3D Tiles
This page covers how to integrate 3D Tiles into your metadata through namespaces.
About 3D Tiles
3D Tiles is an open standard for streaming massive heterogeneous 3D geospatial datasets. Developed by Cesium and adopted as an Open Geospatial Consortium (OGC) Community Standard, 3D Tiles defines a spatial data structure and a set of tile formats designed to efficiently stream and render massive 3D geospatial content such as terrain, buildings, photogrammetry, and point clouds.
3D Tiles enables streaming and rendering of large-scale 3D geospatial data across devices and platforms by implementing a hierarchical level of detail structure that allows clients to request only the necessary data based on the current view position, orientation, and zoom level.
Core 3D Tiles Concepts
Key concepts in 3D Tiles that are relevant to metadata integration:
- Tileset: Hierarchical structure of tiles with level-of-detail capability
- Tile Formats: Specific formats for different content types (b3dm, i3dm, pnts, cmpt)
- Bounding Volumes: Spatial boundaries for efficient culling and selection
- Refinement: Replacement or additive strategies for level of detail
- Metadata: Asset, feature, and content property information
- Styling: Runtime styling capabilities based on feature properties
- Batched Content: Multiple objects grouped together for efficient rendering
- Instanced Content: Repeated elements like trees, furniture, etc.
Implementing the 3D Tiles Standard
Namespace Declaration
{
"@context": {
"@vocab": "https://schema.org/",
"mvmd": "https://mvmd.org/v1/",
"3dtiles": "https://www.ogc.org/standards/3DTiles/schemas/"
}
}
Linking Example
When referencing external 3D Tiles assets:
{
"@context": {
"@vocab": "https://schema.org/"
},
"@type": "Dataset",
"name": "City Buildings Tileset",
"contentUrl": "https://example.com/tilesets/city/tileset.json",
"encodingFormat": "application/json;type=3dtiles"
}
With version and detailed information:
{
"@context": {
"@vocab": "https://schema.org/"
},
"@type": "Dataset",
"name": "City Buildings Tileset",
"contentUrl": "https://example.com/tilesets/city/tileset.json",
"encodingFormat": "application/json;type=3dtiles",
"version": "1.1",
"spatialCoverage": {
"@type": "GeoShape",
"box": "40.730610,-73.935242 40.753182,-73.981903"
},
"contentSize": "2.5 GB",
"dateCreated": "2023-05-15"
}
Embedding Example
When embedding 3D Tiles metadata directly:
{
"@context": {
"@vocab": "https://schema.org/",
"3dtiles": "https://www.ogc.org/standards/3DTiles/schemas/"
},
"@type": "Dataset",
"name": "City Buildings Tileset",
"3dtiles:version": "1.1",
"3dtiles:asset": {
"version": "1.1",
"tilesetVersion": "2.0",
"gltfUpAxis": "Z"
},
"3dtiles:geometricError": 500,
"3dtiles:root": {
"boundingVolume": {
"region": [
-1.3197209591796106,
0.6988424910858092,
-1.3196390408203893,
0.6989055089141921,
0,
500
]
},
"geometricError": 100,
"refine": "ADD",
"children": 8
},
"3dtiles:properties": {
"maximum": {
"height": 300,
"area": 15000,
"buildingYear": 2023
},
"minimum": {
"height": 1,
"area": 10,
"buildingYear": 1850
}
},
"3dtiles:contentTypes": ["b3dm", "pnts", "i3dm"],
"3dtiles:statistics": {
"tileCount": 5428,
"pointCount": 50000000,
"featureCount": 25000,
"maxDepth": 20
}
}
Common Use Cases
3D Tiles is used in a variety of geospatial applications:
- Smart city visualization
- Urban planning and analysis
- Digital twin creation for cities and infrastructure
- Real estate development visualization
- Infrastructure asset management
- Environmental monitoring and analysis
- Cultural heritage preservation
- Disaster response planning
- Transportation planning and simulation
- Augmented reality for geospatial contexts
Implementation Examples
Basic Example
A simple 3D Tiles tileset reference:
{
"@context": {
"@vocab": "https://schema.org/"
},
"@type": "Dataset",
"name": "Downtown Buildings 3D Model",
"description": "3D Tiles dataset of downtown buildings with height and construction year attributes",
"contentUrl": "https://example.com/tilesets/downtown/tileset.json",
"encodingFormat": "application/json;type=3dtiles",
"license": "https://creativecommons.org/licenses/by/4.0/",
"dateCreated": "2023-03-12"
}
Complete Example
For a complete 3D Tiles dataset with detailed metadata:
{
"@context": {
"@vocab": "https://schema.org/",
"3dtiles": "https://www.ogc.org/standards/3DTiles/schemas/"
},
"@type": "Dataset",
"name": "Metropolitan Area Digital Twin",
"description": "Comprehensive 3D tileset of the metropolitan area including buildings, terrain, vegetation, and infrastructure",
"contentUrl": "https://example.com/tilesets/metro-area/tileset.json",
"encodingFormat": "application/json;type=3dtiles",
"creator": {
"@type": "Organization",
"name": "Geospatial Digital Twin Consortium",
"url": "https://geospatial-dtc.example.org"
},
"license": "https://creativecommons.org/licenses/by-nc/4.0/",
"dateCreated": "2023-02-18",
"dateModified": "2023-08-05",
"spatialCoverage": {
"@type": "GeoShape",
"box": "34.0522,-118.2437 34.1522,-118.1437"
},
"contentSize": "4.8 GB",
"3dtiles:version": "1.1",
"3dtiles:asset": {
"version": "1.1",
"tilesetVersion": "2.3",
"gltfUpAxis": "Z"
},
"3dtiles:schema": {
"classes": {
"building": {
"properties": {
"height": {"type": "FLOAT64"},
"area": {"type": "FLOAT64"},
"buildingType": {"type": "STRING"},
"constructionYear": {"type": "INT32"},
"energyRating": {"type": "STRING"},
"occupancy": {"type": "STRING"},
"hasUnderground": {"type": "BOOLEAN"}
}
},
"vegetation": {
"properties": {
"height": {"type": "FLOAT32"},
"species": {"type": "STRING"},
"crownDiameter": {"type": "FLOAT32"},
"age": {"type": "INT16"}
}
},
"road": {
"properties": {
"type": {"type": "STRING"},
"width": {"type": "FLOAT32"},
"material": {"type": "STRING"},
"lanes": {"type": "INT8"}
}
}
}
},
"3dtiles:metadata": {
"tilesetSource": "Combined photogrammetry, LiDAR, and GIS data",
"captureDate": "2022-11-15 to 2023-01-20",
"processingSoftware": "Geospatial Processing Suite 4.5",
"coordinateSystem": "EPSG:4326",
"verticalDatum": "NAVD88",
"positionalAccuracy": "0.15m horizontal, 0.25m vertical",
"tilesetContact": "support@geospatial-dtc.example.org"
},
"3dtiles:layers": [
{
"name": "buildings",
"description": "3D buildings with attributes",
"contentType": "b3dm",
"featureCount": 25430,
"attributes": ["height", "buildingType", "constructionYear"]
},
{
"name": "terrain",
"description": "Detailed terrain mesh",
"contentType": "cmpt",
"resolution": "0.5m"
},
{
"name": "vegetation",
"description": "Trees and other vegetation",
"contentType": "i3dm",
"featureCount": 156280,
"attributes": ["height", "species"]
},
{
"name": "pointclouds",
"description": "LiDAR point clouds for select areas",
"contentType": "pnts",
"pointCount": 78500000,
"pointSpacing": "0.1m"
}
],
"3dtiles:extensions": [
"3DTILES_implicit_tiling",
"3DTILES_metadata",
"3DTILES_content_gltf"
],
"3dtiles:statistics": {
"tileCount": 18254,
"maxDepth": 22,
"totalByteSize": 4.8e9,
"maximumTriangleCount": 12000000,
"maximumPointCount": 78500000
},
"3dtiles:optimizationFeatures": {
"preloadAncestors": true,
"unloadSkippedLevels": true,
"skipLevelOfDetail": true,
"maximumScreenSpaceError": 16
}
}
Smart City Example
Example for smart city application with analytics properties:
{
"@context": {
"@vocab": "https://schema.org/",
"mvmd": "https://mvmd.org/v1/",
"3dtiles": "https://www.ogc.org/standards/3DTiles/schemas/"
},
"@type": "Dataset",
"name": "Smart City Dashboard 3D Assets",
"description": "Interactive 3D representation of city assets with real-time sensor data integration",
"contentUrl": "https://smartcity.example.org/tilesets/dashboard/tileset.json",
"encodingFormat": "application/json;type=3dtiles",
"creator": {
"@type": "Organization",
"name": "Smart City Initiative",
"url": "https://smartcity.example.org"
},
"license": "https://creativecommons.org/licenses/by-sa/4.0/",
"dateCreated": "2023-05-28",
"additionalProperty": [
{
"@type": "PropertyValue",
"propertyID": "analyticsIntegration",
"name": "Analytics Integration",
"value": {
"dataIntegrationAPI": "https://smartcity.example.org/api/v2/",
"realTimeDataSources": [
{
"name": "trafficSensors",
"updateFrequency": "30s",
"coverage": "major roads and intersections",
"visualizationType": "color coding and flow lines"
},
{
"name": "airQualitySensors",
"updateFrequency": "5min",
"coverage": "citywide grid at 500m intervals",
"visualizationType": "heat map overlay"
},
{
"name": "energyConsumption",
"updateFrequency": "15min",
"coverage": "all municipal buildings and 60% of commercial buildings",
"visualizationType": "building color and glow effects"
},
{
"name": "pedestrianActivity",
"updateFrequency": "5min",
"coverage": "downtown and commercial districts",
"visualizationType": "dynamic dot density"
}
],
"historicalDataAccess": "https://smartcity.example.org/api/v2/historical/",
"predictionModels": [
"traffic flow prediction",
"energy demand forecasting",
"air quality prediction"
]
}
}
],
"3dtiles:version": "1.1",
"3dtiles:asset": {
"version": "1.1",
"tilesetVersion": "3.2",
"gltfUpAxis": "Z"
},
"3dtiles:extensions": [
"3DTILES_metadata",
"3DTILES_implicit_tiling",
"3DTILES_time_dynamic_points"
],
"3dtiles:styling": {
"styles": [
{
"name": "default",
"description": "Standard city visualization"
},
{
"name": "trafficAnalysis",
"description": "Road network colored by traffic volume"
},
{
"name": "energyEfficiency",
"description": "Buildings colored by energy consumption"
},
{
"name": "airQuality",
"description": "Air quality overlay on city model"
},
{
"name": "solarPotential",
"description": "Building rooftops colored by solar energy potential"
}
]
}
}
JSON Schema Validation
For validating 3D Tiles namespace references in MVMD, the following schema properties are defined:
{
"$schema": "http://json-schema.org/draft-07/schema#",
"title": "3D Tiles Namespace Schema",
"type": "object",
"properties": {
"3dtiles:version": {
"type": "string",
"description": "3D Tiles specification version"
},
"3dtiles:asset": {
"type": "object",
"description": "Asset information about the tileset",
"properties": {
"version": { "type": "string" },
"tilesetVersion": { "type": "string" },
"gltfUpAxis": {
"type": "string",
"enum": ["X", "Y", "Z"]
}
}
},
"3dtiles:geometricError": {
"type": "number",
"description": "The error, in meters, introduced if this tileset is not rendered"
},
"3dtiles:root": {
"type": "object",
"description": "Information about the root tile"
},
"3dtiles:properties": {
"type": "object",
"description": "Object containing property values for the tileset"
},
"3dtiles:contentTypes": {
"type": "array",
"description": "Tile content types used in the tileset",
"items": {
"type": "string",
"enum": ["b3dm", "i3dm", "pnts", "cmpt", "gltf", "glb"]
}
},
"3dtiles:schema": {
"type": "object",
"description": "Schema for feature metadata in the tileset"
},
"3dtiles:metadata": {
"type": "object",
"description": "Additional metadata about the tileset"
},
"3dtiles:layers": {
"type": "array",
"description": "Layers or feature types in the tileset",
"items": {
"type": "object",
"properties": {
"name": { "type": "string" },
"description": { "type": "string" },
"contentType": { "type": "string" }
},
"required": ["name"]
}
},
"3dtiles:extensions": {
"type": "array",
"description": "3D Tiles extensions used in the tileset",
"items": { "type": "string" }
},
"3dtiles:statistics": {
"type": "object",
"description": "Statistical information about the tileset"
},
"3dtiles:optimizationFeatures": {
"type": "object",
"description": "Optional features for client-side optimization"
},
"3dtiles:styling": {
"type": "object",
"description": "Styling options for the tileset"
}
}
}
JSON-LD Context
The 3D Tiles namespace can be mapped to JSON-LD context for semantic interoperability:
{
"@context": {
"3dtiles": "https://www.ogc.org/standards/3DTiles/schemas/",
"3dtiles:version": { "@id": "3dtiles:version" },
"3dtiles:asset": { "@id": "3dtiles:asset" },
"3dtiles:geometricError": { "@id": "3dtiles:geometricError" },
"3dtiles:root": { "@id": "3dtiles:root" },
"3dtiles:properties": { "@id": "3dtiles:properties" },
"3dtiles:contentTypes": { "@id": "3dtiles:contentTypes" },
"3dtiles:schema": { "@id": "3dtiles:schema" },
"3dtiles:metadata": { "@id": "3dtiles:metadata" },
"3dtiles:layers": { "@id": "3dtiles:layers" },
"3dtiles:extensions": { "@id": "3dtiles:extensions" },
"3dtiles:statistics": { "@id": "3dtiles:statistics" },
"3dtiles:optimizationFeatures": { "@id": "3dtiles:optimizationFeatures" },
"3dtiles:styling": { "@id": "3dtiles:styling" }
}
}
Implementation Considerations
When implementing the 3D Tiles namespace, keep these considerations in mind:
- Client Support: Ensure target client applications support the 3D Tiles version used
- Streaming Performance: Balance tile size and detail for optimal streaming performance
- Level of Detail: Configure appropriate geometric error values for view-dependent LOD
- Feature Metadata: Design a clear schema for searchable and filterable feature attributes
- Extensions: Document any extensions used to ensure client compatibility
- Styling: Consider runtime styling needs when structuring the tileset
- Coordinate Systems: Be explicit about the coordinate system and vertical datum
- Data Size: Implement appropriate optimizations for large datasets
- Integration: Plan for integration with other data sources like real-time sensors