A 3D model that looks complete is not automatically a reliable model. Recently a client sent us an existing 3D model of a multi-storey building together with the point cloud it was supposedly based on. The model had not been created by VMTS. Before taking over the project, our team did what we do with every incoming dataset: we overlaid the model with the point cloud and compared them section by section.<\/p>\n\n\n\n
The result: 14 documented deviations, 8 of them critical, with height differences of up to approx. 36 cm and a floor slab modelled inside an elevator shaft. This article shows what we found, why errors like these are expensive, and how you can check a BIM model against the point cloud before you build on it.<\/p>\n\n\n\n
In short<\/p>\n
A model-to-point-cloud check overlays the BIM model with the scan data and measures where geometry and reality differ.<\/p>\n<\/li>\n
In this case we documented 14 deviations in a spot check, 8 of them critical.<\/p>\n<\/li>\n
Measured differences: approx. 16 cm at floor level, approx. 19.5 cm at a component surface, approx. 36 cm in wall height.<\/p>\n<\/li>\n
Several errors were logically impossible, for example a floor slab inside an elevator shaft.<\/p>\n<\/li>\n
Systematic errors like these cannot be fixed point by point. A rebuild from the point cloud is usually the more reliable option.<\/p>\n<\/li>\n<\/ul>\n<\/div>\n\n\n\n