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Low altitude aerial photograph for use in photogrammetry. Location: Three Arch Bay, Laguna Beach, California. Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant imagery and other phenomena.
Photometric stereo analyzes multiple images of an object under different lighting conditions to estimate a normal direction at each pixel. Photometric stereo is a technique in computer vision for estimating the surface normals of objects by observing that object under different lighting conditions ().
Making a 3D-model of a Viking belt buckle using a hand held VIUscan 3D laser scanner. 3D scanning is the process of analyzing a real-world object or environment to collect three dimensional data of its shape and possibly its appearance (e.g. color).
When scanning a scene in real world using Lidar, the captured point clouds contain snippets of the scene, which requires alignment to generate a full map of the scanned environment. Point clouds are often aligned with 3D models or with other point clouds, a process termed point set registration .
In photogrammetry and computer stereo vision, bundle adjustment is simultaneous refining of the 3D coordinates describing the scene geometry, the parameters of the relative motion, and the optical characteristics of the camera(s) employed to acquire the images, given a set of images depicting a number of 3D points from different viewpoints.
Compared to 3D laser scanning, structured-light scanners can offer advantages in speed and safety by using non-coherent light sources like LEDs or projectors instead of lasers. This approach allows for relatively quick data capture over large areas and reduces potential safety concerns associated with laser use.
Lidar may operate in a fixed direction (e.g., vertical) or it may scan multiple directions, in which case it is known as lidar scanning or 3D laser scanning, a special combination of 3-D scanning and laser scanning. [3] Lidar has terrestrial, airborne, and mobile applications. [4] [5]
The feature trajectories over time are then used to reconstruct their 3D positions and the camera's motion. [12] An alternative is given by so-called direct approaches, where geometric information (3D structure and camera motion) is directly estimated from the images, without intermediate abstraction to features or corners. [13]