CN110232523B

CN110232523B - BIM model light weight method

Info

Publication number: CN110232523B
Application number: CN201910514516.0A
Authority: CN
Inventors: 高志军; 张峻; 余少林; 张毅伟; 尹仕友
Original assignee: Shanghai Tongzhu Information Technology Co ltd
Current assignee: Shanghai Tongzhu Information Technology Co ltd
Priority date: 2019-06-14
Filing date: 2019-06-14
Publication date: 2023-06-09
Anticipated expiration: 2039-06-14
Also published as: CN110232523A

Abstract

A method for light weight of a BIM model, comprising: (1) Directly exporting the model to a database, and shortening export time; (2) Version management is uniformly carried out on the whole project, and each operation can be operated on a new version; (3) performing specialized operations on the model; (4) And the model is independently uploaded for modification, so that the model uploading efficiency is improved. The add version management section further includes a support rollback function, a view history version function, and a version comparison function. The added model is divided into professional function parts according to engineering specifications and habits. The invention saves the time for uploading and analyzing the BIM model; for the model which needs to be frequently modified, the model uploading efficiency can be greatly improved; on the other hand, the user can complete all the works by only setting the configuration information, so that the user experience is improved.

Description

BIM model light weight method

Technical Field

The invention belongs to the technical field of information, and relates to a building information model, in particular to a professional lightweight method for the building information model.

Background

BIM (Building Information Modeling) is a building information model, which is a technology for realizing the information management of the whole life cycle of a building by digitizing building information.

The BIM technology takes a digital information model as a basis, and integrates data materials of each stage of planning, designing, building, operating and the like into a 3D model, wherein the data materials comprise geometric information, professional information, building information and the like of model components.

Through the model, project information can be transferred and shared, and the model is used as a basis for cooperative work of all project participators, so that the participators can make reasonable decisions according to accurate and complete data, and the effects of improving working efficiency and working quality, reducing accidents, saving cost and shortening construction period are achieved.

The BIM technology has the functions of three-dimensional simulation, simulation test, information integration, shared collaboration and the like, can be effectively applied to project planning, collaborative design, collision inspection, performance analysis, construction simulation, cost and progress control and the like of the whole life cycle of a construction project, can effectively control design change, reduce reworking waste and construction period loss, completely preserve material pipeline information of building equipment, and has important significance for improving the fine management level of the project, enhancing pertinence of post-property management maintenance and the like.

In summary, the core of the BIM technique is to build a three-dimensional model and assign engineering information related to the model. The existing engineering projects are large in volume, and the super high-rise, super large foundation pit, large-span bridge tunnel and the like are of all-purpose, so that extremely high requirements on the graphic processing capability of a computer are provided.

To support a three-dimensional model with a huge running volume, a relatively heavy computer with a relatively high configuration needs to be purchased. However, this solution results in an increase in project cost on the one hand and is inconvenient for field personnel to conveniently work. In order to solve the problem, the BIM model light weight technology has been developed, namely, the model is compressed on the premise of not influencing the quality and the information integrity of the model, so that the model volume is greatly reduced, and the Web end and the mobile end can both support browsing of large complex professional models lightly and easily.

The existing BIM model light weight technology has the following defects:

(1) The conventional method needs to upload the model to a database and then to a platform, so that the operation is not simple and convenient, and the uploading speed is low;

(2) Model updates are cumbersome. Once the model is partially updated, the model is still required to be wholly reduced again for repeated work, and time is wasted;

(3) The method has no special export function and does not accord with the use habit of a user;

(4) The support capability for the bulk model is limited.

In order to solve the above problems, a new generation of BIM model lightweight technology is required to be proposed objectively.

Disclosure of Invention

Aiming at the defects of the existing BIM model light weight technology, the invention provides a new generation BIM model light weight method and system, which carry out function upgrading on the prior art, so that the light weight process is more convenient and more friendly to use, and comprises the following aspects:

(1) The step of deriving the model is reduced. Directly exporting a model such as a Revit model to a database, without midway conversion, uploading and downloading intermediate model files, and greatly shortening export time;

(2) Version management is added. Version management is uniformly carried out on the whole project, and each operation can be operated on a new version; a rollback function is supported, and a history version checking function and a version comparing function are checked;

(3) The professional function of the model is added. Performing professional operation on the model to ensure that the model is divided according to engineering specifications and habits;

(4) An increment uploading function is added. The model can be independently uploaded for modification without repeating the same model, and the model uploading efficiency is improved.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the invention comprises the following steps:

1. model upload configuration

(1) Platform items and projects corresponding to the model are selected, and the model is ensured to be uploaded to a correct position;

(2) Professional operation is carried out on the model, so that a professional tree can be automatically generated when the model is uploaded to the platform;

(3) Configuring elevation for the model, so that the model can automatically divide floors after being uploaded to a platform;

(4) A LOD (Levels of Detail) level of granularity may be set.

2. Deriving a model

Including two forms: (1) Deriving the dot-line-plane information of all the components, and then drawing by software such as Unity; (2) When the components are more or the model components are more complex, the huge amount of data exported to the client will result in excessive performance overhead, according to which the following optimizations are performed:

step 2-1: a model, such as a Revit model, is exported to the database. And (3) dividing the component into professions, then deriving dot line surface, attribute and material information of the Revit model according to the professions, then deriving elevation and axis network information to the database without distinguishing the professions, and finally deriving a material map of the Revit model and uploading the material map to a server. The flow is as follows:

step 2-1-1: deriving all cylinders in the model;

step 2-1-2: deriving all family instances derived from the family type (except for deriving only one);

steps 2-1-1 and 2-1-2 are optimized for components of the same shape and different positions.

For the cylinder, except for the position and the direction, the shape of the cylinder can be completely determined by only the length and the radius, and the small piece of the cylinder can be simply calculated and drawn, so that compared with the storage of the data of the small piece, the data volume can be greatly reduced by only storing the radius, the length and the center points at the two ends.

For the components generated from the same family type, only the point-line-plane information of the family type and the coordinate transformation of the family type to the components are needed to completely draw the components, and the data volume of the coordinate transformation is much smaller than that of the point-line-plane information of one component, so that the data volume can be greatly reduced.

If only one component is generated in a certain group type, and the component is derived according to the step 2-1-2, a transformation matrix is stored in addition to the point line surface information of the group type, and the data size is larger than that of directly storing the point line surface information of the component, so that the step 2-1-2 is not performed on the group type of only one component.

The dot-line information of the simple components is not less than the diameter plus the length of the cylinders, so that all the cylinders are processed preferentially (step 2-1-1), and then the step 2-1-2 is processed, thereby reducing the data quantity required to be transmitted by the network to the greatest extent.

Step 2-1-3: deriving components other than the components already derived in the steps 2-1-1 and 2-1-2;

step 2-1-4: deriving component properties;

step 2-1-5: leading out the elevation of the shaft net;

step 2-1-6: and (5) deriving materials and a map.

The method for reducing the BIM model size is as follows:

(1) For all components (family instances) derived from the same family type, only the grid information of the family type and the transformation matrix from the family type to the family instance are stored;

(2) For a cylindrical member, only the radius, length, starting point and ending point of the center line are saved, and grid information is not saved;

(3) And combining the materials of the components with the same color.

Step 2-2: the model is exported to a database, such as an ibox database, based on specialty and component size.

For each specialty, the components are partitioned into different database files in different proportions that account for the overall size. The compression format used is the compression format that decompresses fastest.

Each database file contains only one specialized component of the same size class.

The front end can download the corresponding professional files according to the order of the components from large to small according to the needs, and can download the model according to the size level of the components without distinguishing the profession.

3. Incremental uploading model

Step 3-1: loading a plug-in when tool software such as Revit is started, and monitoring modification of a model by a user;

step 3-2: when the Revit model file is saved, the user operation is permanently conducted to a database local to the user, such as an SQLite database;

for the case of modifying the halfway saved model file and then continuing editing

Step 3-3: matching the uploaded project according to the MD5 code of the model file;

step 3-4: and exporting the component added and deleted and modified by the user to the project matched in the step 3-3.

Storage mode of local data [ sqlite database, stored in separate file for convenient management ]:

all modifications to a certain file are put into the same GROUP and the order of the modifications is managed with version.

A main key: groupID > MD5 code

The last successfully uploaded MD5 code is obtained from the server during incremental updating, then is matched with a local database,

and taking the Group of the model file, merging all modifications after the version of the local database corresponding to the MD5 code on the server, and then uploading in an increment.

4. Front-end loading.

Step 4-1: downloading and decompressing the lz4 file to obtain an ibox database file;

step 4-2: internally loading ibox database files;

step 4-3: and extracting model grid information from the database for drawing.

Step 4-3-1: drawing the cylinder derived in the step 2-1-1, wherein the cylinder with the same specification is drawn only once;

step 4-3-2: drawing the group instance derived in the step 2-1-2, wherein the same component is drawn only once;

step 4-3-3: the model of the component derived in step 2-1-3 (not belonging to steps 4-3-1 and 4-3-2 above) is drawn, since this type of component has nothing in common with the other components, each component needs to be drawn separately once).

Aiming at one project, the models of the step 4-3-1 and the step 4-3-2 can be increased as much as possible, and the number of the models of the step 4-3-3 is reduced, so that a better performance effect can be obtained at the front end.

By adopting the technical scheme, the invention has the following beneficial effects:

(1) The BIM model can be directly stored in the platform database after being subjected to light weight treatment and is directly displayed at the front end, files with specific formats are not required to be exported for recompression and uploading, and time for uploading and analyzing the BIM model is saved. The user can complete all works by only setting the configuration information;

(2) Component information for front end display can be transmitted in a visual order from large to small, large components are displayed first, small components are loaded, and user experience is improved;

(3) For the uploaded model, an incremental uploading function is newly added. The user does not need to upload the whole model again, but only uploads the modified components, so that the model uploading efficiency can be greatly improved and the user experience can be improved for the model needing frequent modification;

(4) Version management is added, a rollback function is supported, and a history version viewing function and a version comparison function are provided.

Drawings

Fig. 1 is a flowchart of the upload setup of the present invention.

Fig. 2 is a flow chart of the derived model of the present invention.

FIG. 3 is a flow chart of the incremental upload model of the present invention.

FIG. 4 is a front-end loading flow diagram of the present invention.

Detailed Description

The invention is further described below with reference to the drawings and examples.

When the invention is applied, the method can be implemented according to the following steps:

1. model upload configuration

(4) The LOD refinement level may be set.

2. Deriving a model

Including two forms: (1) Deriving the dot line and plane information of all the components, and then drawing by Unity; (2) When the components are more or the model components are more complex, the huge amount of data exported to the client will result in excessive performance overhead, according to which the following optimizations are performed:

step 2-1: export the Revit model to the database. And (3) dividing the component into professions, then deriving dot line surface, attribute and material information of the Revit model according to the professions, then deriving elevation and axis network information to the database without distinguishing the professions, and finally deriving a material map of the Revit model and uploading the material map to a server. The flow is as follows:

step 2-1-1: deriving all cylinders in the model;

step 2-1-4: deriving component properties;

step 2-1-5: leading out the elevation of the shaft net;

step 2-1-6: and (5) deriving materials and a map.

The method for reducing the BIM model size is as follows:

(3) And combining the materials of the components with the same color.

Step 2-2: models are exported to the ibox database based on specialty and component size.

For each specialty, the components are partitioned into different database files in different proportions that account for the overall size. Because the derived model loads the most intuitive user experience of the speed impression when displayed on a browser or cell phone, the compression format employed is the one that decompresses the fastest. Compression is performed using the Lz4 format.

The following are test data from the Quick Benchmark referring to https:// catchchanger. First-world. Info Gzip vs Bzip2 vs LZMA vs XZ vs LZ vs LZO

Actual example of export:

taking a foundation pit engineering in the Shanghai as an example (the following data are actual data, and are derived when LOD grade is 12)

The comparison effect before and after the optimization of the step 2-1-1 is added is as follows:

description:

1. the reason for optimizing the number of faces and the number of vertices is as follows: the cylindrical triangulation accuracy (how many facets are substituted for circles) is independent of the LOD of the model itself, so there is less;

2. load average time optimization reasons: the optimization of the step 2-1-1 and the optimization of the file size are dual functions;

3. the individual loading time optimization reasons: the optimization of the step 2-1-1 just draws one cylinder and the other copies.

Taking a subway station in the Shanghai as an example (the following data are actual data, and are derived when LOD grade is 12):

the comparison of the effects before and after the addition of the optimization of the previous step 2-1-2 is as follows:

	without optimisation	Optimization of addition of 2-1-2	Optimization rate
				Number of faces	7.20M	7.20M	0％
Top count	6.00M	6.00M	0％
				Average time of 5 times loading (downloading network speed 3.5M)	0:42	0:27	36％
File total size (M)	411.10M	247.49M	40％
				Independent loading time(s) irrespective of download	6.9s	4.5s	35％

Description:

1. 2-1-2 does not include optimization of face number and top number;

2. load average time optimization reasons: the optimization of the step 2-1-2 and the optimization of the file size have double functions;

3. file total size optimization reasons: the optimization of the step 2-1-2 only saves the triangular patch information of the parent body, and other examples only save the transformation matrix;

4. the individual loading time optimization reasons: the optimization of the previous step 2-1-2, the building block only draws one, the other copies.

The export flow is illustrated as follows: there is a conference room model comprising 1 long conference table, 12 chairs, televisions, air conditioners, whiteboards.

4 walls, roof, floor, round posts 2.

The subtractive modeling is applied to this model as follows:

the client may display the components of the specified specialty, or mask the components of the specified specialty:

wall, roof, floor, column allocation to construction professions

Other assignments to article professions

Derivation of

Step 2-1-1 derivation of 2 cylinders

Step 2-1-2 derive the family type of chair and transform matrix to 12 chairs

Step 2-1-3 derivation of other Components

Step 2-1-4-2-1-6, deriving component attribute, material quality, mapping and shaft net mark height

Preparation before transmission

The derived dotted planes are classified by the bounding box size of the component,

first stage: walls, roofs, floors, posts

Second stage: conference table

Third stage: chair, television and air conditioner

Fourth stage: white board

Exporting data to ibox database by specialty and size

Structure_1: wall, roof, floor

Structure_2: column

Item_2: conference table

Item_3: chair, television and air conditioner

Item_4: white board

Transmission & display

All professions are loaded by the client by default, and the transmission sequence is as follows: structure _1, item _2, item _3, item _4,

when the web pages are loaded, the web pages are sequentially loaded according to the transmission sequence, rooms are drawn firstly on visual effect, then columns and conference tables are drawn, and then other components such as chairs are drawn.

For the GIS client, when the initial state lens is far away, data with the size level of 1 is requested [ structure_1 ], and model data with the corresponding size is requested from the server along with the lens being zoomed in [ structure_2, object_2 … … ]

3. Incremental uploading model

Step 3-1: plug-in is loaded during Revit starting and is used for monitoring

User modification of the model;

record the operation of each component [ add, modify, delete ]

Considering the burden of the client, the operation history on the member is not recorded, and only the final result is recorded. If a component is added and then modified, the end result is still an increase.

For each operation that the UNDO operation is not recorded, the UNDO operation is uniformly recorded,

if the component operating as UNDO still exists during storage, the component is used as a modifying operation, and if the component does not exist, the component is used as a deleting operation.

Step 3-2: when the Revit model file is stored, the user operation is permanently carried out on the SQLite database local to the user;

A main key: groupID > MD5 code

Illustrating: opening the model, and creating a GroupID [ XX ] because the local database has no data of related MD5 codes

Modifying the model file, wherein the MD5 code is A1 when the model is stored, the database stores a piece of XX-A1-1 data, and 1 is a version number.

And uploading the model file, wherein the uploading MD5 code stored by the server is A1.

The model is opened again, records exist in a local database, the Group is XX, the record can be determined, the record is modified, the MD5 code is A2 when the model is stored, and the database stores a piece of XX-A2-2 data.

Continuing editing, storing the MD5 code as B1, and storing the XX-B1-3 data in the database.

Incremental uploading is performed, the MD5 code on the server is A1, the corresponding Group is XX, and the version is 1, so that in the modification of Group XX, all modifications of version >1 need to be synchronized, which is to combine the operations in version order, and then incremental uploading is performed on the modified components.

4. Front-end loading.

step 4-2: internally loading ibox database files;

step 4-3: and extracting model grid information from the database for drawing.

Step 4-3-1: drawing the cylinder derived in the step 2-1-1 (the members of the same class have the same diameter and length, and dynamic batch is triggered when drawing in units), and drawing the cylinder with the same specification only once;

step 4-3-2: drawing the group instance derived in the step 2-1-2 (the appearance shapes of the components of the class are the same, and the components of the class with the same mesh are drawn only once because GPUInstance is started in the unity);

By processing model data into a data structure that Unity can map in advance and making a series of optimizations targeted, an oversized model (on the order of hundreds of millions of patches) can be supported.

The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments. Those skilled in the art will appreciate that, in light of the principles of the present invention, improvements and modifications can be made without departing from the scope of the invention.

Claims

1. A method for light weight of a BIM model, comprising:

(1) Reducing the step of deriving the model

Directly exporting the model to a database, and shortening export time;

(2) Increasing version management

Version management is uniformly carried out on the whole project, and each operation can be operated on a new version;

(3) Adding professional functions of models

Performing professional operation on the model;

(4) Adding an incremental upload function

The model is independently uploaded for modification, so that the model uploading efficiency is improved;

the derived model includes two forms: (1) Deriving the dot line and plane information of all the components, and then drawing by Unity; (2) When the components are more or the model components are more complex, the huge amount of data exported to the client will result in excessive performance overhead, according to which the following optimizations are performed:

step 2-1: exporting the Revit model to a database; dividing the components into professions, then deriving dot line surface, attribute and material information of the Revit model according to the professions, then deriving elevation and axis network information to the database without distinguishing the professions, and finally deriving a material map of the Revit model and uploading the material map to a server; the flow is as follows:

step 2-1-1: deriving all cylinders in the model;

step 2-1-2: deriving all family instances derived from the family type except for only one derived from the family type;

steps 2-1-1 and 2-1-2 are optimized for components of the same shape and different positions;

for the cylinder, except for the position and the direction, the shape of the cylinder can be completely determined by only the length and the radius, and the small patches of the cylinder can be simply calculated and drawn, so that compared with the storage of the data of the small patches, the data volume can be greatly reduced by only storing the radius, the length and the center points at the two ends;

for the components generated from the same family type, the components can be completely drawn only by the point-line-plane information of the family type and the coordinate transformation from the family type to the components, and the data volume of the coordinate transformation is much smaller than that of the point-line-plane information of one component, so that the data volume can be greatly reduced;

if only one component is generated in a certain group type, and the component is derived according to the step 2-1-2, a transformation matrix is stored besides the point line and plane information of the group type, and compared with the point line and plane information of the component, the data size is larger, so that the step 2-1-2 is not performed on the group type of only one component;

the dot line and plane information of the simple components is not less than the diameter plus the length of the cylinder, so that all the cylinders are processed preferentially, namely, the step 2-1-1 is processed, and then the step 2-1-2 is processed, so that the data quantity required to be transmitted by a network can be reduced to the greatest extent;

step 2-1-4: deriving component properties;

step 2-1-5: leading out the elevation of the shaft net;

step 2-1-6: deriving a material and a map;

the method for reducing the BIM model size is as follows:

(1) For all members derived from the same family type, namely family examples, only the grid information of the family type and the transformation matrix from the family type to the family examples are stored;

(3) Combining the materials of the components with the same color;

2. The method for light weight of a BIM model according to claim 1, wherein:

the incremental version management also includes a support rollback function, a view history version function, and a version comparison function.

3. The method for light weight of a BIM model according to claim 1, wherein:

the added models are divided according to engineering specifications and habits in the professional functions.

4. The method for light weight of a BIM model according to claim 1, wherein performing the model upload configuration includes:

(A1) Platform items and projects corresponding to the model are selected, and the model is ensured to be uploaded to a correct position;

(A2) Professional operation is carried out on the model, so that a professional tree can be automatically generated when the model is uploaded to the platform;

(A3) Configuring elevation for the model, so that the model can automatically divide floors after being uploaded to a platform;

(A4) The LOD refinement level is set.

5. The method for light weight of a BIM model according to claim 1, wherein:

for each specialty, the components are partitioned into different database files in different proportions that account for the overall size.

6. The method for light weight of a BIM model according to claim 1, wherein: compression is performed using the Lz4 format.

7. The method for light weight of a BIM model according to claim 1, wherein: each database file contains only one specialized component of the same size class.

8. The method for light weight of a BIM model according to claim 1, wherein: the front end downloads the corresponding professional files according to the order of the components from large to small according to the needs, or does not distinguish the professional downloading model according to the size grade of the components.

9. The method for light weight of a BIM model according to claim 1, wherein the incremental upload function includes the steps of:

step 3-1: loading a plug-in when the tool software is started, and monitoring the modification of a model by a user;

step 3-2: when the model file is saved, the user operation is permanently carried out to a database local to the user;

in the case where the model file is saved halfway in the modification and then editing is continued, the following is performed,

step 3-4: and (3) exporting the modified components added and deleted by the user to the project matched in the step 3-3.

10. The method for light weight of a BIM model according to claim 9, wherein:

the storage of the local data adopts a sqlite database, and the local data is stored in a separate file for convenient management;

all modifications to a certain file are put into the same GROUP, and the order of the modifications is managed by version;

a main key: groupID > MD5 code

Obtaining the MD5 code successfully uploaded last time from a server during incremental updating, and then matching with a local database;

11. The method of BIM model weight reduction of claim 1, further comprising front-end loading, the front-end loading comprising:

step 4-1: downloading and decompressing the file to obtain a database file;

step 4-2: internally loading the database file;

step 4-3: and extracting model grid information from the database for drawing.

12. The method of BIM model weight reduction according to claim 11, wherein step 4-3 includes:

step 4-3-1: drawing the cylinder derived in the step 2-1-1, and drawing the cylinder with the same specification once;

step 4-3-2: drawing the group instance derived in the step 2-1-2, wherein the same component is drawn once;

step 4-3-3: drawing the component derived in the step 2-1-3.

13. The method for light weight of a BIM model according to claim 12, wherein: for one project, the models of the step 4-3-1 and the step 4-3-2 are increased as much as possible, and the number of the models of the step 4-3-3 is reduced.