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The Chongqing Mountain Chronicle: 21,371 Buildings Growing Against the Horizon

2026-10-12 · ~5 min read · Chongqing · Blender · digital twin · terrain · mountain city

If Beijing’s story is the law of the central axis, Chongqing’s story is the poetry of gravity. The city sits in the folds of parallel ridge-and-valley terrain — buildings cannot float and cannot sink; every foundation’s elevation must be sampled point by point from DEM terrain.

I. The duet of data and terrain

31 MB of OSM data (the 2026-10-11 edition) plus SRTM 30 m elevation, covering Yuzhong, Jiangbei, Nan’an, Shapingba, Jiulongpo, Dadukou, Beibei and other main districts, about 68 km east-west and 72 km north-south. The core district holds 20,948 buildings, 161 with true heights (the tallest being the 458.2 m Luhai International Center), 67,689 roads, and 1,334 water bodies. All 81 DEM tiles downloaded, with elevations basically sound — Chaotianmen at 159 m by the river, Raffles City’s footing at 273 m, matching Chongqing’s terrain character of “foundations chosen on terrace flat dams”; scattered zero-meter and 2,411 m outliers were removed, the terrain data usable as a whole.

One multipolygon unpacking bug patched (dict-ifying tags in the handler), and all 21,410 buildings and 67,689 roads landed in the bag.

II. Buildings growing against the horizon

The core difficulty of the Chongqing model is building base elevation: each building’s base is sampled point by point on the DEM grid so its foundation follows the terrain’s rise and fall — so on the terraced Yuzhong Peninsula, the flat-dam highlands of Shapingba, and the cliffs of Nan’an with hundreds of meters of relief, buildings neither float nor sink. All foundations passed DEM line-of-sight analysis, guaranteed not to be blocked by steep slopes.

Height strategy runs in three tiers: the 161 buildings with true tags are used directly; 1,964 are converted from floor counts; the remaining ~19,000 untagged ones are estimated by “neighboring known-height building spatial interpolation” — the CBD naturally tall, the outskirts naturally low. scipy was installed on the fly and used immediately. The water surface took extra care: the Yangtze and Jialing river faces are vast and cannot share one plane elevation, so a local-minimum-terrain method plus polygon-range double judgment generates the water mesh, with channel width and course consistent with reality.

III. The resurrection of seven landmarks and the cantilever

OSM landmarks are crude boxes, so the Chongqing model hand-rebuilt seven landmarks, replacing the inferior data versions: the Great Hall of the People (modeled on the Temple of Heaven’s Hall of Prayer for Good Harvests, 38 stone columns), the Jiefang Monument (the nation’s only victory memorial stele), the Bell Tower, Hongyadong (stilted-house cluster), the Chongqing Grand Theatre, the Guotai Arts Center, Raffles City (a 250 m aerial cantilever), and the Bai Mansion. The renders show the pattern of two rivers embracing the Yuzhong Peninsula, the Liziba monorail crossing through a building, and the panorama of the Raffles City cluster joined with the waterscape.

Known boundaries are written into the README as well: about 3,800 completely height-less roofs are interpolated estimates and some may deviate from reality; buildings are regular prisms without louvers, platforms, and other facade details; interchanges are simplified, without rebuilding the complete spatial relations of complex multi-level junctions like Heishizi and Panlong.

Real coordinates

Chongqing Blender digital twin terrain mountain city

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