laser point cloud
Massive point collection expressing target spatial distribution
Laser point cloud, also known as point cloud, uses laser to obtain the spatial coordinates of each sampling point on the surface of the object in the same spatial reference system, and obtains a series of mass point collections that express the spatial distribution of the target and the characteristics of the target surface. The collection is called "Point Cloud".
Properties of the point cloud
Including: spatial resolution, point accuracy, surface normal vector, etc.
(1) The point cloud obtained according to the principle of laser measurement, including three-dimensional coordinates (XYZ) and laser reflection intensity (Itensity).
(2) The point cloud obtained according to the principle of photogrammetry, including three-dimensional coordinates (XYZ) and color information (RGB).
(3) Combining the principles of laser measurement and photogrammetry to obtain point clouds, including three-dimensional coordinates (XYZ), laser reflection intensity (Itensity) and color information (RGB).
Point cloud technology was mostly used in the machinery manufacturing industry at first. With the improvement of computer capabilities in recent years, not only the number of processing points has increased, but the price of point cloud equipment has also decreased. Acquisition equipment that used to be worth hundreds of thousands of dollars is now only It costs thousands of dollars, and the accuracy is getting higher and higher, and there are more and more places that can be photographed. Now it can be directly applied to construction and other fields. The application of point cloud can not only save the traditional modeling time, but also increase the accuracy of the model. Regarding the application of point cloud, Yun Langsheng, director of the core engineering project of Autodesk China Research Institute, commented: "We used to make virtual things real, but now we virtualize real things. It is a virtual and real world." Combination, which is what we discussed a lot in the summit.”
The acquisition methods of point cloud data mainly include vehicle laser, airborne laser and ground laser scanning. Ground laser scanning and airborne laser scanning are relatively mature, and the vehicle-mounted laser scanning system is still being improved in China. Different laser point cloud data acquisition methods have their own advantages and disadvantages.