Enabling people to use 3DMR without necessarily also having to use OSM data is interesting. And I wouldn’t mind having Wikidata IDs as an optional property for 3DMR models, alongside a suitable API for querying them.
However, using indirect links through Wikidata as a replacement for direct 3dmr links has some drawbacks. Most of them are somewhat at odds with a desire to keep things simple:
- Extra complexity: We would still need 3dmr tags for objects which aren’t unique, or for unique objects which don’t have a Wikidata item. Having only one possible mechanism for linking 3dmr models is simpler than having two. Especially if the second one involves understanding and possibly registering with a third project.
- Unexpected consequences: It’s surprising that changing wikidata tagging might alter or break 3D maps.
- Mismatched definitions: It’s not always clear what belongs to a particular entity. (Does the road leading through the gate belong to the gate? Does the statue include the pedestal?) Wikidata and OSM may not always give the same answer to those questions.
- Editing conflicts: How do we prevent/resolve a situation where more than one model on 3DMR points to the same Wikidata item? If this decision is encapsulated in an OSM 3dmr tag, we can use OSM’s existing history tracking and conflict resolution mechanisms.
I do appreciate the goal of not having to maintain an additional external link in OSM. But even in the best case, we’d only move that additional link somewhere else: Instead of an OSM→WD link and an OSM→3DMR link, you would now have an OSM→WD link and a 3DMR→WD link. And that’s only if people actually omit 3dmr tags if wikidata is present, which is not what happens with wikipedia tags.