Point cloud
The dense set of measured 3D points from a laser scan or photogrammetry — the digital "as-is" of a real space.
A point cloud is a large set of individual 3D points that together describe the shape and surface of a real object or space. Each point carries X, Y and Z coordinates and often extra attributes — intensity, colour, classification — so the cloud is a dense, measured snapshot of how something actually exists, not how it was drawn.
It is produced by reality-capture survey. Laser scanning (LiDAR) measures the returns of a laser beam to place points in space; photogrammetry derives the same points from many overlapping photographs. Depending on scale and accuracy, the capture can be terrestrial, mobile, handheld or airborne. The cloud then becomes the "as-is" reference a modeller traces over — walls, slabs, openings, services — which is exactly why it is the starting point of scan to BIM and of an as-built model.
For interchange the preferred formats are open and vendor-neutral: E57 (behind it the ASTM E2807 specification), which stores points plus attributes and often imagery, and LAS / LAZ, the open LiDAR interchange format (LAZ is its compressed form); the text-based PTS is common but less formally standardised. In Italian practice the point cloud is the nuvola di punti.
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