阅读说明：本技术 一种用于路桥施工领域的无人机倾斜摄影测量方法 (Unmanned aerial vehicle oblique photography measurement method used in road and bridge construction field ) 是由 赵尚哲 隋欣 冯宝成 方立志 陈壮 于 2021-08-13 设计创作，主要内容包括：一种用于路桥施工领域的无人机倾斜摄影测量方法,包括如下步骤：步骤①：软硬件设备选择(1)；步骤②：无人机倾斜摄影参数确定；步骤③：无人机倾斜摄影航线规划(7)；步骤④：数据处理；步骤⑤：三维实景模型及产品直接应用(12)；步骤⑥：三维数字模型与BIM结合(13)；步骤⑦：航飞后对生成的模型进行了精度检验。本发明具有提高测量效率、降低测量作业安全风险、降低施工成本等优点。在大比例尺地形测图、获取高分辨率影响方面有着明显优势,可极大地减少测绘外业工作量,大幅度提高工作效率。(An unmanned aerial vehicle oblique photography measurement method for the field of road and bridge construction comprises the following steps: the method comprises the following steps: selecting software and hardware equipment (1); step two: determining tilt photography parameters of the unmanned aerial vehicle; step three: planning an unmanned aerial vehicle oblique photography route (7); step IV: processing data; step five: the three-dimensional live-action model and the product are directly applied (12); step (c): combining (13) the three-dimensional digital model with BIM; step (c): and (4) carrying out precision inspection on the generated model after aviation. The invention has the advantages of improving the measurement efficiency, reducing the safety risk of measurement operation, reducing the construction cost and the like. The method has obvious advantages in the aspects of mapping the large-scale terrain and acquiring high-resolution influence, can greatly reduce the workload of mapping field work, and greatly improves the working efficiency.)

1. An unmanned aerial vehicle oblique photography measurement method for the field of road and bridge construction is characterized by comprising the following steps:

the method comprises the following steps: selecting software and hardware equipment (1);

step two: determining tilt photography parameters of the unmanned aerial vehicle;

step three: planning an unmanned aerial vehicle oblique photography route (7);

step IV: processing data;

step five: the three-dimensional live-action model and the product are directly applied (12);

step (c): combining (13) the three-dimensional digital model with BIM;

step (c): and (4) carrying out precision inspection on the generated model after aviation.

2. The unmanned aerial vehicle oblique photogrammetry method for road and bridge construction field according to claim 1, characterized by comprising the following steps:

the method comprises the following steps: selecting software and hardware equipment (1);

firstly, selecting types of aircrafts, and selecting an unmanned aerial vehicle (2) suitable for construction site conditions and Context-Capture modeling software (3) of Bentley company according to brands and different models of unmanned aerial vehicles (2) on the market;

step two: determining tilt photography parameters of the unmanned aerial vehicle;

the image accuracy (4) is determined on the basis of the planning model accuracy, and in order to achieve a predetermined image accuracy (4), the focal length (5) and the shooting distance (6) have to be determined, according to the following formula:

the image accuracy (4) is the focal length (5) and the maximum size of the image is the sensor width, the shooting distance (6).

Step three: planning an unmanned aerial vehicle oblique photography route (7);

before aviation, the overall landform and the ground objects of the project area are comprehensively analyzed, a flight route is formulated, the aviation shooting height and the image overlapping degree are planned, and the aviation height calculation formula is as follows:

in the formula: ls ═ sensor length (m);

d ═ the distance (m) between the camera and the object;

f is the focal length of the digital camera;

l ═ image length (Px);

step IV: data processing:

after the aviation flight is finished, the acquired image data is subjected to internal processing, and the data processing technology comprises the main technical contents of air-space three-dimensional calculation of the airline images (8), multi-view image dense matching (9), TIN triangulation network generation (10) and texture mapping (11), so that the real product data is finally obtained.

Air-to-air triple calculation of the route image (8);

the oblique photography space-three basic principle is basically the same as the traditional aerial survey space-three basic principle, and is divided into two parts of continuous point extraction and space-three solution, the oblique photography causes great deformation between photos, and the matching difficulty of connecting points is increased, but the oblique photography is generally five-aerial with different angles, and the quantity of points with the same name is increased by four times, so the relation between unknowns is complex, and a popular basic algorithm along with the development of the technology in recent years is as follows:

in the formula: [ X ]_A Y_A Z_Z]^TRepresenting the coordinates of the image point in a space coordinate system; λ is a projection coefficient; r is an orthogonal transformation matrix formed by the angle elements of the exterior orientation elements,for the time of flight shooting the GPS position,representing the speed of the drone in three directions, [ X Y Z]^TCoordinates representing an auxiliary coordinate system of the image space, Δ t representing a camera exposure delay;

multi-view dense matching (9);

the multi-view dense matching (9) algorithm is an SGM semi-global matching algorithm or a PMVS multi-view matching algorithm.

Constructing a triangular network TIN (10);

the triangulation network (10) is divided into two stages: firstly, point cloud data comprises constraint points to jointly establish a triangular network; secondly, carrying out diagonal exchange by taking line elements obtained by image matching as constraint conditions, and adjusting each line segment in the triangulation network by using a local optimal process LOP to form a TIN triangulation network (10) with the constraint conditions;

a texture map (11);

the essence of the texture mapping (11) is that a shot image is processed to generate a texture image, a corresponding relation of two space points is established through a certain mathematical relation, the two space points are respectively a space point of a two-dimensional texture and a space point of a three-dimensional model, and finally the texture image is attached to the three-dimensional model to form a vivid three-dimensional model; texture mapping can be divided into forward and reverse mapping according to the mapping direction.

After the image data are processed and modeled by a data platform, a series of models or data can be generated according to actual needs;

after the three-dimensional live-action model is generated, format conversion is needed, common formats are OSGB and OBJ, the three-dimensional model can be guided into an application platform after the conversion is completed, and the three-dimensional model can also be subjected to deep processing again, so that texture modification, mapping and model splicing are carried out on the model.

Step five: the three-dimensional live-action model and the product are directly applied (12);

through the three-dimensional live-action model after flying, multiple functions and applications can be realized: (1) performing earth and stone square rechecking rapidly; (2) directly measuring the terrain data in the field; (3) carrying out on-site investigation analysis and scheme formulation on emergency rescue and disaster relief conditions; (4) flood risk assessment and simulation and disaster prevention scheme making; (5) analyzing buffer areas under different thresholds; (6) dynamic data management and present situation analysis; (7) other applications related to GIS.

Step (c): combining (13) the three-dimensional digital model with BIM;

the point cloud data generated through the three-dimensional model can be imported into Civil3D, and after a high-precision terrain curved surface is generated, roads and terraces are created according to design files, so that fast earth and stone calculation and various slope calculation can be realized;

selecting Bentley Lumen RT software to fuse the three-dimensional live-action model with Revit, programming by using Dynamo, reading bridge design parameters, and placing a parameterization family, thereby solving the problem of short plates of Revit in bridge modeling at the present stage. After the bridge modeling is finished, the Revit model is converted into a format accepted by a corresponding platform, and after the Revit model is imported into an operation platform, fusion of the Revit project and the three-dimensional live-action model can be realized;

step (c): after aviation, the generated model is subjected to precision inspection;

in order to reduce the influence of projection difference on the accuracy of the image matching result, the position where the image control points are arranged should be 1-2cm away from the image boundary; the specific method for loading the corrected three-dimensional model into the Contex-tCapture-Viewer software comprises the following steps: taking 5 times of measurement on each check point position respectively, taking coordinate values actually measured in the industry as true values, and combining the measured coordinate values of 5 times to obtain errors in the check point positions, wherein a calculation formula is as follows:

in the formula: m is the error in the checkpoint;

xi, yi are plane coordinate values acquired at the ith time on the three-dimensional model;

x and Y are measured check point values.

Technical Field

The invention relates to the field of road and bridge construction, in particular to an unmanned aerial vehicle oblique photography measurement method used in the field of road and bridge construction.

Background

A new measurement technology, namely an oblique photogrammetry technology, developed in recent years changes the limitation that the influence of the traditional aerial remote sensing can only be shot from the vertical direction, and the oblique photogrammetry technology utilizes a plurality of sensors to acquire data from different angles, so that massive data information can be efficiently and quickly acquired, the objective situation of the ground can be truly and reliably reflected, and the requirement of people on three-dimensional information can be met.

However, the current oblique photogrammetry techniques suffer from the following significant disadvantages: the measuring efficiency is low, the measuring operation safety risk is high, and the construction cost is high.

Disclosure of Invention

The invention provides an unmanned aerial vehicle oblique photography measurement method used in the field of road and bridge construction.

An unmanned aerial vehicle oblique photography measurement method for the field of road and bridge construction comprises the following steps:

the method comprises the following steps: selecting software and hardware equipment (1);

step two: determining tilt photography parameters of the unmanned aerial vehicle;

step three: planning an unmanned aerial vehicle oblique photography route (7);

step IV: processing data;

step five: the three-dimensional live-action model and the product are directly applied (12);

step (c): combining (13) the three-dimensional digital model with BIM;

step (c): and (4) carrying out precision inspection on the generated model after aviation.

Has the advantages that:

the invention has the advantages of improving the measurement efficiency, reducing the safety risk of measurement operation, reducing the construction cost and the like. The method has obvious advantages in the aspects of mapping the large-scale terrain and acquiring high-resolution influence, can greatly reduce the workload of mapping field work, and greatly improves the working efficiency.

Drawings

FIG. 1 is a flow chart of the application of the oblique photogrammetry technique of the unmanned aerial vehicle for the road and bridge construction field;

FIG. 2 is a schematic diagram of the unmanned aerial vehicle oblique photogrammetry technology earth and stone rechecking and engineering quantity quick estimation used in the field of road and bridge construction;

fig. 3 is a schematic diagram of three-dimensional measurement of topographic data by an unmanned aerial vehicle oblique photogrammetry technology, which is used in the field of road and bridge construction.

The symbols in the drawings mean: 1. selecting software and hardware equipment; 2. an unmanned aerial vehicle; 3. modeling software; 4. image precision; 5. a focal length; 6. shooting distance; 7. planning an unmanned aerial vehicle oblique photography route; 8. calculating the air route image air route; 9. performing multi-view image dense matching; 10. constructing a triangular network TIN; 11. mapping textures; 12. the three-dimensional live-action model and the product are directly applied; 13. The three-dimensional digital model is combined with BIM.

Detailed Description

The present invention will be described in detail below with reference to the attached drawings, and the technical solutions in the embodiments will be clearly and completely described. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

An unmanned aerial vehicle oblique photography measurement method for the field of road and bridge construction comprises the following steps:

the method comprises the following steps: selecting software and hardware equipment (1);

step two: determining tilt photography parameters of the unmanned aerial vehicle;

step three: planning an unmanned aerial vehicle oblique photography route (7);

step IV: processing data;

step five: the three-dimensional live-action model and the product are directly applied (12);

step (c): combining (13) the three-dimensional digital model with BIM;

step (c): and (4) carrying out precision inspection on the generated model after aviation.

Example 1

An unmanned aerial vehicle oblique photography measurement method for the field of road and bridge construction comprises the following steps:

the method comprises the following steps: software and hardware equipment selection (1):

firstly, the type of the aircraft is selected, and the unmanned aerial vehicle (2) suitable for the conditions of a construction site is selected according to the brand and different types of the unmanned aerial vehicle (2) on the market. Preferentially selecting the unmanned aerial vehicle (2) with stable flight, strong cruising ability, high pixel precision (4) and high positioning precision.

International mainstream modeling software (3): the software is based on rapid three-dimensional scene operation software of a graphic operation unit GPU, can be used for calculating and generating ultra-high density point cloud based on real images, can generate a vivid three-dimensional scene model from simple continuous images without manual intervention, and can also generate a series of format data such as point cloud data, DSM (digital surface model), DEM (digital elevation model), orthoimage and the like through modeling software (3).

Step two: determining unmanned plane oblique photography parameters:

since the image accuracy (4) is determined according to the planning model accuracy, the focal length (5) and the shooting distance (6) must be determined in order to achieve the predetermined image accuracy (4), as follows:

the image accuracy (4) is the focal length (5) and the maximum size of the image is the sensor width, the shooting distance (6).

Step three: unmanned aerial vehicle oblique photography route planning (7):

before aviation, the overall landform and the ground objects of the project area are comprehensively analyzed, a flight route is formulated, the aviation shooting height and the image overlapping degree are planned, and the aviation height calculation formula is as follows:

in the formula: ls ═ sensor length (m);

d ═ the distance (m) between the camera and the object;

f is the focal length of the digital camera;

l ═ image length (Px);

step IV: data processing:

after the aviation flight is finished, the acquired image data is subjected to internal processing, and the data processing technology comprises main technical contents such as air route image air-to-three calculation (8), multi-view image dense matching (9), TIN triangulation network generation (10), texture mapping (11) and the like, so that real product data is finally obtained.

Air-space three-dimensional calculation of route images (8):

the oblique photography space-three basic principle is basically the same as the traditional aerial survey space-three basic principle, and is divided into two parts of continuous point extraction and space-three solution, the oblique photography causes great deformation between photos, and the matching difficulty of connecting points is increased, but the oblique photography is generally five-aerial with different angles, and the quantity of points with the same name is increased by four times, so the relation between unknowns is complex, and a popular basic algorithm along with the development of the technology in recent years is as follows:

in the formula: [ X ]_A Y_A Z_Z]^TRepresenting the coordinates of the image point in a space coordinate system; λ is a projection coefficient; r is an orthogonal transformation matrix formed by the angle elements of the exterior orientation elements,for the time of flight shooting the GPS position,representing the speed of the drone in three directions, [ X Y Z]^TRepresenting the coordinates of the auxiliary coordinate system in image space, and at represents the camera exposure delay.

Multi-view dense matching (9):

the dense matching (9) of the multi-view images is the core of the oblique photogrammetry technology, and the multi-view images have the characteristics of high ground resolution and large overlapping degree, but the data redundancy of the images is also caused; meanwhile, the flying height of the unmanned aerial vehicle is low, the flying posture of the unmanned aerial vehicle is unstable, so that the base height of the image is small, the change of the overlapping degree is obvious, the difficulty is brought to obtaining the homonymous point of the multi-view image, and how to quickly find the homonymous point in the multi-view image is the most important step of the multi-view image dense matching. The current mature algorithm is the SGM semi-global matching algorithm or the PMVS multi-view matching algorithm.

Construction of triangulated TIN (10):

the triangulation network (10) is mainly divided into two stages: firstly, point cloud data comprises constraint points to jointly establish a triangular network; and secondly, carrying out diagonal exchange by taking line elements obtained by image matching as constraint conditions, and adjusting each line segment in the triangulation network by using a local optimal process LOP to form the TIN triangulation network (10) with the constraint conditions.

Texture mapping (11):

the essence of the texture mapping (11) is to process the shot image to generate a texture image, establish the corresponding relation of two space points through a certain mathematical relation, wherein the two space points are the space point of the two-dimensional texture and the space point of the three-dimensional model respectively, and finally attach the texture image to the three-dimensional model to form a vivid three-dimensional model. Texture mapping can be divided into forward and reverse mapping according to the mapping direction.

After the image data is processed and modeled by a data platform, a series of models can be generated according to actual needs, such as: three-dimensional live-action models, DEMs, DSMs, DOMs, point cloud data, and the like.

After the three-dimensional live-action model is generated, format conversion is needed, common formats are OSGB and OBJ, and after the conversion is completed, the three-dimensional model can be imported into an application platform, such as: unity3D, Wish3D network, Xinxin earth PC, Altizure, etc., or further processing the three-dimensional model, and performing operations such as texture modification, mapping, model splicing, etc. on the model by using DP-Modeler, SVS, etc.

Step five: the three-dimensional real scene model and the product are directly applied (12):

as shown in fig. 2 and 3, the three-dimensional real scene model after flight can realize various functions and applications: (1) performing earth and stone square rechecking rapidly; (2) directly measuring the terrain data in the field; (3) carrying out on-site investigation analysis and scheme formulation on emergency rescue and disaster relief conditions; (4) flood risk assessment and simulation and disaster prevention scheme making; (5) analyzing buffer areas under different thresholds; (6) dynamic data management and present situation analysis; (7) other applications related to GIS.

Step (c): combining the three-dimensional digital model with BIM (13):

the point cloud data generated through the three-dimensional model can be imported into Civil3D, after a high-precision terrain curved surface is generated, roads and terraces are created according to design files, and therefore fast earth and stone calculation, various slope calculation and the like can be achieved.

Selecting BentleyLumenRT software to fuse a three-dimensional live-action model with Revit, and firstly solving the problem of multi-source heterogeneous data integration, namely how to integrate multiple formats of data obtained in different modes, mainly comprising the following steps: data structure, data type, application platform, coordinate system, elevation system, etc.; in particular, some problems caused by map projection transformation and coordinate transformation need to be considered, so that how to unify all standards before doing the project.

And programming by utilizing Dynamo, reading bridge design parameters, and placing a parameterization family, thereby solving the problem of short plates of Revit in bridge modeling at the present stage. After the bridge modeling is finished, the Revit model is converted into a format accepted by a corresponding platform, usually the formats are obj, skp, fbx, 3Dtiles and the like, and after the Revit model is imported into an operation platform, the fusion of the Revit project and the three-dimensional live-action model can be realized.

Step (c): and (4) carrying out precision inspection on the generated model after aviation.

In order to reduce the influence of projection difference on the accuracy of the image matching result, the position where the image control points are arranged should be 1-2cm away from the image boundary; the specific method for loading the corrected three-dimensional model into the ContextCaptureViewer software is as follows: the method comprises the following steps of respectively measuring each check point position for 5 times, taking coordinate values actually measured in the industry as true values, and calculating errors in the check point positions by combining the measured coordinate values of 5 times, wherein the purpose is to reduce the adverse effect of accidental errors on detection results, and the calculation formula is as follows:

in the formula:

m is the error in the checkpoint;

xi, yi are plane coordinate values acquired at the ith time on the three-dimensional model;

x and Y are measured check point values.

Example 2

The utility model provides an unmanned aerial vehicle oblique photography measurement system for road bridge construction field, utilize many sensors to data acquisition, the high-efficient quick massive data information that obtains from the angle of difference, software and hardware equipment selection (1), unmanned aerial vehicle oblique photography parameter is confirmed, unmanned aerial vehicle oblique photography course planning, aerial survey image aerial three calculation (8), many video dense matching (9), the structure (10) of triangle-shaped net TIN, texture mapping (11), three-dimensional live-action model and product direct application (12), three-dimensional digital model combines (13) with BIM.

Firstly, the type of the aircraft is selected, and the unmanned aerial vehicle (2) suitable for the conditions of a construction site is selected according to the brand and different types of the unmanned aerial vehicle (2) on the market. The unmanned aerial vehicle with stable flight, strong cruising ability, high pixel precision (4) and high positioning precision (4) is preferentially selected.

Since the image accuracy (4) is determined according to the planning model accuracy, the focal length (5) and the shooting distance (6) must be determined in order to achieve the predetermined image accuracy (4), as follows: the image accuracy (4) is the focal length (5) and the maximum size of the image is the sensor width, the shooting distance (6).

Before flight, the overall landform and ground objects of the project area are comprehensively analyzed, a flight route is formulated, and the aerial photographing height and the image overlapping degree are planned.

After the aviation flight is finished, the acquired image data is subjected to internal processing, and the data processing technology comprises main technical contents such as air route image air-to-three calculation (8), multi-view image dense matching (9), TIN triangulation network generation (10), texture mapping (11) and the like, so that real product data is finally obtained.

In order to reduce the influence of the projection difference on the accuracy of the image matching (9) result, the position where the image control points are arranged should be 1-2cm away from the image boundary.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.