3D Tiles

specdraftimplproposal

Publish geographic data as 3D Tiles.

Scope

The building block 3D Tiles adds support for 3D Tiles 1.1 for feature collections that can be encoded by ldproxy using the building block Features - glTF.

This building block supports glTF as the tile format and implicit quadtree tiling. Subtrees are encoded using the binary format for compactness.

The only refinement strategy that is supported is ADD. Use the contentFilters configuration option to specify at which level of the tile hierarchy a building will be represented. Each building should be included on exactly one level.

The 3D Tiles can be inspected in a web browser using an integrated Cesium client.

Limitations

See Features - glTF.

In addition, the following information in Subtrees is not supported: property tables, tile metadata, content metadata, and subtree metadata.

Conformance Classes

3D Tiles implements support for the OGC Community Standard 3D Tiles 1.1. glTF is the only supported tile format. All tilesets use implicit quadtree tiling.

Operations

Resource	Path	Methods	Media Types	Description
3D Tiles Tileset	collections/{collectionId}/3dtiles	GET		Access a 3D Tiles 1.1 tileset with implicit quadtree tiling.
3D Tiles Subtree	collections/{collectionId}/3dtiles/subtree_{level}_{x}_{y}	GET		Access a 3D Tiles 1.1 Subtree file.
3D Tiles Content (glTF)	collections/{collectionId}/3dtiles/content_{level}_{x}_{y}	GET		Access a 3D Tiles 1.1 Content file, a glTF 2.0 binary file.

Path Parameters

Name	Resources	Description
collectionId	3D Tiles Tileset, Subtree, Content	The identifier of the feature collection.
level	3D Tiles Subtree, Content	The level of the subtree or tile.
x	3D Tiles Subtree, Content	The column of the subtree or tile.
y	3D Tiles Subtree, Content	The row of the subtree or tile.

Query Parameters

Name	Resources	Description
f	3D Tiles Tileset	Select the output format of the response. If no value is provided, the standard HTTP rules apply, i.e., the "Accept" header will be used to determine the format.

Configuration

Prerequisites

The module requires that the feature provider includes a type building. The requirements for the type are the same as in the configuration of the CityJSON encoding.

Options

Name	Default	Description	Type	Since
buildingBlock		Always TILES3D.	string	v2.0
extensionType		Deprecated See buildingBlock.	string	v2.0
enabled	false	Enable the building block?	boolean	v2.0
firstLevelWithContent	0	The first level of the tileset which will contain buildings. The value will depend on the spatial extent of the dataset, i.e., at what level of the implicit tiling scheme large buildings can be displayed.	number	v3.4
maxLevel	0	The last level of the tileset which will contain buildings. The value will depend on the spatial extent of the dataset, i.e., at what level of the implicit tiling scheme small buildings can be displayed in detail.	number	v3.4
contentFilters	[]	A CQL2 text filter expression for each level between the firstLevelWithContent and the maxLevel to select the buildings to include in the tile on that level. Since the refinement strategy is always ADD, specify disjoint filter expressions, so that each building will be included on exactly one level.	array	v3.4
tileFilters	[ ... ]	A CQL2 text filter expression for each level between the firstLevelWithContent and the maxLevel to select the buildings to include in the tile on that level or in any of the child tiles. This filter expression is the same as all the contentFilters on this or higher levels combined with an OR. This is also the default value. However, depending on the filter expressions, this may lead to inefficient tile filters and to improve performance the tile filters can also be specified explicitly.	array	v3.4
geometricErrorRoot	0	The error, in meters, introduced if a tile at level 0 (root) is rendered and its children at level 1 are not. At runtime, the geometric error is used to compute screen space error (SSE), i.e., the error measured in pixels.	number	v3.4
subtreeLevels	3	The number of levels in each Subtree.	number	v3.4
seeding	{}	Controls how and when tiles are precomputed, see Seeding options in the Tiles building block.	object	v3.4
clampToEllipsoid	false	If set to true, each building will be translated vertically so that the bottom of the building is on the WGS 84 ellipsoid. Use this option, if the data is intended to be rendered without a terrain model.	boolean	v3.4
ionAccessToken	null	If the 3D Tiles should be rendered in the integrated Cesium client using the terrain model from Cesium Ion, specify the access token to use in requests.	string	v3.4
maptilerApiKey	null	If the 3D Tiles should be rendered in the integrated Cesium client using the terrain model from MapTiler, specify the api key to use in requests.	string	v3.4
customTerrainProviderUri	null	If the 3D Tiles should be rendered in the integrated Cesium client using an external Terrain Provider, specify the URI of the provider.	string	v3.4
terrainHeightDifference	0	If the terrain does not match the height values in the data, this option can be used to translate the buildings vertically in the integrated Cesium client.	number	v3.4
style	DEFAULT	A style in the style repository of the collection to be used in maps with 3D Tiles. With DEFAULT the defaultStyle from module HTML is used. With NONE the default 3D Tiles style is used. The style must be available in the 3D Tiles Styling format. If no style is found, 'NONE' is used.	string	v2.0

Examples

- buildingBlock: TILES3D
  enabled: true
  maxLevel: 9
  firstLevelWithContent: 5
  contentFilters:
  - diameter3d(bbox)> 200
  - diameter3d(bbox)<=200 and diameter3d(bbox)> 100
  - diameter3d(bbox)<=100 and diameter3d(bbox)> 40
  - diameter3d(bbox)<=40 and diameter3d(bbox)> 18
  - diameter3d(bbox)<=18
  tileFilters:
  - true
  - diameter3d(bbox)<=200
  - diameter3d(bbox)<=100
  - diameter3d(bbox)<=40
  - diameter3d(bbox)<=18
  geometricErrorRoot: 8192
  clampToEllipsoid: true
  subtreeLevels: 3
  seeding:
    runOnStartup: true
    runPeriodic: false
    purge: false
    maxThreads: 4