Nowadays, various advanced technologies are gradually applied in engineering surveying and mapping, and lidar surveying and mapping technology is also included. Relatively speaking, the application of lidar surveying and mapping technology in engineering surveying and mapping is quite successful, which greatly improves the level of engineering surveying and mapping. Generally, in order to correctly understand the actual spatial location in engineering surveying and mapping, the staff needs to complete the surveying and mapping of all points.
1 Introduction to Engineering Surveying and Mapping Technology of Lidar
Surveying and mapping mainly refers to the premise of electronic communication technology, computer technology and other advanced technologies, with GPS, GIS, RS as the core, the use of measurement to obtain the location information and graphic information of the measured object, and the calculation, processing and collection of data for strengthening The management and planning of project construction lay a solid foundation.
Lidar surveying and mapping technology, also known as LIDAR, uses electromagnetic waves to send signals to the measured location. Through the process of comparing the previously sent signals with the received signals, the height, width, distance and object of the measured object are at a standstill or The movement status is accurately calculated to achieve the purpose of surveying and tracking the measured object. Lidar surveying and mapping technology can obtain three-dimensional spatial coordinates at the same time, so that it can achieve the effect of synchronization. It uses point cloud processing and modeling software such as RealWorks, Pointools, and 3dsMax to achieve a complete set of digital models.  This advanced digital model can obtain high-precision three-dimensional digital information that cannot be measured by traditional measurement methods. It has the characteristics of accuracy, fast speed and wide application fields. Combining lidar surveying and mapping technology with virtual reality technology can monitor natural disasters around the clock, such as earthquakes, droughts and floods, etc., and make timely warnings for disaster relief and prevention. It can also be applied in engineering construction to truly realize intelligent management Traffic safety system, reasonable planning of the overall layout of the city, and further promotion of environmental protection.
2 Basic principles of lidar surveying and mapping technology
Lidar surveying and mapping technology is to use light waves to complete various surveying and mapping tasks. The transmission distance of light waves is longer. Compared with conventional light waves that are easily affected, the collection work has stronger safety. When the surface of the measured object receives light waves, some of the reflected light can be transmitted to the radar receiver. The radar receiving system can combine the relevant data of the reflected light to calculate the actual distance from the light wave to the measured object. And the global positioning system is very important in the lidar surveying and mapping system. It can receive all the position information obtained by the lidar surveying and mapping system in time, and can accurately locate the actual coordinates of the measured object with a certain degree of accuracy. Measuring the distance of two or more than two can be combined with the actual movement trajectory of the measured object to obtain the moving speed of the measured object.
3 Practical application of lidar surveying and mapping technology in engineering surveying and mapping
In recent years, the process of urbanization has been accelerating, and the types of projects have also been diversified, which has led to the stable development of my country’s construction industry, and the engineering surveying and mapping industry related to engineering construction has also achieved healthy development. The rapid development of lidar surveying and mapping technology is increasing. To a certain extent, it provides a strong guarantee for engineering surveying and mapping.  At present, lidar surveying and mapping technology has been widely used in engineering surveying and mapping, including precision surveying and mapping, mine surveying and mapping, and basic surveying and mapping.
(1) Precision surveying and mapping. Generally, precision engineering surveying and mapping mainly include settlement measurement and building surveying, etc. These precision engineering surveying and mapping often involve the collection of measurement targets and the construction of three-dimensional object models. Whether building a three-dimensional object model or collecting measurement targets, it is required to analyze, extract, and model on the basis of accurate surveying and mapping data. The use of lidar surveying and mapping technology can stably obtain high-precision, full-element, and multi-dimensional high Density surveying and mapping data can almost meet the requirements of precision engineering surveying and mapping.
(2) Mine surveying and mapping. The management of mineral resources and industries is related to the sustainable development of resource cities to a certain extent. The ecological environment of mines is getting worse and worse, which will also hinder the construction of mines to a certain extent.  Therefore, it is particularly important to enhance the digital construction of mines. Apply lidar mapping technology to collect all data inside the mine in a short period of time, use Bentley Pointools to build a three-dimensional digital model, clarify the actual status of the mine, extract ground models and mine models, and apply GIS to conduct economic and environmental analysis of severely damaged mine areas , Focus on monitoring the damage degree of the collapsed location, and realize the risk warning of possible disasters.
(3) Basic surveying and mapping. In the basic surveying and mapping process, it is first necessary to cut and reflect the digital information of the measured object, and form the initial surveying paper based on this premise.  The most critical tasks in this process are digital measurement and digital photography, and these tasks are complex and systematic. In order to ensure the accuracy of surveying and mapping data, it is necessary to rationally design the surveying and mapping circuit based on the actual situation.  Lidar surveying and mapping technology can improve the accuracy of the ground 3D coordinates and meet the requirements of high-precision image differential correction without digital photogrammetry. The digital orthophoto can be obtained, which not only simplifies the complicated surveying and mapping environment, but also reduces the work cost. In addition, lidar surveying and mapping technology uses high-precision laser point cloud data, which can directly reflect all three-dimensional information of towers, houses, roads, water tanks and other objects, which are all required for basic surveying and mapping.
Compared with traditional measurement technology, lidar has special characteristics and can obtain high-precision, all-element, high-density spatial information more quickly, so it has a strong advanced nature in application. With the advancement of engineering technology and the improvement of basic data requirements, lidar surveying and mapping technology is bound to become the main method of obtaining three-dimensional spatial information. With the continuous progress and development of lidar surveying and mapping technology, the application of ground lidar and airborne lidar will become more popular and widespread, the cost will gradually decrease, and the operation will be easier, which can promote the technology of the engineering surveying and mapping industry to a certain extent development of.