WO2024214841A1

WO2024214841A1 - Method for storing three-dimensional model information, and device therefor

Info

Publication number: WO2024214841A1
Application number: PCT/KR2023/004954
Authority: WO
Inventors: 이봉준; 편말순; 이용혁
Original assignee: 주식회사 씨엠월드
Priority date: 2023-04-12
Filing date: 2023-04-12
Publication date: 2024-10-17

Abstract

A method for storing three-dimensional (3D) model information, and a device therefor are disclosed. The 3D model storage device repetitively performs the steps of: reducing, according to a pre-defined Nth (N is a natural number greater than or equal to 1) simplification ratio, the number of pieces of graphics data of a 3D model indicating at least one object in a certain space, so as to generate an Nth simplified model, storing the Nth simplified model in a database, and generating Nth simplified models in the pre-defined number (N) of simplification ratios; and storing same in the database.

Description

Method for storing 3D model information and device thereof

An embodiment of the present invention relates to a method and a device for storing a three-dimensional model representing an object in a certain space, and more specifically, to a method and a device for storing a three-dimensional model representing various facilities above ground or underground.

In general, 3D model information for aboveground or underground facilities is composed of 3D mesh data. 3D mesh data represents various objects existing in space (e.g., buildings, underground facilities, roads, sewer pipes, etc.) by defining them as a set of shapes consisting of vertices and line segments connecting the vertices.

For example, 3D model information for the management of underground utilities includes object-based shape information, attribute information, etc., data generated according to the entire life cycle of the facility, so the 3D model information has a large size. This large-scale 3D model information has many difficulties in visualization due to limitations in hardware resources such as rendering speed, memory capacity, and graphic card.

The technical problem to be achieved by an embodiment of the present invention is to provide a method and device for storing a large amount of three-dimensional model information by simplifying it into multiple stages so as to facilitate visualization of the three-dimensional model.

In order to achieve the above technical task, an example of a method for storing a three-dimensional model according to an embodiment of the present invention includes the steps of: generating an Nth simplified model by reducing the number of shape data of a three-dimensional model representing at least one object in a certain space according to a predefined Nth (N is a natural number greater than or equal to 1) simplification ratio; storing the Nth simplified model in a database; and repeatedly performing the steps of generating the Nth simplified model and storing it in the database as many times as the number (N) of the predefined simplification ratios.

According to an embodiment of the present invention, by simplifying and storing three-dimensional model information in several steps, the processing of three-dimensional model information, such as visualization, search, and comparison, can be made quick and easy.

Figure 1 is a drawing showing a general outline of a three-dimensional model storage method according to an embodiment of the present invention;

Figure 2 is a drawing illustrating an example of a method for simplifying a three-dimensional model according to an embodiment of the present invention.

FIG. 3 is a flow chart illustrating an example of a method for generating a simplified model according to an embodiment of the present invention.

FIG. 4 is a drawing illustrating an example of a method for storing a simplified model according to an embodiment of the present invention.

FIG. 5 and FIG. 6 are diagrams illustrating an example of a method for storing a simplified model in object units according to an embodiment of the present invention, and

FIG. 7 is a diagram illustrating an example configuration of a 3D model storage device according to an embodiment of the present invention.

Hereinafter, a three-dimensional model storage method and device thereof according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

FIG. 1 is a drawing illustrating a general outline of a three-dimensional model storage method according to an embodiment of the present invention.

Referring to FIG. 1, when a 3D model storage device (100) receives a 3D model (110) that is a 3D model of a certain space, it creates at least one simplified model (130, 132, 134) for the 3D model and stores it in a database (120).

The 3D model (110) includes 3D data for at least one object, such as various structures or facilities above or below ground. For example, the 3D model (110) may be composed of 3D mesh data that represents the shape information of an object using polygonal shape data. Since representing a 3D model using polygonal mesh data is a technology that is already commonly used, a detailed description thereof will be omitted. A 3D model for a certain space, such as an underground culvert, may include 3D data for at least one object (e.g., various facilities, etc.).

The simplified model (130, 132, 134) is a model that reduces the amount of data in a large-capacity 3D model (110). The 3D model (110) is composed of a large amount of shape data to represent the surface of an object. For example, when representing the surface of an object with triangles, the smaller and more numerous the triangles are, the more similarly the surface of the object can be represented to reality. However, in this case, since the amount of 3D data representing the object increases, there is a disadvantage in that a lot of time and system resources are consumed for searches or visualizations. The simplified model (130, 132, 134) is a model that reduces the number of shape data in the 3D model (110) to increase the efficiency of searches or visualizations. The number of shape data can be reduced at various ratios, and a plurality of simplified models (130, 132, 134) can be generated according to the ratio of the reduction in the number of shape data. For example, the first simplified model (130) may be a model in which the number of shape data of the three-dimensional model (110) is reduced by 10%, and the second simplified model (132) may be a model in which the number of shape data of the three-dimensional model is reduced by 20%. An example of a method for generating simplified models (130, 132, 134) is illustrated in FIG. 2.

The 3D model storage device (100) stores the simplified models (130, 132, 134) in the database (120). At this time, the 3D model storage device (100) can store the information of each simplified model (130, 132, 134) as it is. However, if the 3D model (110) is 3D data of a space where multiple facilities (i.e., objects) exist, such as an underground tunnel, and multiple 3D models are created at any time according to changes occurring throughout the entire life cycle of multiple facilities, if each simplified model (130, 132, 134) is stored, there is an inconvenience in that multiple simplified models in the database must be searched and retrieved one by one when a query or visualization is required. As a method for solving this, the present embodiment proposes a method of distributing and storing each simplified model information (130, 132, 134) in multiple tables as an object unit. A specific method of storing the simplified model information as an object unit will be examined again in FIGS. 4 to 6.

FIG. 2 is a drawing illustrating an example of a method for simplifying a three-dimensional model according to an embodiment of the present invention.

Referring to FIG. 2, the 3D model storage device (100) selects a vertex (210) of the 3D model (200). This embodiment assumes that the 3D model is composed of triangle shape data. The 3D model storage device (100) can select an arbitrary vertex from the surface of the 3D model in the form of a triangle mesh or select vertices in the order of the number of connected edges. In addition to this, various methods for selecting vertices can be applied to this embodiment.

The 3D model storage device (100) deletes shape data (i.e., triangles) adjacent to the selected vertex to create a hole (220, 230), and remodels the hole with at least one shape data (i.e., triangles) so that there are no vertices in the hole (240). In the present embodiment, the number of triangles connected to the selected vertex (210) is six, while the number of triangles created by remodeling the hole is three. In other words, the number of shape data representing the object is reduced by three through the simplification process.

The 3D model storage device (100) repeatedly performs the process of selecting vertices, creating holes, and remodeling until the number of shape data of the object is reduced to a predefined number. For example, if the number of shape data of a 3D model is 100 and a simplified model is to be created by reducing it by 10%, the 3D model storage device (100) repeatedly performs the remodeling process (200 to 240) until the number of shape data becomes 90.

FIG. 3 is a flowchart illustrating an example of a method for generating a simplified model according to an embodiment of the present invention.

Referring to FIG. 3, the 3D model storage device (100) receives 3D model information (S300). The 3D model storage device (100) generates a simplified model by simplifying the 3D model according to a predefined simplification ratio (S310). At least one simplification ratio can be defined. For example, the 3D model storage device (100) may predefine multiple simplification ratios, such as a first simplification ratio of 10%, a second simplification ratio of 20%, etc. Alternatively, the 3D model storage device may receive multiple simplification ratios from a user.

The 3D model storage device (100) determines whether all simplified models according to multiple simplification ratios have been created when multiple simplification ratios are defined (S320). For example, if the simplification ratios are defined from the first simplification stage to the Nth simplification stage, the 3D model storage device (100) creates the first simplified model according to the first simplification ratio, determines the second simplification ratio in the next stage (S300), and then creates the second simplified model according to the second simplification ratio (S310). In this way, the 3D model storage device (100) creates the first simplified model to the Nth simplified model. The 3D model storage device (100) can create the simplified models of each stage based on the same original 3D model each time. For example, the 3D model storage device (100) can use the same 3D model to create both the first simplified model and the Nth simplified model. Of course, as another example, when creating a simplified model starting from a low simplification ratio to a high simplification ratio, the simplified model created in the previous step can be used to create the simplified model of the current step.

The 3D model storage device (100) stores the first simplified model to the Nth simplified model in a database (S340). An example of a method for storing in a database is discussed again in FIG. 4 and below.

FIG. 4 is a diagram illustrating an example of a method for storing a simplified model according to an embodiment of the present invention.

Referring to FIG. 4, the 3D model storage device (100) stores a plurality of simplified models created with different simplification ratios. For example, the plurality of simplified models can be stored as array data (400). The array data (400) includes an array (SceneCalss[]) (410) for storing each simplified model. This embodiment assumes that a four-stage simplified model is created, and illustrates four arrays (410) for storing four simplified models.

In the array (SceneClass) (410) that stores each simplified model, there is an array (MeshDataClass) (430) for storing object units. If there is only one object in the simplified model, the array data (430) can be composed of one.

The array (MeshDataClass) (430) storing object information may include various fields such as a name field (440), a mesh field (442), and a material field (444) for storing three-dimensional data of the object. The mesh field (442) includes position information of vertices of shape data representing the surface of the object, and the material field (444) includes surface property information such as texture or color of the shape data. In addition to these, various fields for storing three-dimensional data of the object may exist.

The 3D model storage device (100) can store and manage the simplified model in the database as a data structure as in this embodiment. However, if the data capacity of the simplified model is large and multiple simplified models are continuously created to reflect multiple situations occurring in the life cycle of multiple objects (i.e., multiple facilities in an underground culvert, etc.) in the space represented by the simplified model, it may be inconvenient to store and manage the information of the objects in an integrated manner. Accordingly, the 3D model storage device (100) proposes a method of storing the simplified model for each object, which will be examined again in FIGS. 5 and 6.

FIGS. 5 and 6 are diagrams illustrating an example of a method for storing a simplified model in object units according to an embodiment of the present invention.

Referring to FIGS. 5 and 6 together, the 3D model storage device (100) includes a geometry table (510), a vertex table (520), a material table (530), and a mesh table (540) for storing at least one simplified model (500). The 3D model storage device (100) distributes and stores 3D mesh data of objects stored in each simplified model (502, 504) in each table (510, 520, 530, 540). In the following, for convenience of explanation, it is assumed that when creating a simplified model, information of the simplified model is created in a data structure such as FIG. 4.

Referring to FIG. 6, in the geometry table (510), the entire vertex information of the object (Geom (location information (x, y, z) of each vertex, etc.), Bufsize (data storage size), color (color information, etc.)) is stored by mapping it with the geometry identification information (gemoID) assigned to the object. For example, suppose that four simplified models are generated from a three-dimensional model including four objects. In this case, the 3D model storage device (100) stores the entire vertex information of the mesh data constituting the first object of the first simplified model (502) in the geometry table (510) by mapping it with the geometry identification information (geomID) assigned to the first object. In addition, the 3D model storage device (100) stores the entire vertex information of the mesh data constituting the second object of the first simplified model (502) in the geometry table (510) by mapping it with the geometry identification information (geomID) assigned to the second object. In this way, the 3D model storage device (100) stores the vertex information of each object of the first to third simplified models in the geometry table (510) by distinguishing the vertex information of each object with the geometric identification information (geomID) uniquely assigned to each object. That is, in the geometry table (510), the vertex information of multiple objects of multiple simplified models is integrated and stored using the geometric identification information (geomID).

In the vertex table (520), individual vertex information including the order (map_index) and position value (map_postion) of each vertex of the object stored in the geometry table (510) is stored by mapping it with the vertex identification information (vtxID) assigned to each vertex. In order to distinguish which object the vertex information is for, the vertex table (520) also stores the geometry identification information (geomID) of the geometry table (510). In another embodiment, when storing information on an object of the simplified model of the Mth (M is a natural number greater than or equal to 2), the vertex table (520) may include the vertex identification information (upper_xtxID) of the vertex table for the same object of the first simplified model information.

In the material table (530), the surface property information (i.e., surface texture or color, etc.) (material, map_texture) of each object of each simplified model is stored by mapping it with the material identification information (materialID) assigned to each object.

The 3D model storage device (100) stores object information such as simplification step information of a simplified model, along with geometric identification information (geomID) and material identification information (materialID) of each object stored in the geometry table (510) and material table (530) of the database, in a mesh table (540) by mapping them to object identification information (meshUID) assigned to each object. In another embodiment, when storing information of an object of the M (M is a natural number greater than or equal to 2) simplified model, the mesh table (540) may include object identification information (scrid) of the mesh table for the same object of the first simplified model.

If the 3D model storage device (100) wants to search for information on a specific object of a specific simplified model, it searches the mesh table (540) based on the object identification information (meshUID) of the object to determine material identification information (materialID) and geometric identification information (geomID) for the object. Then, the 3D model storage device (100) searches the material table (530) and the geometric table (510) based on the material identification information (materialID) and the geometric identification information (geomID) to search for geometric information such as vertices of the object and surface attribute information, and can visualize the object based on the searched information.

Even when 3D models are created at multiple points in time and multiple simplified models are created accordingly, the 3D model storage device (100) allows the user to easily search for and visualize information on a specific object of a specific simplified model at a desired point in time using only the object identification information (meshUID) of the object.

Referring to FIG. 7, the 3D model storage device (100) includes a simplification unit (700) and a storage unit (710). In one embodiment, the 3D model storage device (100) may be implemented as a computing device including a memory, a processor, and an input/output device. In this case, each configuration may be implemented as software, loaded into the memory, and then driven by the processor.

The simplification unit (700) generates a simplified model that simplifies the surface information of a three-dimensional model that models a certain space in which at least one object exists. The simplification unit (700) can generate a plurality of different simplified models according to the simplification ratio as shown in Fig. 1. The simplification unit (700) can generate a simplified model by reducing the number of shape data, and an example of this is illustrated in Fig. 2.

The storage unit (710) can store the simplified model in multiple tables in units of objects. For example, the storage unit (710) can store and manage the 3D data of each object of each simplified model using four tables: a geometry table, a vertex table, a material table, and a mesh table. Examples of this are illustrated in FIGS. 5 and 6.

Each embodiment of the present invention can also be implemented as computer-readable code on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices that store data that can be read by a computer system. Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, SSD, optical data storage devices, etc. In addition, the computer-readable recording medium can be distributed over network-connected computer systems so that the computer-readable code can be stored and executed in a distributed manner.

The present invention has been described with reference to preferred embodiments thereof. Those skilled in the art will appreciate that the present invention may be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a restrictive perspective. The scope of the present invention is indicated by the claims, not the foregoing description, and all differences within the scope equivalent thereto should be interpreted as being included in the present invention.

Claims

A step of generating an Nth simplified model by reducing the number of shape data of a three-dimensional model representing at least one object in a given space according to a predefined Nth (N is a natural number greater than or equal to 1) simplification ratio;

A step of storing the above Nth simplified model in a database; and

A method for storing 3D model information, characterized by including a step of repeatedly performing the step of generating the Nth simplified model as many times as the number (N) of predefined simplification ratios and the step of storing the same in the database.
In the first paragraph, the step of generating the Nth simplified model is:

A step of selecting a vertex of the above 3D model and deleting shape data adjacent to the selected vertex to create a hole;

A step of remodeling the hole with at least one shape data so that there is no vertex in the hole; and

A method for storing 3D model information, characterized by including a step of repeatedly performing the process of creating and remodeling the hole until the number of shape data of the 3D model is reduced to a number corresponding to the Nth simplification ratio.
In the first paragraph, the step of storing in the database is,

For each object included in the above Nth simplified model, a step of mapping the entire vertex information of the object to the geometric identification information assigned to each object and storing it in a geometry table;

A step of storing individual vertex information including the order and position value of each vertex stored in the above geometry table in a vertex table by mapping it with vertex identification information assigned to each vertex;

A step of storing attribute information including texture information of an object surface in a material table by mapping it with material identification information assigned to each object; and

A method for storing 3D model information, characterized by including a step of storing object information including the geometric identification information, the material identification information, and the simplification stage information of the Nth simplified model for each object in a mesh table by mapping the object identification information assigned to each object.
In the third paragraph,

A method for storing three-dimensional model information, characterized in that the mesh table for an object of a simplified model of Singgi M (M is a natural number greater than or equal to 2) includes object identification information of the mesh table for the same object of the first simplified model.
In the third paragraph,

A method for storing three-dimensional model information, characterized in that the vertex table for an object of a simplified model of Singgi M (M is a natural number greater than or equal to 2) includes vertex identification information of a vertex table for the same object of the first simplified model information.