3D scanning is a process of capturing the shape and appearance of real-world objects or environments to create digital representations in three dimensions. It involves using various techniques and devices to collect data about the geometry, texture, and color of a physical object or space.

The basic principle behind 3D scanning is to measure multiple points on the surface of an object or within a given area to create a point cloud. A point cloud is a collection of data points in three-dimensional space that represents the object's surface or the environment. These data points can be obtained using different technologies such as laser scanners, structured light scanners, photogrammetry, or even depth-sensing cameras.

Here's a brief overview of a few common 3D scanning techniques:

1. Laser Scanning: This method uses lasers to measure the distance to an object's surface. It involves sweeping a laser beam across the object and measuring the time it takes for the laser to bounce back. This data is then used to create a point cloud.
2. Structured Light Scanning: In this technique, a projected pattern of light (typically grids or stripes) is used to illuminate the object. A camera captures the distorted pattern, and the deformation is used to calculate the object's shape and depth information.
3. Photogrammetry: This approach involves capturing a series of photographs of an object or a scene from different angles. Specialized software analyzes the images, identifies common points, and triangulates their positions to reconstruct the 3D shape.

Once the 3D data is obtained, it can be processed and transformed into a digital 3D model using specialized software. The resulting model can be used for various applications, such as visualization, virtual reality, animation, reverse engineering, quality control, prototyping, and many others.