> For the complete documentation index, see [llms.txt](https://mims.oascities.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mims.oascities.org/mims-specification-v9.0/citiverse/mim9-citiverse.md).

# MIM9: Citiverse

This is the page describing OASC's MIM8 on Local Digital Twins (LDTs)

### Description

MIM9 defines the minimal interoperability mechanisms for Virtual Worlds in cities and communities, often called citiverses. It starts where MIM8 stops: MIM8 names "interconnected virtual worlds environments" as the next maturity step but explicitly leaves them out of scope.

**Working definition.** A Virtual World is a persistent, shared and interactive 3D environment of a real or imagined place. It combines 3D, BIM, geospatial and reality-capture content with historical, live and simulated data. People, avatars and AI agents can be present in it at the same time, and it is delivered to browsers, mobile devices and XR headsets over different networks.

A Virtual World can be the immersive front-end of a Local Digital Twin (MIM8). It can also exist without simulation, for example for heritage reconstruction or for preparing a visit to an event venue.

**Why a MIM is needed.** The Citiverse x4 and LDT4SSC Technical Team (start meeting, 30 June 2026) found the same problems across five projects: combining BIM, GIS, city data and sensor data in one scene; the high cost of server-side pixel streaming; dependency on one vendor stack; and no shared definition of a minimum viable citiverse. For citiverses to be affordable for municipalities, services must be interoperable and exchangeable without rebuilding the whole technical stack, so that the citiverse can work as an open marketplace.

| Project         | Pilots                                                                   | Observed stack                                                                                                                 | Interoperability issue                                                                                       | MIM9 capability |
| --------------- | ------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------ | --------------- |
| X-cite          | Tampere (Nokia Arena XR/VR), Rotterdam, Flanders (Mobilize)              | LDT platform as data broker (TML, VITO); API-based data exchange with 3D partners                                              | Proving interoperability across separate use cases and with the LDT4SSC toolbox                              | C1, C2          |
| CU (AccessCity) | Gothenburg Horse Show arena                                              | BIM, GIS, Revit CAD, city data, sensor and CCTV metadata; OpenUSD structure; Unreal Engine pixel streaming; AI avatars; Cesium | Cost of high-fidelity worlds and server-side streaming at scale                                              | C1, C3, C5      |
| SENSE           | Cartagena (mobility, planning), Kiel (historical reconstruction, marine) | Federated data space; Eclipse SUMO; Unreal Engine pixel streaming; Google 3D data, drone scans planned                         | Moving from server-side to client-side rendering for public use; no definition of a minimum viable citiverse | C4, C5          |
| 3DxVerse        | Hamburg, Aruba                                                           | Emission modelling with ISO 14083 and ISO 23795; smartphone and CAN-bus trip data                                              | Linking object-level emission data to the 3D world                                                           | C2              |
| LDT4SSC         | Blueprint for other projects                                             | Dual stack: commercial sandbox plus open source (Cesium); OGC Records, Processes and Features                                  | Reuse of the blueprint by other projects and pilots                                                          | C1, C6          |


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