Point clouds: LAS, LAZ and classification
What is a point cloud, what do LAS and LAZ mean, and why is classification useful?
A point cloud is a collection of millions of 3D points with coordinates (X, Y, Z) and often colour. It is the raw 3D result of photogrammetry or LiDAR.
LAS and LAZ
LAS is the standard format for point clouds. LAZ is its compressed version: the same data, much smaller files. Both are read by all common software.
Classification
Classification assigns a class to each point: ground, vegetation, building, and so on. By isolating the ground points we obtain a pure digital terrain model (DTM), without trees or buildings.
What do you do with it?
From a point cloud we derive cross-sections, contour lines, volumes and plans — the building blocks of almost any survey file.