL_ART

WALL_FACE

WINDOW_FRAME

An entity with an empty labels array carries no semantic label.

Add to the Bounded2D list. This is where you specify the dimensions of the object.

 {
                 "anchor": "3f2a91c4-7b18-4e52-9a63-c0d5e8f71a24",
                 "enabled": true,
                 "rect2D": {
                     "extent": {
                         "height": 1.149999976158142,
                         "width": 0.6000000238418579
                     },
                     "offset": {
                         "x": -0.30000001192092896,
                         "y": -0.5699999928474426
                     }
                 }
             }

Add to the Locatable list. This is where you specify the orientation and position of the object.

 {
                 "anchor": "3f2a91c4-7b18-4e52-9a63-c0d5e8f71a24",
                 "enabled": false,
                 "pose": {
                     "orientation": {
                         "w": -0.06019899994134903,
                         "x": 0.06019800156354904,
                         "y": 0.7045429944992065,
                         "z": 0.7045369744300842
                     },
                     "position": {
                         "x": -0.66,
                         "y": -0.2223919928073883,
                         "z": 0.4180830121040344
                     }
                 }
             }

Note: It is enabled false here but set to true automatically during runtime. This requires no action from the user.

The UUID 3f2a91c4-7b18-4e52-9a63-c0d5e8f71a24 created here now needs to be added to two additional sections.

SpaceContainer: spaces list.

"SpaceContainer": [
            {
                "anchor": "a06dd9cc-b1a1-41be-88b7-d3f6d9060b7b",
                "enabled": true,
                "spaces": [
                    "8e35c573-3f10-4e86-8bdd-69494291b45c",
                    "cb604449-6eb0-43cb-b3a4-9dfc49a35936",
                    "cb604449-6eb0-43cb-b3a4-9dfc49a35936",
                    "01a0341a-4d37-4804-9ace-baa126807f6d",
                    "4f351907-1acc-46b2-87e8-a7acb346879c",
                    "69f388a6-3f1b-428e-bc59-6151321efd11",
                    "ded852e9-f81a-4a6a-a8b6-1e2f3b6929cb",
                    "2e26c462-f4c8-4cf7-b258-a8ae195f75f3",
                    "aec8e50d-8f63-4769-9518-683a9435b452",
                    "3f2a91c4-7b18-4e52-9a63-c0d5e8f71a24"
                ]
            }
        ]

Anchors: list at the top of the file.

"anchors": [
        "01a0341a-4d37-4804-9ace-baa126807f6d",
        "2e26c462-f4c8-4cf7-b258-a8ae195f75f3",
        "4f351907-1acc-46b2-87e8-a7acb346879c",
        "69f388a6-3f1b-428e-bc59-6151321efd11",
        "8e35c573-3f10-4e86-8bdd-69494291b45c",
        "a06dd9cc-b1a1-41be-88b7-d3f6d9060b7b",
        "aec8e50d-8f63-4769-9518-683a9435b452",
        "cb604449-6eb0-43cb-b3a4-9dfc49a35936",
        "ded852e9-f81a-4a6a-a8b6-1e2f3b6929cb",
        "3f2a91c4-7b18-4e52-9a63-c0d5e8f71a24"
    ],

Save and run your project with Meta XR Simulator as before. A new table appears in your scene.

A new table in the scene after saving and re-running the project.

Change layout of walls

Adding or editing a wall follows the same pattern. Start from an existing wall.

To alter a wall, first identify its UUID. Find the RoomLayout component and read its walls list.

"RoomLayout": [
            {
                "anchor": "a06dd9cc-b1a1-41be-88b7-d3f6d9060b7b",
                "ceiling": "ded852e9-f81a-4a6a-a8b6-1e2f3b6929cb",
                "enabled": true,
                "floor": "69f388a6-3f1b-428e-bc59-6151321efd11",
                "walls": [
                    "8e35c573-3f10-4e86-8bdd-69494291b45c",
                    "cb604449-6eb0-43cb-b3a4-9dfc49a35936",
                    "01a0341a-4d37-4804-9ace-baa126807f6d",
                    "4f351907-1acc-46b2-87e8-a7acb346879c"
                ]
            }
        ],

Use the first wall UUID as an example: 8e35c573-3f10-4e86-8bdd-69494291b45c.

Changing the position of the wall

Find the entry in the Locatable list whose anchor matches that UUID.

Increase the pose:position:z by 2.

Old value for z: 2.18451189994812

New value for z: 4.18451189994812

The wall will now appear like this:

Illustrating how the wall's position has changed after increasing pose:position:z.

Changing the height of the wall

Find the entry in the Bounded2D list whose anchor matches that UUID.

Increase the rect2D:extent:height by 4.

Old value for height: 2.690000057220459

New value for height: 6.690000057220459

Illustrating how the wall's height has changed after increasing rect2D:extent:height.

Increasing the height expands the wall in both directions. To keep the wall aligned with the floor, change its Y position as well, as the next section shows.

Set the ceiling height

To raise the ceiling height, use the default scene JSON file scene_anchors_empty_room.json as an example. Note the original appearance of this room.