# London Field Atlas — Rhino mass workflow

1. Open City models and download the required region ZIP(s), or download one building's .3dm from its card. The expanded city has 37 regional files: eight central regions plus outer context patches. They share the same city origin. Import the required regional files into one Rhino document.
2. Open in Rhino 6 or 7 (also supported by Rhino 8). Downloads are saved in Rhino 6 file format. Files use metres, X east, Y north, Z up. City origin is latitude 51.51, longitude -0.106 (WGS84 local azimuthal equidistant projection).
3. Keep the origin, orientation and scale. Individual building files use a local origin at that building's anchor; the website applies that anchor automatically. Do not move a city model to a building-local origin or vice versa.
4. Models are editable meshes, not parametric NURBS/BIM. Use mesh editing tools or replace with your own geometry. For new NURBS, run Mesh and save the resulting visible mesh objects. Avoid duplicate visible surfaces and meshes.
5. Save as .3dm. In the website choose Import Rhino, choose the matching target and file, check the displayed dimensions, then Apply to map.
6. For whole-city files preserve object names LM:<building-id>|<object-id> to preserve building selection. Other names become context. IDs: stpauls, shard, gherkin, towerbridge, tate, millennium, barbican, lloyds, westminster, abbey, museum, tower, isokon, battersea, peckham, laban, canadasquare, crossrail, navalcollege, queenshouse, observatory. Applying a regional file to the whole-city target replaces the displayed city with that region. Merge all wanted regions first. A merged full city is about 403 MB before mesh reduction, so use ReduceMesh or work on one landmark to fit the 100 MB browser limit.
7. Files remain in this browser's IndexedDB only. Clearing browser data removes them. Keep your own .3dm backup. Original restore affects the selected target only.

One unit = 1 metre. Automatic metre/mm/cm/feet/inch units are supported. Override if necessary. Models are not normalized or automatically resized. Maximum upload: 100 MB and 3 million triangles, extent 25 km.

Data: © OpenStreetMap contributors, https://www.openstreetmap.org/copyright, ODbL 1.0. Central snapshot 2026-09-21, north/west extension 2026-09-30 plus Geofabrik east/south snapshot 2026-09-29. 224,658 model parts: continuous central coverage plus local outer patches across a 34.63 x 32.17 km extent. Footprints and coordinates are geographic data; height values include 5,272 recorded heights, 84,480 storey estimates and 134,906 assumed or reference-informed parts. 100 landmark groups have source-informed form corrections in this review; these are approximate architectural studies, not survey reconstructions. Each corrected model includes its references and limitations in the object attributes. Isokon retains its mapped position and orientation, with 94 editable parts; its 14.25 m height and detail dimensions remain approximate. 275 of 289 stops have individual Rhino 6 files; 14 remain location markers. Terrain is flat. The complete editable dataset is assets/city-data.zip. The streaming index assets/city.json references a separate losslessly compressed landmark-meshes.json.gz payload and packed context meshes; raw context tile JSON is retained in tools/city-tiles in the source repository. Browser and Rhino use the same full-resolution source geometry.

New landmark roof/section profiles are approximate where stated on their cards. The 37 regional files contain disjoint sets of objects at the shared origin; merging them does not duplicate buildings. Surroundings and streets alone contain 4.75 million triangles, so a complete merged import needs reduction. Use one landmark or region at a time. See catalog-notes.md for the current quality review.