1. A production method of a lightweight real-scene three-dimensional model integrated with a BIM design platform is characterized by comprising the following steps:

step S1) carrying out lightweight processing on the live-action three-dimensional model;

step S2) carrying out comprehensive attribute quality evaluation on the lightweight live-action three-dimensional model;

step S3) fine repair is carried out on municipal facilities of the live-action three-dimensional model;

step S4) the lightweight real-scene three-dimensional model is blended into the 3D EXPERIENCE BIM design platform.

2. The method for producing a lightweight realistic three-dimensional model incorporated into a BIM design platform as claimed in claim 1, wherein in step S1, the lightweight processing is performed by using a QEM lightweight algorithm and an LOD level method respectively according to the characteristics of the realistic three-dimensional model data format itself, and an optimal lightweight coefficient is determined.

3. The method for producing a light-weight live-action three-dimensional model integrated with a BIM design platform as claimed in claim 2, wherein the QEM algorithm is adopted to carry out light-weight processing on FBX format data of the live-action three-dimensional model, C + + is adopted as a programming language, Visual Studio2017 is adopted as a development tool, the method is operated under a Windows system, and the FBX format data comprises model files, texture mapping files and model formats of texture pictures.

4. The method for producing a light-weight live-action three-dimensional model integrated with a BIM design platform as claimed in claim 2, wherein the LOD level method comprises the steps of determining the resource allocation of object rendering according to the positions and the importance of the nodes of the object model in the display environment, reducing the number of faces and the detail of non-important objects, and performing light-weight processing on the large-scene live-action three-dimensional model data in a regional and hierarchical manner by taking the characteristic of the tower level with characters in OSGB and 3MX formats as an entry point according to technical reports.

5. The method for producing a light-weight live-action three-dimensional model integrated into a BIM design platform as claimed in claim 2, wherein in step S2, the comprehensive attribute quality assessment includes visual effect assessment and position accuracy assessment, the visual effect assessment includes scene effect and expression fineness, and the position accuracy assessment includes plane accuracy and height accuracy.

6. The method for producing a lightweight live-action three-dimensional model integrated with a BIM design platform as claimed in claim 5, wherein after the visual effect evaluation is passed, the position accuracy evaluation is performed, and if the comprehensive attribute quality evaluation is not passed, the lightweight coefficient is adjusted, and the step S1 is performed again;

if the position accuracy evaluation is passed, the process proceeds to step S3; if the position accuracy evaluation fails, the weight reduction coefficient is adjusted, and step S1 is executed again.

7. The method of claim 6, wherein in the position accuracy evaluation stage, the coordinates of the same point under different weight reduction scale coefficients are compared, and the error caused by the model weight reduction is evaluated, so as to complete the plane position accuracy evaluation of the weight reduction models with different coefficients, and the weight reduction models with obvious texture and data amount variation are selected, the plane coordinates of each check point are picked up, the error m in the point plane is calculated,

and delta is a true error, namely the difference between the coordinate value of each check point under different coefficients and the coordinate value of the original model, and n is the number of the check points.

8. The method for producing a lightweight real-world three-dimensional model integrated with a BIM design platform as claimed in claim 1, wherein in step S3, a municipal facility standard component model library is established by means of a 3D EXPERIENCE BIM forward design platform, municipal facilities distorted in the real-world three-dimensional model are finely repaired, and in the process of establishing the municipal facility standard component model library, the component library is divided into ten types of elements, namely buildings, water systems, traffic, boundaries, terrain, landforms, vegetation, pipelines, palisades and independent ground objects, and is decomposed into two parts, namely geometric features and texture features.

9. The method for producing a lightweight realistic three-dimensional model integrated with a BIM design platform as claimed in claim 1, wherein in step S4, the lightweight model file and the sticker file are merged and rendered, the sticker file is attached to the model file according to the sticker information, the merged lightweight realistic three-dimensional model data is imported into the 3D EXPERIENCE design platform, the lightweight realistic model is integrated with the BIM design platform 3D EXPERIENCE, the design, display, comparison and modification are performed in the BIM design platform, the multi-source model spatial coordinate system is set, and the design model is integrated with the real scene.

Background

With the rapid advance of new infrastructure such as smart cities, twin cities, big data, internet of things, multi-test integration and the like, Building Information Models (BIM) and real-scene three-dimensional models are widely concerned by the industry as main sources of basic data of a space geographic Information framework.

BIM technology and unmanned aerial vehicle oblique photography measurement technique play an important role in novel infrastructure application such as wisdom city, unmanned aerial vehicle as the important example technique in the building engineering application. In each stage of the full life cycle of the building, the BIM technology is combined with a full-texture and full-element live-action three-dimensional model, so that the conversion of the industry idea, the reduction of the cost and the improvement of the efficiency are brought.

In the BIM planning and designing stage, a real three-dimensional model of a project area is often utilized to provide real and accurate three-dimensional basic data for BIM design, and scheme design and scheme comparison are rapidly completed through a BIM technology. However, due to the limitations of the characteristics of the live-action three-dimensional model and the performance of the BIM design platform, the live-action three-dimensional model cannot be deeply applied to the BIM planning and designing stage at present.

The existing unmanned aerial vehicle oblique photogrammetry technology and three-dimensional modeling software produce a live-action three-dimensional model, the data volume of the live-action three-dimensional model is huge, the storage formats of model data are various, and there are distortions such as bugs, adhesion, suspended matters and the like, and the existing model restoration software is difficult to realize the quick and fine restoration of municipal facilities.

Disclosure of Invention

The invention aims to provide a production method of a lightweight live-action three-dimensional model integrated with a BIM design platform, which compresses the data volume of the live-action three-dimensional model to the maximum extent on the premise of meeting visual effect and geometric accuracy, is integrated with the BIM design platform and assists in forward design.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a production method of a lightweight real-scene three-dimensional model integrated with a BIM design platform is characterized by comprising the following steps:

step S1) carrying out lightweight processing on the live-action three-dimensional model;

step S2) carrying out comprehensive attribute quality evaluation on the lightweight live-action three-dimensional model;

step S3) fine repair is carried out on municipal facilities of the live-action three-dimensional model;

step S4) the lightweight real-scene three-dimensional model is merged into the 3D EXPERIENCE design platform.

Further, in step S1, according to the characteristics of the data format itself, a QEM lightweight algorithm and an LOD hierarchy method are respectively used to perform lightweight processing, and an optimal lightweight coefficient is determined.

Further, carrying out lightweight processing on FBX format data of the live-action three-dimensional model by adopting a QEM algorithm, adopting C + + as a programming language, using Visual Studio2017 as a development tool, and operating under a Windows system, wherein the FBX format data comprises model files, texture mapping files and model formats of texture pictures.

Further, the LOD level method comprises the steps of determining resource allocation of object rendering according to the positions and the importance of the nodes of the object model in the display environment, reducing the number of faces and the detail of non-important objects, and reducing the live-action three-dimensional model data of the large scene step by taking the characteristic of the word tower level of the OSGB and the 3MX format as an entry point according to a technical report.

Further, in the step S2, the integrated attribute quality assessment includes a visual effect assessment whose contents include a scene effect and expression fineness, and a position precision assessment whose contents include a plane coordinate value precision and a height value precision.

Further, after the visual effect evaluation is passed, the position accuracy evaluation is performed again, and if the comprehensive quality evaluation is not passed, the lightweight coefficient is adjusted, and the step S1 is performed again;

if the position accuracy evaluation is passed, the process proceeds to step S3; if the position accuracy evaluation fails, the weight reduction coefficient is adjusted, and step S1 is executed again.

Further, in the position precision evaluation stage, a lightweight model with obvious texture and data volume change is selected, the plane coordinates of each check point are picked up, the error m in the point location plane is calculated,

and delta is a true error, namely the difference between the coordinate value of each check point under different coefficients and the coordinate value of the original model, and n is the number of the check points.

Further, in the step S3, a standard component model library of municipal facilities is established by means of a BIM design platform, the municipal facilities distorted in the real-scene three-dimensional model are refined and repaired, and in the process of establishing the standard component model library of municipal facilities, the component library is divided into ten types of elements, namely buildings, water systems, traffic, borders, terrains, geomorphology, vegetation, pipelines, palisades and independent terrains, and is decomposed into two parts, namely geometric features and texture features.

Further, in step S4, the lightweight real-scene model is fused into the BIM design platform 3D EXPERIENCE, scheme design, display, comparison, and modification are performed in the BIM design platform, a multi-source model spatial coordinate system is set, and the design model and the real-scene are fused.

The invention discloses a method for finely repairing municipal facilities in a real-scene three-dimensional model by taking BIM modeling software as a repairing platform, which takes service BIM design as a core, aims to integrate BIM design resources to the maximum extent, establishes a general municipal facility component model library, and completes the fine repairing of the real-scene three-dimensional model and simultaneously serves the BIM design.

According to the method, the model file and the map file are merged and rendered, the map file is attached to the model file according to the map information, and the merged lightweight real-scene three-dimensional model data is imported into a 3D EXPERIENCE platform, so that the working efficiency is improved, external space reference is provided for designers, and the problems of unreasonable space planning, model space position information loss and the like are solved.

Scheme design, display, comparison and modification are directly carried out in the BIM design platform, and the problems that third-party software is checked and multiple platforms are repeatedly compared and modified are solved. And the fusion of a design model and a field scene is realized by setting a multi-source model space coordinate system.

The fusion application of the multi-source model expands the application depth and the application range of the real three-dimensional model in the BIM design stage, and fills the blank that the lightweight real three-dimensional model is fused into the BIM design platform.

Drawings

FIG. 1 is a flow chart of the quality evaluation work of the lightweight live-action three-dimensional model of the invention;

FIG. 2 is a schematic view of a model of an individual feature of the present invention;

FIG. 3 is a schematic diagram of the fine repair of local road facilities according to the present invention;

FIG. 4 is a schematic view of a combination of a lightweight real-world model, a high-voltage component model and a BIM model according to the present invention

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. 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.

The invention discloses a method for producing a lightweight real-scene three-dimensional model integrated with a BIM design platform, which comprises the following steps:

step S1) carrying out lightweight processing on the live-action three-dimensional model;

step S2), evaluating the comprehensive attribute quality of the lightweight live-action three-dimensional model;

step S3) fine repair of the municipal facilities of the live-action three-dimensional model;

step S4) the lightweight real-scene three-dimensional model is blended into the 3D EXPERIENCE design platform.

Further, in step S1, the live-action three-dimensional model weight reduction process includes: taking general formats of FBX and OSGB as examples, respectively adopting QEM and LOD hierarchical methods to carry out lightweight processing according to the characteristics of a data format, and determining an optimal lightweight coefficient on the premise of considering texture effect, position precision and data quantity.

And carrying out lightweight processing on the live-action three-dimensional model by adopting a QEM algorithm, adopting C + + as a programming language, using Visual Studio2017 as a development tool, operating under a Windows system, and aiming at the FBX format in the live-action three-dimensional model data, wherein the data comprises model files, texture mapping files and the model format of texture pictures.

The OSGB and S3C format data in the live-action three-dimensional model adopts an LOD hierarchical structure, the LOD technology determines the resource allocation of object rendering according to the position and the importance of the node of the object model in the display environment, and reduces the number of faces and the detail of non-important objects, so that high-efficiency rendering operation is obtained, the technical report takes the characteristic of the OSGB and 3MX format with a word tower level as an entry point, the large-scene live-action three-dimensional model data is reduced step by step, and the aim of light weight processing of the live-action three-dimensional model data is fulfilled.

During implementation, the weight reduction coefficient is specifically that, aiming at the live-action three-dimensional model data which is lightened by using the QEM algorithm, the reduced number of triangular mesh surfaces accounts for the proportion of the mesh surfaces of the original model data in the process of weight reduction.

Such as: the initial model consists of 100000 grid surfaces, 40000 grid surfaces are reduced during light weight treatment, and the light weight coefficient is 40%.

Specifically, for the LOD level algorithm light-weighted live-action three-dimensional model, LOD level data is extracted in the light-weighting process, and the maximum number in the level coefficient in the light-weighted live-action three-dimensional model data is defined as the LOD level of the light-weighted data.

Such as: the initial model is composed of ten levels of LOD15 and LOD16 … LOD 24 data, in the process of weight reduction, six levels of LOD15 and LOD16 … LOD20 of all the data are extracted, the maximum level coefficient is 20, and the weight reduction model is defined as the level coefficient being LOD 20.

And if the lightweight live-action three-dimensional model cannot meet the requirements of visual effect or geometric accuracy, adjusting in the following way, and performing comprehensive attribute quality evaluation again after adjusting.

1) Aiming at the QEM algorithm: the weight reduction coefficient is adjusted by controlling and reducing the number of the triangular mesh surfaces. If the grid surface of 40000 tablets cannot meet the requirement, 20000 tablets are reduced, and the lightweight coefficient is 20%.

2) For LOD level coefficients: by extracting the hierarchy of the model data to adjust, LOD15, LOD16 … LOD19, and having a maximum hierarchy coefficient of 19, the lightweight model is defined as having a hierarchy coefficient of LOD19, i.e., the coefficient is adjusted to LOD 19.

Further, in the step S2, a light-weight live-action three-dimensional model satisfying design requirements is provided for different requirements of each stage of engineering design in the construction field with the BIM design based on the live-action three-dimensional model as a guide. And considering both the texture quality and the plane position precision of the model, analyzing and researching the real-scene three-dimensional model data lightweight efficiency and the quality evaluation method of the lightweight model result through a comparison test.

The method is characterized in that service BIM design is used as guidance, quality evaluation factors of a lightweight live-action three-dimensional model are refined according to specific requirements of different engineering design stages, the lightweight live-action three-dimensional model provides ground feature and landform references for designers in a design scheme feasibility research stage, and a BIM design scheme is embedded on the lightweight live-action three-dimensional model, so that the problems of unreasonable space planning, no external reference for a model monomer and the like can be avoided, and the method is mainly used for displaying, comparing and modifying the BIM scheme; therefore, the scene effect and the expression fineness are used as the primary factors for quality evaluation of the lightweight real-scene three-dimensional model.

In the initial design and construction design stages, details of various buildings are designed in detail, and the measurable realistic three-dimensional model can provide spatial information such as coordinates, distances, areas, volumes and the like for designers, and the geometric position precision of the lightweight realistic three-dimensional model needs to be evaluated in quality in the stage.

According to different requirements of a design stage, the quality evaluation factors of the lightweight model are divided into two stages of model visual effect evaluation and position precision evaluation, the quality evaluation is carried out on the lightweight processed real scene three-dimensional model according to 4 factors of scene effect, expression fineness, plane precision and elevation precision, and the quality evaluation factors and the method are shown in table 1.

TABLE 1 quality assessment factor and method

The quality evaluation of the lightweight live-action three-dimensional model is mainly checked by adopting an internal human-computer interaction method. The method comprises the steps of manually checking in three-dimensional model browsing software, fixing a browsing visual angle according to an aerial photographing angle of an unmanned aerial vehicle, stretching to a height with a consistent resolution ratio to check the comprehensive attributes of the model, evaluating the obvious problems of leaks, deformation, flower formation and the like by adopting a defect deduction method, manually selecting a plurality of checking points on the model to evaluate the position accuracy of the model after the evaluation of the visual effect is qualified, and specifically evaluating the flow shown in figure 1.

The method for evaluating the comprehensive attribute quality of the lightweight live-action three-dimensional model comprises the following specific steps:

step S21) weighting;

under the condition that the lightweight live-action three-dimensional model is not unified and formally subjected to quality evaluation standards and standard references, the weight of each quality evaluation factor is set by adopting a subjective valuation method, the scene effect and the expression fineness in the quality evaluation factors jointly reflect the visual effect of the lightweight live-action three-dimensional model, the scene effect emphasizes the integral integrity of the model and the expression fineness emphasizes the resolution of ground objects, the integral expression integrity of the regional target model is emphasized in the feasibility research stage of the design scheme, so the scene effect weight is set to be 0.2, the expression fineness weight is set to be 0.1, the position precision requirement of a designer on the target region model data is higher in the primary design stage and the construction drawing design stage, the plane precision weight is set to be 0.5, and the elevation precision weight is set to be 0.2.

The lightweight processing can cause the change of the geometric structure and the texture structure of the real-scene three-dimensional model, the phenomena of leak and model resolution reduction occur, in the evaluation of visual effect, the calculation of 1: 500. 1: 1000. 1: and the model precision corresponding to the 2000 scale is used for measuring the size of the leakage hole of the lightweight live-action three-dimensional model and the resolution of the model data.

The plane position precision value and the elevation precision value are divided according to corresponding technical specifications or design requirements, and the quality evaluation factor grading and deduction detailed rules are shown in a table 2.

TABLE 2 quality assessment factor Classification and deduction criteria

The specific meanings of the parameters in table 2 are as follows:

(1) the scene effect is determined by the degree and the quantity of the model loopholes, and d is the maximum diameter of a single loophole;

(2) the fineness of expression is based on the minimum resolution of the model, M_aFor model precision, the smaller the numerical value is, the higher the model resolution is;

(3)M_0(x，y)、M_0(h)absolute values of errors in a plane and errors in an elevation of the model product are respectively required by specifications or corresponding technical documents;

(4)M_(x，y)、M_(h)the absolute values of the errors in the plane and the errors in the elevation of the check point on the model are calculated according to the following formula:

in the formula, Δ is a true error, i.e., a difference between the coordinate value of each inspection point at a different LOD level and the real measurement coordinate value. n is the number of check points.

The diameter of the leak, the number of leaks, the model precision and the spatial coordinates of the check points are acquired manually, generally t is 1, and the difficulty categories of the division of the interior industry are adjusted according to the relief of the terrain, the areas of roads, water systems, buildings and industrial areas and the complexity of soil vegetation by referring to 1: 2000-1: 500 photogrammetry.

Step S22) manual inspection;

the lightweight live-action three-dimensional model adopts an internal human-computer interaction mode for inspection, the view angle is fixedly browsed in browsing software by referring to the unmanned aerial vehicle aerial photographing angle, and the height of the scene and the fineness of ground objects are inspected by stretching to the height of the consistent resolution ratio. And (3) mainly checking the scene effect and the fineness expression aspect of the area where the BIM design scheme is located, such as whether the quality problems caused by light weight treatment exist on two sides of a main road, high-rise buildings and key areas specified by designers or not.

Step S23);

the quality factor scoring method comprises presetting the quality factor score to 100, deducting the errors and omissions appearing in the corresponding quality factors one by one according to the requirement, specifically as follows,

in the formula: s₁Scoring a quality factor; a is₁、a₂、a₃、a₄、a₅Each representing the corresponding A, B, C, D, E number in the factor.

Under different levels, the resolution value of the same area is taken to replace the integral resolution of the model, M_aThe value of (A) is unique, and the number of the values is 1; m of model checkpoints at different levels_(x，y)、M_(h)And the value of M is unique, and the numerical value of M is 1.

And calculating the product quality score by adopting a weighted average method according to the unit product quality score, wherein the calculation formula of S is as follows:

in the formula: s, S_1iScoring the product quality and quality factor; p_iThe weight of the corresponding quality factor; n is the number of quality factors contained in the product。

And (3) evaluating the product quality: and (4) carrying out quality evaluation on the lightweight real-scene three-dimensional model data by taking the implementation range as a unit product. And if the quality evaluation factor score is less than 60 points, the product is unqualified. The A-type miscarriage appears as an unqualified product.

Step S24) checking the position precision;

in the product quality evaluation process, the quality factor scores of the plane precision and the elevation precision are calculated respectively, and the position precision cannot be measured accurately. By M_)x，y)、M_(h)Calculating the position precision M of the model, calculating the score value of M, and judging whether the position precision M is qualified or not;

further, in said step S3, for the repair of a large number of similar, size standard municipal facilities, the subject is to construct a component model library within the BIM design platform for the repair of standard municipal facility distortion. The problem that a standard ground object in a live-action three-dimensional model cannot be accurately modeled is solved, a foundation is provided for designers to quickly construct the BIM, and the aims of seamless connection and function integration of model restoration and BIM core modeling software are fulfilled.

A standard component model library of the municipal facilities is established by depending on a BIM design platform, the municipal facilities distorted in the live-action three-dimensional model are subjected to fine repair, meanwhile, components in the standard component model library can be called in the design process to complete BIM design, the library is multipurpose, the platform is universal, and the subsequent fusion application of the live-action three-dimensional model and the BIM is facilitated.

In the process of constructing the municipal facility standard component model library, in order to avoid component omission, a subject refers to a drawing element system of a two-dimensional map, the component library is divided into ten elements such as buildings, water systems, traffic, boundaries, terrains, landforms, vegetation, pipelines, palisade grids, independent objects and the like, and the ten elements are decomposed into two parts of geometric features and texture features according to the specific characteristics of the elements.

The independent ground object model library is used for describing objects which can be abstracted into one point and are independent in space position, such as street lamps, garbage cans, mail boxes, traffic lights, bulletin boards and the like. Most independent objects have the same local geometric outline (such as roofs, balconies and the like) and are different only in geometric dimension, and urban infrastructures (such as street lamps, garbage bins, traffic lights and the like) also have the same shape.

The method is characterized in that a municipal construction component model is constructed, BIM designers can directly use the model only by simple parameter adjustment, so that the modeling workload is reduced, the modeling efficiency is improved, and operations such as geometric modeling, editing and the like are performed in a BIM design platform by taking municipal road facility components as an example, as shown in figure 2.

Adjusting the component parameters of the municipal facilities by taking BIM design software 3D MAX and Rhino as a repair platform of the real-scene three-dimensional model, and performing fine repair on distorted municipal facilities by using a standard component model, as shown in FIG. 3; the high voltage electric tower is repaired as shown in figure 4.

The finely repaired real-scene three-dimensional model is used as an important source of basic data, a large number of ground objects in the urban three-dimensional model need to be repaired, and various ground objects such as well covers, line towers and the like can provide attribute and geometric information of underground and overground pipelines for designers, and can be selectively avoided at the beginning of scheme design.

Further, in step S4, the light-weight live-action model is integrated into the BIM design platform 3D EXPERIENCE without affecting the visual effect and the spatial geometric accuracy, and when the light-weight coefficient is 40%, the introduction time can be saved by about 30%.

In order to compress the time for importing the live-action three-dimensional model data into the 3D EXPERIENCE platform, the lightweight live-action three-dimensional model is imported into the platform by the project on the premise of not influencing the visual effect and the geometric precision.

The 3D EXPERIENCE cannot read the model file and the map file respectively, so the model file and the map file are merged and rendered, the map file is attached to the model file according to the map information, and the merged lightweight live-action three-dimensional model data is imported on a 3D EXPERIENCE platform.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.