Three-dimensional scanning modeling process

1, three-dimensional laser scanning technology, in the traditional measurement concept, the final output measurement data is two-dimensional results (such as CAD drawing). Today, with the gradual digitalization, three-dimensional gradually replaces two-dimensional with its intuition. In recent years, with the in-depth development of measurement technology and space science, three-dimensional laser scanning technology has broken through the traditional single-point measurement method after GPS spatial positioning system. Through the high-speed laser scanning measurement method, the three-dimensional coordinate data of the measured object surface can be obtained quickly and with high resolution, which provides a brand-new technical means for quickly establishing the three-dimensional image model of the object. Based on the principle of laser ranging, 3D laser scanning technology can quickly reconstruct the 3D model of the measured object and various map data such as lines, surfaces and volumes by recording the 3D coordinates, reflectivity and textures of a large number of dense points on the surface of the measured object. Widely used in cultural relics protection, architecture, planning, civil engineering, factory renovation, interior design, building monitoring, traffic accident handling, legal evidence collection, disaster assessment, ship design, digital city, military analysis and other fields.

2. Three-dimensional scanning of buildings. As a new measuring method, 3D laser scanner can completely obtain the overall structure and morphological characteristics of buildings, and quickly and accurately obtain 3D point cloud data, which is of great significance to building measurement and planning and design. Next, taking Trimble 3D laser scanner, which is popular in the market, as an example, this paper introduces the characteristics, main technology and technical process of 3D laser scanner. Trimble 3D laser scanner has the functions of one-button operation and automatic data acquisition. Scanning speed of 6.5438+00,000 points per second; The scanning result is a three-dimensional vector, which is simple and intuitive. The workflow of Trimble 3D laser scanner is similar to the traditional measurement technology, but it also has its own characteristics. The main process and technical flow are as follows: The data finally collected by Trimble 3D laser scanner are stored in the scanner equipment in the form of point clouds and images, and the relative position information, size, texture and shape of the building are obtained through some processing by Trimble and RealWorks, and then the real building spatial data model is established.

3. Three-dimensional modeling. The point cloud data obtained by 3D laser scanner need to be modeled by 3D modeling software. Due to the particularity of point cloud data, there are not many softwares that can directly model point cloud data. At present, the three-dimensional point cloud modeling generally adopts ContextCapture. ContextCapture is a software that can automatically generate detailed 3D realistic models from simple photos and/or point clouds. Digital cameras, smart phones, laser scanners, aerial cameras and other instruments can all be used as input data sources for context capture. ContextCapture has high compatibility, and can accurately and seamlessly reconstruct various objects and data sources, from centimeter level to kilometer level, shooting from the ground or shooting from the air. As long as the resolution and accuracy of the input photos are sufficient, the generated 3D model can achieve infinite fine details. For the specific process of point cloud 3D modeling, please pay attention to the official account of "Ai 3D Technology" WeChat and view the teaching of ContextCapture software tutorial. Let's take a look at the specific function of ContextCapture: 1, which integrates geographic reference data ContextCapture and provides local support for various positioning data including GPS, markers and control points. It can also import any other positioning data through positioning/rotation import or full block import, and can accurately measure coordinates, distances, areas and volumes. 2. Automatic aerial triangulation and 3D reconstruction Once the relative position and direction of each photo are automatically identified, the aerial triangulation results can be fine-tuned by adding control points and editing connection points, thus maximizing the geometric and geospatial accuracy. The optimized 3D reconstruction algorithm generates the accurate 3D model and image texture of each mesh with unparalleled accuracy. ContextCapture can ensure that the vertices of each 3D mesh model are placed in the best position, so it can reproduce finer details and sharper edges with fewer defects, thus greatly improving the geometric accuracy.

4. Generate 2D and 3D, GIS, models With the help of ContextCapture, you can generate accurate geo-referenced 3D models in various formats, including real aerial images and new images, cesium, 3D, slicing, and export the slicing range and spatial results to KML and XML. ContextCapture and the provided coordinate database interface can ensure data interoperability with GIS and solutions. You can choose from, 4,000 and multiple spatial reference systems, and you can add user-defined coordinate systems. Moreover, ContextCapture will automatically adjust the resolution and accuracy of the model according to the resolution and spatial distribution of the input photos. This means that ContextCapture can handle scenes with uneven resolution without sacrificing overall efficiency to preserve some scene areas with higher resolution.

5. Processing the real scene model ContextCapture can quickly and conveniently process the grid model of any scale, generate cross sections, extract terrain and fracture lines, and generate orthographic images, 3D, PDF, harmony, modal and so on. It can combine grid model with geographic information system and engineering data, and realize intuitive search, navigation, visualization and animation of this information in the visualization environment of grid model.

6. Processing point clouds can enhance, segment and classify point clouds and combine them with engineering models. Then, the advanced 3D modeling, profile cutting, fracture line and terrain extraction functions of ContextCapture are used to quickly and efficiently model the completion conditions and support the design process. Therefore, ContextCapture can better evaluate point clouds and generate more accurate engineering models. You can also generate animations and render them for display. 6. Generating and processing large-scale scalable terrain model ContextCapture can generate very large scalable terrain models from various sources, including point clouds, polylines, raster digital elevation models and existing irregular triangulation. By synchronizing with the original data source, the extensible terrain model can be updated to the latest in real time. The value of this is to present all data globally, up-to-date and comprehensively, and use various display modes to perform analysis, animation and visualization.

7. Generate 3D, CAD and models Generate 3D models based on various CAD, formats, 3D general formats, DSM and dense 3D point clouds to ensure that the models can be accessed in the modeling environment. In addition, it can also generate a multi-resolution mesh model composed of billions of triangular patches, and Bentley and series of platform software natively support the mesh model data. Including MicroStation, Descartes, AECOsim, Building, Designer, OpenRoads, OpenPlant, Bentley, Map? , Bentley, substation, etc.

8. Publishing and viewing support, Web and model With the help of ContextCapture, users can generate real models of any size optimized for network publishing and view them in the browser. Such as ContextCapture, native format of 3MX, or, cesium, 3D, Tiles. In this way, you can enjoy the 3D model with any stakeholders at any time and display it intuitively.