A multi-scenario three-dimensional model and 3D point cloud coordinate conversion system

Abstract

The present invention provides a multi-scene 3D model and 3D point cloud coordinate conversion system, including ground control point layout; building control point layout; coordinate conversion system establishment; and model accuracy assessment. This system can be applied to coordinate conversion between design models and actual construction models in projects such as bridges, tunnels, building construction, and subways. By comparing the design and actual models, it can identify engineering entity problems within the construction entity, assisting in full-process project management and addressing the inefficiency of existing methods, large model coordinate conversion errors, and the time-consuming calculation requirements. This system belongs to the field of civil engineering.

Description

Technical Field

[0001] The present invention relates to a multi-scene three-dimensional model and 3D point cloud coordinate conversion system, which is particularly suitable for three-dimensional geographic coordinate conversion between data such as BIM models, drone real-scene models, lidar point clouds, and 3D scanning point clouds in multiple scenes, and belongs to the field of civil engineering. Background Art

[0002] With the gradual development of informatization in the construction industry, BIM three-dimensional modeling can accurately express the three-dimensional spatial geometric relationship of buildings in the design stage in advance, and the most realistic design model or theoretical model can be displayed. However, its coordinates are arbitrarily defined and do not include geographical attributes, that is, the spatial position relationship of the building. Drone real-life models, drone lidar point clouds, and three-dimensional laser point clouds can most realistically express the existing status of the building after construction, and there are certain differences between them and the design model. Therefore, in order to most effectively compare the design model with the actual model, it is necessary to solve the precise coordinate conversion technology between different types of three-dimensional models and three-dimensional point clouds, so as to realize the difference analysis between theoretical models and theoretical models. At present, the commonly used three-dimensional model coordinate conversion method is mainly to solve the rotation, translation, and scaling between multiple common points. Its work efficiency is low, the model coordinate conversion error is large, and it takes a lot of time to calculate. Summary of the Invention

[0003] The present invention provides a multi-scene three-dimensional model and 3D point cloud coordinate transformation system to solve the problems of low efficiency of existing methods, large errors in model coordinate transformation, and a large amount of time required for calculation.

[0004] To achieve the above objectives, a multi-scene 3D model and 3D point cloud coordinate transformation system is proposed, as follows:

[0005] 1) Ground control point layout

[0006] Ground control points are located in relatively flat areas. 50cm*50cm black and white PCT plates are fixed to the control points. Simple railings with a height of 30cm are placed around the control points. The railings are welded from 10cm diameter round steel. For soft soil areas, the control points are arranged as observation piers. The excavation surface of the observation pier is 50cm*50cm and 60cm deep. Control point markers with crosshairs are embedded in the observation piers. 50cm*50cm PCT plates are fixed to the control points on the surface of the observation piers, and temporary protective railings are installed.

[0007] 2) Layout of control points on the building

[0008] For the layout of control points on the building, the control points are arranged in the shape of a circle with a diameter of 40 cm, and the circle is divided into four equal parts along the center of the circle. The diagonal areas are set to black and white respectively. For building construction projects, the control points are parallel to the bottom of the window; for bridge projects, the control points are arranged in combination with the single casting height of the pier, and are arranged at the center of the casting line of half the total height of the pier.

[0009] 3) Establishment of a multi-purpose coordinate transformation system

[0010] For the coordinate transformation between different benchmark 3D models and 3D point clouds, the 3D coordinates (x, y, z) of three known common points are required. The 7-parameter values between any coordinates are solved by the Bursa model, and the known points are the coordinate values of the control points. For roadbed projects and road projects, 4 square navigation marks are laid on the ground, and one point is used to detect the coordinate accuracy; for bridge projects and construction projects, 2 navigation marks are laid on the ground and 2 circular marks are laid on the building, and 1 circular mark is used to detect the coordinate transformation accuracy; for tunnel projects and underground projects, 1 square navigation mark is laid on any ground, 1 square navigation mark is laid at the tunnel entrance with the minimum mileage, and 1 square navigation mark is laid at the tunnel entrance with the maximum mileage. 1 circular mark is laid on the road inside the tunnel, and the circular mark is used to check the alignment accuracy.

[0011] 4) Model accuracy assessment

[0012] Since BIM models, drone real-life models, lidar point clouds, and 3D scanning point clouds all express the three-dimensional dimensions of spatial objects at a 1:1 ratio, it is only necessary to solve three translation parameters and three rotation parameters. Based on the six parameters solved from three known points, one of the models is translated along the X-axis, Y-axis, and Z-axis at the same time. Then, the coordinate rotation angles between the X-axis, Y-axis, and Z-axis are adjusted respectively to obtain a new model after coordinate transformation. The coordinates of the fourth control point are measured through coordinate measurement, and the transformed coordinate values are compared to determine the coordinate transformation accuracy between the three-dimensional data.

[0013] Compared with the existing technology, the present invention can effectively solve the accurate conversion between BIM models, drone real-life models, lidar point clouds, and 3D scanning point clouds in different scenarios under arbitrary coordinates. It can realize the comparison between the building design model and the actual model, discover the engineering entity problems in the construction subject, and assist the whole process management of the project. It has many advantages such as real and reliable data, high data accuracy, high work efficiency, and low cost. This method helps to improve the level of project construction management, and its social and economic benefits are significant. It has important guiding significance and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a process flow chart of the present invention;

[0015] Figure 2 This is a schematic diagram of navigation aid layout in multiple scenarios. DETAILED DESCRIPTION

[0016] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] Example

[0018] Reference Figure 1 and Figure 2 This embodiment provides a multi-scene 3D model and 3D point cloud coordinate conversion system, as follows:

[0019] (1) Ground control point layout

[0020] The layout of ground control points requires comprehensive consideration of the joint use of drone mapping beacons and three-dimensional laser scanning targets. They should be placed in areas with relatively flat terrain. If conditions permit, they can be placed on hardened areas such as bridge abutments, building roofs, and tunnel entrances. 50cm*50cm black and white PCT plates should be fixed to the control points. Simple railings with a height of 30cm should be laid around the control points. They should be welded from round steel with a diameter of 10cm to prevent construction workers from stepping on or damaging the control points. For soft soil areas, control points should be arranged as observation piers with an excavation surface size of 50cm*50cm and a depth of 60cm. Control point markers with crosshairs should be pre-buried. On the surface of the observation pier, 50cm*50cm PCTs should be fixed to the control points, and temporary protective railings should be installed.

[0021] (2) Layout of control points on the building

[0022] For the placement of control points on buildings (bridges), due to their overall structural stability and near-zero spatial deformation, the control points are arranged in the form of a 40cm diameter circle, divided along its center into four equal parts. The diagonal areas are painted black and white, respectively, and are made of waterproof fabric. For building construction projects, control points should be placed parallel to and close to the bottom of the windows. For bridge projects, control points should be placed in conjunction with the single pouring height of the piers, at the center of the pouring line at half the total height of the piers. This facilitates marking the exact location of navigation marks on the BIM model, effectively ensuring the accuracy of coordinate conversion between 3D models.

[0023] (3) Establishment of a multi-purpose coordinate transformation system

[0024] Coordinate transformations between different benchmark 3D models and 3D point clouds require the 3D coordinates (x, y, z) of three known common points. The Bursa model is used to solve the seven-parameter values between any coordinates, with the known points serving as the coordinate values of the control points. For roadbed and road projects, four square navigation marks should be deployed on the ground, one of which is used to check coordinate accuracy. For bridge and construction projects, two navigation marks should be deployed on the ground, and two circular marks should be placed on the building, one of which is used to check coordinate transformation accuracy. For tunnel and underground projects, one square navigation mark should be deployed on any ground surface, one at the tunnel entrance with the minimum mileage, one at the tunnel entrance with the maximum mileage, and one circular mark on the tunnel's internal roadway to verify registration accuracy.

[0025] (4) Model accuracy assessment

[0026] Since BIM models, drone-based real-life models, lidar point clouds, and 3D scanning point clouds all express the three-dimensional dimensions of spatial objects at a 1:1 ratio, there is no scaling of the three-dimensional data under different coordinate bases. Therefore, only three translation parameters and three rotation parameters need to be solved. Based on the six parameters solved from the three known points, one of the models is translated simultaneously along the X-axis, Y-axis, and Z-axis. The coordinate rotation angles between the X-axis, Y-axis, and Z-axis are then adjusted to obtain a new model after coordinate transformation. The coordinates of the fourth control point are measured through coordinate measurement, and the transformed coordinate values are compared to determine the accuracy of the coordinate transformation between the three-dimensional data.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-scene 3D model and 3D point cloud coordinate conversion system, characterized in that: The details are as follows: 1) Ground control point layout 2) Layout of control points on the building 3) Establishment of a multi-purpose coordinate transformation system For the coordinate transformation between different benchmark 3D models and 3D point clouds, the 3D coordinates (x, y, z) of three known common points are required. The 7-parameter values between any coordinates are solved by the Bursa model. The known points are the coordinate values of the control points. For roadbed projects and road projects, 4 square navigation marks are laid on the ground, and one point is used to detect the coordinate accuracy; for bridge projects and construction projects, 2 navigation marks are laid on the ground and 2 circular marks are laid on the building, and 1 circular mark is used to detect the coordinate transformation accuracy; for tunnel projects and underground projects, 1 square navigation mark is laid on any ground, 1 square navigation mark is laid at the tunnel entrance with the minimum mileage, 1 square navigation mark is laid at the tunnel entrance with the maximum mileage, and 1 circular mark is laid on the road inside the tunnel, and the circular mark is used to check the alignment accuracy; 4) Model accuracy assessment Since BIM models, drone real-life models, lidar point clouds, and 3D scanning point clouds all express the three-dimensional dimensions of spatial objects at a 1:1 ratio, it is only necessary to solve three translation parameters and three rotation parameters. Based on the six parameters solved from three known points, one of the models is translated along the X-axis, Y-axis, and Z-axis at the same time. Then, the coordinate rotation angles between the X-axis, Y-axis, and Z-axis are adjusted respectively to obtain a new model after coordinate transformation. The coordinates of the fourth control point are measured through coordinate measurement, and the transformed coordinate values are compared to determine the coordinate transformation accuracy between the three-dimensional data.

2. A multi-scene 3D model and 3D point cloud coordinate conversion system according to claim 1, characterized in that ,The layout of control points is as follows: 1) Ground control point layout Ground control points are located in relatively flat areas. 50cm*50cm black and white PCT plates are fixed to the control points. Simple railings with a height of 30cm are placed around the control points. The railings are welded from 10cm diameter round steel. For soft soil areas, the control points are arranged as observation piers. The excavation surface of the observation pier is 50cm*50cm and 60cm deep. Control point markers with crosshairs are embedded in the observation piers. 50cm*50cm PCT plates are fixed to the control points on the surface of the observation piers, and temporary protective railings are installed. 2) Layout of control points on the building For the layout of control points on the building, the control points are arranged in the shape of a circle with a diameter of 40 cm, and the circle is divided into four equal parts along the center of the circle. The diagonal areas are set to black and white respectively. For building construction projects, the control points are parallel to the bottom of the window; for bridge projects, the control points are arranged in combination with the single casting height of the pier, and are arranged at the center of the casting line of half the total height of the pier.

Images