WHAT IS 3D LASER SCANNING?
We can answer What is 3D Laser Scanning question like; a measuring technology and measurement work that uses lasers to automatically and real-time measure the 3D coordinates of the surface of an area or object at a high speed.
3D Laser Scanning, a popular measuring method; can be used to measure small objects, land surfaces, buildings, and all kinds of different objects and collect data in the form of a point cloud consisting of millions of 3D (X, Y, Z coordinates) coordinates from the surface of the objects they measure. In other words, the data obtained by 3D Laser Scanning is in a format that can accurately represent the actual dimensions and shape of a physical object in the digital environment.
How Do 3D Laser Scanners Work?
The distance from a 3D Laser Scanner to a point on the object surface is determined by measuring with high accuracy the time elapsed between sending the laser signal to the object and detecting the same signal reflected from the object surface. The object is scanned by an optical-mechanical scanner at millions of points per second in horizontal and vertical directions, depending on the resolution setting used. The end product of this process is a highly detailed 3D image of the object, consisting of millions of densely spaced points called a point cloud. The 3D coordinates in the coordinate system are fixed at the center of the scanner and the intensity data of the reflected laser signal are recorded for each point. (Aygun, 2021)
Advantages of 3D Laser Scanning
Using 3D Laser Scanning means getting results with fewer measurement errors than traditional geodetic methods. In addition, since almost everything in the working area is measured, there is no need to go back to the area for missing or incorrect measurements.
3D Laser Scanning is very effective for projects where detailed 3D information of objects is needed and 3D models with a high level of detail will be produced. At the same time, when it is necessary to measure very large structures, objects with complex shapes, or in hard-to-reach places, the 3D Laser Scanning method is a time-saving method that provides the expected accuracy.
3D Laser Scanners Collect Data Quickly
3D Laser Scanning is one of the fastest measuring methods today. 3D Laser Scanners reduce the time and human resources required to complete measurements and can measure millions of points in seconds. Therefore, they offer a very good solution for projects that require fast work.
3D Laser Scanning Minimizes Safety and Health Risks
Geomatics engineering applications can be performed in any type of field. These include areas that pose hazards to human health and safety. In some areas, it is not possible to stay longer than a certain time and even to make classical geodetical measurements. It is very important that the professionals who make measurement applications can move safely in such fields; this situation is directly related to the method used.
3D Laser Scanning helps to overcome such problems as it is a fast measuring method without physical contact with the object. For example, in an environment where there are toxic gases harmful to human health, after setting the 3D Laser Scanner up, practitioners can move away from the working area and control the measurement remotely, if the device is in safe. Thus, the time exposed to the gas is minimized. This is achieved thanks to the fact that 3D Laser Scanners are automatic measuring devices. It is not necessary to orient the device relative to the object; 3D Laser Scanners generally have a field of view of 360° horizontally and 270° vertically and can measure every object in the field of view with high precision.
3D Laser Scanning Can Measure Inaccessible Objects
3D Laser Scanners have measuring ranges that vary according to the device. High buildings, bridges, power transmission lines, etc. can be measured with long-distance devices. Additionally, 3D Laser Scanners are classified as Mobile Laser Scanners (MLS), Terrestrial Laser Scanners (TLS), and Airborne Laser Scanners (ALS). Mobile and Aerial Laser Scanners can quickly measure structures or parts of structures inaccessible to terrestrial devices. This is also ideal for use in hazardous areas mentioned in the previous section. For example, Aerial Laser Scanners can measure unsafe sites and structures. In this way, both securities is ensured and objects in hard-to-reach positions are precisely measured.
Detailed 3D Models Can Be Produced
Detailed 3D Models are the highest quality end products that can be produced for an object. 3D CAD models can be produced by using point cloud data obtained by 3D Laser Scanning. Once the 3D model of an object, building or land is obtained with high accuracy, it can be used for all kinds of planning work. This makes the 3D Laser Scanning method one of the most reliable and functional measuring methods.
3D Laser Scanning Technologies
In order to solve practical problems in many different areas of human life, measurements must often be carried out to create real-world models. It is possible to obtain new information about the measured objects by analyzing these models. Geometric and thematic information acquired during the modeling process of objects forms the basis of decision-making processes about the objects. (Aygun, 2021)
The level of technological development we have today has changed the content and quality of the information used in many fields. All information derived about an object is not related to its location or shape. However, technological possibilities have started the process of creating data sets that have stronger meanings by integrating all kinds of information with each other. 3D information of objects and 3D information systems are gradually expanding their usage areas. Therefore, obtaining 3D information has become one of the most popular fields of study today. (Aygun, 2021)
Today, the need for 3D information containing high-intensity details is seen especially in civil engineering, architecture, historical monument projects, and industrial facilities in order to obtain the current state of some objects, sometimes even the entire structure and its environment. We can list these needs with a few items as follows:
- Monitoring the progress of construction with planning features, checking and comparing quality, especially in complex construction sites.
- Analyzing spatial relations, including the relations of buildings with their surroundings, to be able to plan in the digital environment when necessary (complex buildings, multistorey transportation centers, shopping centers, etc.).
- Creating BIM (Building Information Modeling) to ensure proper maintenance of structures, aimed at continuous construction inspection, risk assessment, and monitoring of physical deformation.
- Documentation of industrial areas called “3D virtual plant”, in other words, the creation of a full digital model of an existing industrial plant. Modern industrial facilities have a complex structure and the existence of such a virtual model is necessary for the technical development and renovation of the structure. With the 3D virtual plant, any new equipment can be programmed in the virtual environment and verified within the system without being installed in the plant or stopping other mechanisms. Necessary simulations and optimizations can be made to ensure that potential conflicts with existing mechanisms are avoided. In addition, with the help of a lifelike 3D model, it is possible to validate existing project drawings that are often outdated due to changes within the facility.
- Monitoring the deformation of engineering structures requires frequent analysis of the entire structure surface, not just the characteristic points. Thus, local deformations can be revealed.
- Providing the correct documentation necessary for detailed due diligence and damage assessment of historical monuments (churches, castles, palaces, etc.) and for the conservation or restoration of the building. The most delicate structures and details must be documented (both outdoors and indoors) in projects like this. Such studies can form the basis for the establishment of a national or worldwide information system on cultural heritage. Today, archive studies in this field are carried out on the basis of country or region.(Aygün, 2021)
- To be able to evaluate the detailed condition and damage of historical monuments (churches, castles, palaces, etc.) and to provide the correct documentation necessary for the protection or restoration of the structure. In projects like this, the most delicate structures and details must be documented (both outdoors and indoors). Such studies can form the basis for the establishment of a national or worldwide knowledge system on cultural heritage. Today, archive studies are carried out on the basis of country or region in this field. (Aygün, 2021)
Geodetical surveying devices such as total-station or GPS/GNSS are used to measure characteristic points of an object. In this measuring process, the characteristic points of the object are determined by the decision of the person using the measuring device. When the same object is measured at two different times, points of two different measurements can be detected as characteristic points that define the object, although with small differences. Geometric data of the object is obtained with these measured points. However, these devices are not suitable for studies where data must be obtained quickly. In addition, it is not possible for the measured points to contain information about the entire object.
Automatic data acquisition methods for obtaining geometric data of an object have become increasingly important in recent years. Laser Scanning Technology has revolutionized the work of acquiring 3D data for both topographic surveys and objects at close range. This new method allows an automatic and dense sampling of the object’s surface in a short time, unlike traditional techniques such as geodetic surveys and analytical photogrammetry, which must be manually interpreted during survey evaluation to obtain a representation of physical objects. With this feature, Laser Scanning Technology is way ahead of traditional measuring methods.