**Note** from Bead: Business Model And Strategy · [canonical source](https://redfish.acequia.io/guerin/.agents/fa3b0dc9-9dc9-479d-b40a-d6d5400ae313/2026-06-11/notes/03-gcj-02-requirement.md) · session 2026-06-11 · discussion: Talk: Business Model And Strategy
Working note expanding the geodata wall flagged in [02-china-minimum-requirements.md](https://redfish.acequia.io/guerin/.agents/fa3b0dc9-9dc9-479d-b40a-d6d5400ae313/2026-06-11/notes/02-china-minimum-requirements.md). Research-grade, not legal advice.
## What GCJ-02 is - **GCJ-02** (国测局 / State Bureau of Surveying and Mapping, 2002 — colloquially "Mars coordinates") is the coordinate datum **required for all published maps of mainland China**. It applies a deliberate, **nonlinear, position-dependent offset** to WGS-84 — roughly 50–700 m, varying by location, so it cannot be corrected by a constant shift. - **BD-09** is Baidu's additional transform layered on top of GCJ-02 (Baidu tiles only). - Legal frame: the Surveying & Mapping Law + 2016 Map Management Regulations. Internet-map data must be stored on servers **inside China**; **datum conversion (WGS-84 ↔ GCJ-02) is itself a licensed surveying activity** — only a small set of licensed Chinese firms may lawfully perform it; foreign providers cannot hold internet-map qualifications. Penalties to RMB 500k + criminal exposure for serious cases. - Hong Kong and Macau are **outside** the GCJ-02 requirement (WGS-84 is fine there). Incumbent practice: Google serves GCJ-02 tiles for China; Apple Maps in China runs on AutoNavi (Amap); state-run **Tianditu (天地图)** is the official basemap service.
## Why it bites us specifically Simtable and realtime.earth composite **WGS-84 overlays** (GPS tracks, sensor/camera positions, GeoJSON layers, fire perimeters) onto basemaps. On a GCJ-02 basemap, untransformed WGS-84 overlays land **hundreds of meters off** — for emergency-management use that is a safety-relevant error, not a cosmetic one. Conversely, applying the transform ourselves is the legally restricted act when done in-country. Open-source approximations of the transform exist (`eviltransform` and kin) and are accurate to a few meters. Offshore use for display alignment is common industry practice; in-country use sits in a legal gray zone because conversion is a licensed activity. That asymmetry (offshore gray-OK / onshore restricted) should drive the architecture.
## Practical postures 1. **Offshore Tier 0–1 (current):** render customer-own or global data on global basemaps; do not ingest, store, or republish China-territory geodata; no GCJ-02 work needed. 2. **Serving Chinese users a China map view:** use licensed-partner tiles (Amap / Tianditu / Baidu) which are already GCJ-02; overlay alignment then requires the transform — counsel question on where (client-side offshore?) that may lawfully run. 3. **Onshore (Tier 2+):** licensed Chinese map partner mandatory; map data on China servers; partner performs/blesses datum handling. Pairs with the reseller / license-model decision.
## See also - Full report §4 and §7: [china-market-entry-report.md](https://redfish.acequia.io/guerin/.agents/fa3b0dc9-9dc9-479d-b40a-d6d5400ae313/2026-06-11/artifacts/china-market-entry-report.md) - [Restrictions on geographic data in China (Wikipedia)](https://en.wikipedia.org/wiki/Restrictions_on_geographic_data_in_China) - [Lexology — Navigating China's Digital Map Regulations](https://www.lexology.com/library/detail.aspx?g=9f755dba-12a6-47b5-8b47-c16200cb6d58) - [Intellias — Map compilation for China](https://intellias.com/map-compilation-for-china-challenges-and-ways-to-overcome-them/)
## References (bead cross-links) - Bead 9f755dba · [canonical](https://redfish.acequia.io/guerin/.agents/9f755dba-12a6-47b5-8b47-c16200cb6d58/) (no page yet)