Laser scanners create 3D images by sending a beam of light until it strikes an object. The light bounces back at a different wavelength than the original, allowing it to measure its distance from the object. Thousands of these processes occur simultaneously, resulting in a highly accurate point in space. As a result, a 3D image is created, which is called a point cloud.
Time-of-Flight
There are two basic principles used in measuring distance: time-of-flight (TOF) and phase-shift (PS). Both types of energy may be absorbed and reflected differently, leading to a difference in radiometric point clouds. The primary objective of this study is to compare the time-of-flight intensity data obtained by TLS and PS scanners. Multiple test samples have been used to assess their suitability for various purposes.
The geometrical data obtained from each of the four tested scanners was analyzed. For each area, a reference plane was fitted based on point cloud coordinates. Then, using an algorithm based on Mean Sum Error (MSE), the optimal reference plane was determined. This distance measurement error was then analyzed statistically, using the d-value. The accuracy of the time-of-flight data was compared with the estimated distances of the objects in the test areas.
Structured light
A structured-light 3D laser scanner is a handheld device that works by projecting patterns of light onto the object to be scanned. This pattern may be white, blue, a matrix of dots, or any other shape you choose. After scanning, the image is cleaned and stitched together. It then requires post-processing to create a digital model. These scanners are also portable and can be used on a tripod.
While both laser and structured light laser scanners to produce high-quality scans, lasers are best for home use. However, industries will probably prefer a structured light scan due to the higher-definition results and versatility. For example, it is possible to create 3D selfies by scanning someone’s face with a laser scanner, uploading the image to CAD software, and printing it out as a statuette. Companies that want to create 3D selfies should invest in structured light scanners, as these scanners are capable of capturing finer details and are ideal for medical and dental uses.
Photogrammetry
The method of Photogrammetry with a 3D laser scan differs from traditional methods in several ways. In contrast to traditional laser scanning, the technique is less susceptible to missing geometry. Unlike traditional scanning, each photograph is deliberately taken from a different position, minimizing concave areas and maximizing coverage. Moreover, photogrammetry allows you to capture inaccessible areas and target key features. In addition, the resolution of the reconstructed data can vary; areas of higher importance can be photo-graphed more densely, resulting in a more detailed mesh.
Although photogrammetry with a 3D laser scanner is a relatively simple process, it is not without disadvantages. A single camera setup can be time-consuming, because you need to manually move the camera, make sure it doesn’t miss any sections, and then import the photos into a 3D software. In addition, it doesn’t create a 3D model in real time. In addition, because of this, you may have to reset the setup a few times.
Meshing process
When using a 3D laser scanner, the data output is typically a polygonal mesh. This file type is a standard format for 3D printers and represents the surface of a shape using a large number of triangles, connected edge-to-edge. A mesh does not contain any information about the object itself. Various mesh optimization operations can be performed after the data has been captured. Read on to learn more about the various meshing operations and how they work.
The Meshing process for a 3D laser scanner starts by aligning a simple surface with existing data. The data from a laser scanner is recorded as data points in three-dimensional space, and can be converted into a computer-aided design model, often as non-uniform rational B-spline surfaces. A hand-held laser scanner can combine this data with other sensors, such as visible-light sensors, to create a 3D model that includes color and surface textures.