Technical Showcase
Campus 3D Mapping
From Nadir Imagery to Attributed City Model
Reality Capture · ITB Campus · Metashape SfM + LangSAMStructure-from-motion at 2 cm per pixel. Language-guided segmentation assigns every building and tree a footprint, a height, and an area, without a single manual digitizing session.
A campus at 2 cm per pixel
Hundreds of overlapping UAV frames pass through Metashape's structure-from-motion pipeline, producing a seamless orthophoto at 2 cm ground sampling distance, sharp enough to read surface markings and resolve individual roof panels from above.
77 objects, labeled without hand-digitizing
LangSAM (Language-Segment-Anything-Model) detects building and tree footprints directly from the orthophoto using language prompts, with no manual polygon drawing. Each feature inherits height from the CHM. The tallest campus building reaches 29 m; most tree canopies cluster below 10 m. Hover any feature to inspect its class, height, and footprint area.
Volume, form, and texture
The Metashape MVS mesh captures volumetric form across the campus block. Roof texture is photo-accurate at 8K resolution; wall surfaces exhibit interpolation artifacts inherent to nadir-only acquisition, acknowledged rather than hidden. This is the foundation of a campus digital twin workflow.
Methodology & data notes
UAV nadir imagery (≈2 cm GSD) processed in Agisoft Metashape: sparse reconstruction → dense point cloud → DEM + orthomosaic. Building and tree footprints detected without manual digitizing using LangSAM (Language-Segment-Anything-Model), prompted on the orthophoto. Each polygon attributed with mean/max height from the Canopy Height Model (DSM − DTM). 3D mesh (GLB) from Metashape build-texture pipeline (Generic mapping, Mosaic blending, 8K atlas). Known limitations: wall textures show interpolation artifacts inherent to nadir-only acquisition; mesh uses Metashape local coordinates, not GPS-registered lon/lat.
| GSD | ≈ 2 cm / pixel |
|---|---|
| Detection model | LangSAM (Language-Segment-Anything) |
| Objects detected | 77 (buildings + trees) |
| Max building height | 29.15 m |
| Mesh texture | 8K atlas · Mosaic blending |
| Limitation | Wall interpolation (nadir-only acquisition) |
| Coordinates | Ortho + GeoJSON: WGS84 · Mesh: Metashape local |