Proposal:3D model repository links

3D Model Repository links
Proposal status:	Inactive (inactive)
Proposed by:	Tordanik
Tagging:	3dmr=* Data item
Applies to:	, , ,
Definition:	Link to an externally hosted 3D model
Statistics:
Rendered as:	Visible in 3D renderers
Draft started:	2017-06-19

Using the new key 3dmr=*, it will be possible to link to a 3D model from the 3D Model Repository.

Rationale

The 3D Model Repository is a free and open collection of 3D models, under licenses compatible with OSM data. These can be used by 3D renderers to go beyond what's possible Simple 3D Buildings and similar tagging schemes, while still relying on OSM data for the rest of the scene.

Unlike the OSM database, IDs in the 3D Model Repository are relatively stable, and lend themselves well to linking. At the time of writing, each ID represents exactly one model, but it may eventually represent a set of models of the same real-world feature (e.g. for different levels of detail).

This proposal only covers basic links. More advanced features may be introduced in the future.

For the most part, this tag is equivalent to building:obm=*, which was in use with OpenBuildingModels (a defunct spiritual predecessor of the 3D Model Repository). However, it is not limited to buildings.

Proposed tagging

The suggested tag is 3dmr=<id>, where id is the ID of the model in the 3D Model Repository.

A 3D renderer supporting this tag may then ...

• obtain the model from the 3D Model Repository and place it in that location, and
• ignore the tagged OSM elements for 3D rendering, to avoid duplication.

Additional tags

At least the following existing keys are taken into account to scale and rotate a generic model:

• direction=* with cardinal directions or angles as the value
• height=*
• width=*
• length=*

Other tags and conventions (e.g. deriving a bollard's rotation from the way containing it, ...) should also be taken into account.

Tagable features

The tag applies to all elements – nodes, ways, areas, and relations. When applied to a relation (e.g. a bridge relation or parking relation) or outline (e.g. a building=*) area), features that semantically belong to these "root" elements should also be replaced with the model.

Creating new elements for the sole purpose of linking a model from the 3D Model Repository should be avoided wherever possible. Usually, this is a sign that the linked model does not have the intended granularity: Instead of creating a single model containing both a castle and the decorative fountains in front of it, for example, the model should be subdivided into separate models for the building and fountains. These can then be easily linked to existing OSM elements.

Examples

Photo	Tagging	Interpretation
	node or area, tagged amenity=fountain 3dmr=42	Link to an external model for an historic fountain. This id will only appear in the database once, as the fountain is unique.
	4 nodes, each tagged amenity=bench 3dmr=42 direction=* The direction key defines the facing of the bench, as usual.	Link to a model for the bench design. There will be four instances of the same model. Example
	area, tagged building=* 3dmr=42	Link to a model of the building. Like the fountain example, but also replaces any building:part=* elements and indoor features of this building. Example
	area, tagged man_made=bridge 3dmr=42	Link to a model of the bridge. Implicitly includes the road(s) and other features on top of the bridge, as well as bridge:support=* and other related elements.

External discussions

• Diary with posts about the repository's development

Comments

Please comment on the discussion page.