WO2010013854A1

WO2010013854A1 - Three dimensional geographical information client apparatus, server apparatus and three dimensional geographical information system having the same

Info

Publication number: WO2010013854A1
Application number: PCT/KR2008/004469
Authority: WO
Inventors: Gyung Min Kim
Original assignee: Woodai Cals Co, . Ltd
Priority date: 2008-07-30
Filing date: 2008-07-31
Publication date: 2010-02-04
Also published as: KR20100013059A; KR100956416B1

Abstract

The present invention relates to a three-dimensional geographical information client apparatus and server apparatus, and a three-dimensional geographical information system including the same. The three-dimensional geographical information client apparatus comprises: a three- dimensional geographical information generating section for receiving the data stored in the three-dimensional geographical information server apparatus and generating three-dimensional geographical information. The three-dimensional geographical information generating section comprises: a three-dimensional geographical information visualization module for managing data necessary for generating the three-dimensional geographical information; and a data transmitting and receiving module for requesting data from the three-dimensional geographical information server apparatus or receiving data from the three-dimensional geographical information server apparatus. The three-dimensional geographical information visualization module comprises a screen clipping unit for selecting a visible interval seen at an arbitrary view point, the screen clipping unit simultaneously selecting a topographic polygon, a shape object and a model object within the selected visible interval.

Description

THREE DIMENSIONAL GEOGRAPHICAL INFORMATION CLIENT APPARATUS, SERVER APPARATUS AND THREE DIMENSIONAL GEOGRAPHICAL INFORMATION SYSTEM

HAVING THE SAME Technical Field

[1] The present invention relates to a three-dimensional geographical information client apparatus and server apparatus, and a three-dimensional geographical information system including the same, and more particularly, to a three-dimensional geographical information client apparatus and server apparatus, and a three-dimensional geographical information system including the same, in which the streaming speed of three-dimensional geographical information data is improved. Background Art

[2] A geographical information system (GIS) is an information system which processes data through the interconnection of graphic data appearing at a spatial position and attribute data associated with the graphic data for the purpose of supporting the decision-making ability of a human being in a broad sense. This information system also is an integrated system of hardware, software, geographical data and human resource used to efficiently collect, store, update, process, analyze and output a variety of types of geographical information.

[3] As such a geographical information system (GIS) is currently extended to service areas including web services, mobile services, and so forth from a conventional package software market, mobile GISs, Internet GISs, etc., come into spotlight. In addition, as the image processing technology is step by step transformed from two- dimension to three-dimension in a video field, the ripple effect of the geographical information system (GIS) on its related fields or sectors is sharply increased. That is, application of the geographical information system (GIS) is gradually diversified in various fields including a public sector, a military sector and a general industrial sector, and hence a three-dimensional geographical information system (GIS) for providing three-dimensional (3D) volumetric spatial information and performing spatial analysis is highly spotlighted.

[4] The recent rapid development of the information technology allows a platform implementing a three-dimensional (3D) virtual city to be transferred from a workstation- based PC to an Internet-based PC. Owing to this, an active attempt is being made to utilize a three-dimensional city simulation. Particularly, the three-dimensional city simulation is used or its research is in progress in various applicable fields such as visualization, simulation, three-dimensional analysis and the like

[5] However, it is true that due to restraints of a processing speed, a three-dimensional processing technique, a virtual reality technology and the like of large-capacity spatial data, the three-dimensional city simulation has been limited in use to a short-term project such as a spatial analysis system for some experts, simulation for architectural and civil construction, or the like, rather than aimed at being used sustainably through construction and maintenance & management of information. The recent remarkable advancement of a computer hardware partly resolves such limitations, but the three- dimensional city simulation is merely applied to relatively simple three-dimensional space representation and management, etc., as in an underground facility management system and the like of public institutions and local governments. Even in case of a system implementing a city in a three-dimensional scheme, there is a limitation in reproducing a contiguous urban landscape by lowering fineness of representation in order to represent a broad region. In fact, the use of the three-dimensional city simulation is limited to a narrow space for implementation to reproduce the contiguous urban landscape.

[6] Therefore, there is an urgent need for a three-dimensional geographical information system enabling more rapid and precise three-dimensional city simulation on a web. Disclosure of Invention

Technical Problem

[7] Accordingly, the present invention has been made to solve the above-mentioned problems associated with the prior art, and it is an object of the present invention to provide an Internet-based three-dimensional geographical information system which enables improvement of the processing speed of three-dimensional geographical information, utilization of a high-resolution image and realistic building modeling process. Technical Solution

[8] To accomplish the above object, according to one exemplary embodiment of the present invention, there is provided a three-dimensional geographical information client apparatus connected to a tree-dimensional geographical information server apparatus through a network. The three-dimensional geographical information client apparatus includes a three-dimensional geographical information generating section for receiving the data stored in the three-dimensional geographical information server apparatus and generating three-dimensional geographical information. The three- dimensional geographical information generating section includes: a three-dimensional geographical information visualization module for managing data necessary for generating the three-dimensional geographical information; and a data transmitting and receiving module for requesting data from the three-dimensional geographical information server apparatus or receiving data from the three-dimensional geographical information server apparatus. The three-dimensional geographical information visualization module includes a screen clipping unit for selecting a visible interval seen at an arbitrary view point, the screen clipping unit simultaneously selecting a topographic polygon, a shape object and a model object within the selected visible interval, and the data transmitting and receiving module requests data associated with the topographic polygon, the shape object and the model object selected by the screen clipping unit from the three-dimensional geographical information server apparatus and receives the data from the three-dimensional geographical information server apparatus.

[9] The three-dimensional geographical information visualization module further includes a model object data management unit for managing a request for a model object data stored in the three-dimensional geographical information server apparatus, each model object data within the selected visible interval comprises texture information divided into at least two levels of detail (LoD), and the model object data management unit transfers a request for the model object data having different levels of detail depending on a visible distance or a degree of importance of the model object to the data transmitting and receiving module.

[10] The three-dimensional geographical information visualization module further includes a topographic polygon data management unit for managing a request for a topographic polygon data stored in the three-dimensional geographical information server apparatus, and the topographic polygon data management unit transfers a request for the topographic polygon data whose kinds of a vertex buffer and a bitmap index are the same among the topographic polygon data stored in the three-dimensional geographical information server apparatus to the data transmitting and receiving module.

[11] The three-dimensional geographical information visualization module further includes a shape object data management unit for managing a request for a shape object data stored in the three-dimensional geographical information server apparatus, and the shape object data management unit adds color information to a shape object data transmitted thereto from the three-dimensional geographical information server apparatus, the color information being in the form of a coordinate value of a shared texture for color designation stored in the memory.

[12] The data transmitting and receiving module simultaneously makes a plurality of data requests from the three-dimensional geographical information server apparatus.

[13] The three-dimensional geographical information client apparatus further includes: a memory for storing data, the memory including the three-dimensional geographical in- formation generating section; a central processor unit for controlling the operation of the three-dimensional geographical information generating section; and a display section for displaying the generated three-dimensional geographical information thereon.

[14] The central processor unit processes data in a multi-thread manner, and the multi- thread includes a network access thread of downloading data requested from three- dimensional geographical information server apparatus, a update thread of updating the downloaded data in the memory, and a main thread of performing a task other than tasks performed in the network access thread and the update thread.

[15] The multi- thread establishes a critical section in order to minimize mutual data interference between the respective threads.

[16] According to another exemplary embodiment of the present invention, there is provided a three-dimensional geographical information server apparatus connected to a plurality of three-dimensional geographical information client apparatuses through a network. The three-dimensional geographical information server apparatus includes: a geographical information database including a topographic polygon data file for storing a topographic polygon data therein, a shape object data file for storing a shape object data therein, and a model object data file for storing a model object data therein; and a web server including a server data retrieving section for retrieve data requested from each of the three-dimensional geographical information client apparatuses from the geographical information database, and a server data transmitting and receiving section for receiving a data request from each of the three-dimensional geographical information client apparatuses, or transmitting the data retrieved by the server data retrieving section to each of the three-dimensional geographical information client apparatuses. The model object data includes texture information divided into at least two levels of detail (LoD) by each model object.

[17] The web server maintains a plurality of transfer queues corresponding to a plurality of data requests simultaneously transmitted thereto from the plurality of three- dimensional geographical information client apparatuses.

[18] The topographic polygon data includes an elevation data and an image data, the image data including a variety of kinds of image data for the same region.

[19] According to another exemplary embodiment of the present invention, there is provided a three-dimensional geographical information system including a three- dimensional geographical information server apparatus and a plurality of three- dimensional geographical information client apparatuses which are connected to each other through a network. The three-dimensional geographical information server apparatus comprises: a geographical information database including a topographic polygon data file for storing a topographic polygon data therein, a shape object data file for storing a shape object data therein, and a model object data file for storing a model object data therein; and a web server including a server data retrieving section for retrieve data requested from each of the three-dimensional geographical information client apparatuses from the geographical information database, and a server data transmitting and receiving section for receiving a data request from each of the three-dimensional geographical information client apparatuses, or transmitting the data retrieved by the server data retrieving section to each of the three-dimensional geographical information client apparatuses. The model object data includes texture information divided into at least two levels of detail (LoD) by each model object, and each of the three-dimensional geographical information client apparatuses includes a three-dimensional geographical information generating section for receiving the data stored in the three-dimensional geographical information server apparatus and generating three-dimensional geographical information, a memory for storing data, the memory including the three-dimensional geographical information generating section, and a central processor unit for controlling the operation of the three-dimensional geographical information generating section. The central processor unit processes data in a multi-thread manner, the multi-thread includes a network access thread of downloading data requested from three-dimensional geographical information server apparatus, a update thread of updating the downloaded data in the memory, and a main thread of performing a task other than tasks performed in the network access thread and the update thread. [20]

Advantageous Effects

[21] According to the three-dimensional geographical information system of the present invention, the processing speed of three-dimensional geographical information can be improved, a high-resolution image can be utilized, and realistic building modeling process is enabled. Brief Description of Drawings

[22] Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

[23] FIG. 1 is a schematic block diagram illustrating the construction of a three-dimensional geographical information system according to a preferred embodiment of the present invention;

[24] FIG. 2 is a functional block diagram illustrating a three-dimensional geographical information system according to a preferred embodiment of the present invention;

[25] FIG. 3 is a schematic block diagram illustrating the construction of a three-di- mensional geographical information generating section of a three-dimensional geographical information client apparatus according to a preferred embodiment of the present invention;

[26] FIG. 4 is a schematic block diagram illustrating the construction of a three-dimensional geographical information visualization module of the three-dimensional geographical information generating section;

[27] FIG. 5 is a schematic block diagram illustrating the construction of a topographic polygon data file of a geographical information database;

[28] FIG. 6 is a schematic block diagram illustrating the configuration of an image data of the topographic polygon data file;

[29] FIG. 7 is a schematic block diagram illustrating the construction of a model object data file of the geographical information database;

[30] FIGs. 8 and 9 are diagrams illustrating one example of the structure of the model object data;

[31] FIGs. 10 and 11 are a flowchart illustrating a screen clipping process for selecting a visible interval seen at an arbitrary view point, and a diagram illustrating a process for generating a quadtree;

[32] FIG. 12 is a flowchart illustrating a process of generating and displaying a topographic polygon;

[33] FIG. 13 is a flowchart illustrating one example of a process of generating and displaying a shape object;

[34] FIG. 14 is a flowchart illustrating a process of generating and displaying a model object;

[35] FIG. 15 is a flowchart illustrating the communication process performed between a three-dimensional geographical information client apparatus and a three-dimensional geographical information server apparatus; and

[36] FIG. 16 is a flowchart illustrating a process of minimizing mutual data interference upon the application of a multi-thread in a central processor unit (CPU) of a three- dimensional geographical information client apparatus. Best Mode for Carrying out the Invention

[37] Now, a preferred embodiment of the present invention will be described hereinafter with reference to the accompanying drawings.

[38] FIG. 1 is a schematic block diagram illustrating a three-dimensional geographical information system according to a preferred embodiment of the present invention, and FIG. 2 is a functional block diagram illustrating a three-dimensional geographical information system according to a preferred embodiment of the present invention.

[39] Referring to FIGs. 1 and 2, the three-dimensional geographical information system includes a three-dimensional geographical information server apparatus 300, a plurality of three-dimensional geographical information client apparatuses 500, and a communication network 400 disposed between the three-dimensional geographical information server apparatus 300 and the plurality of three-dimensional geographical information client apparatuses 500 for interconnecting the three-dimensional geographical information server apparatus 300 and the plurality of three-dimensional geographical information client apparatuses 500. The three-dimensional geographical information server apparatus 300 includes a web server 100 and a geographical information database 200.

[40] The web server 100 of the three-dimensional geographical information server apparatus 300 includes a communication interface 110, a server data transmitting and receiving section 130 and a server data retrieving section 150. The geographical information database 200 includes a topographic polygon data file 210, a shape object data file 230 and a model object data file 250.

[41] The three-dimensional geographical information server apparatus 300 basically functions as a file server. That is, the three-dimensional geographical information server apparatus 300 retrieves the data requested by the plurality of three-dimensional geographical information client apparatuses 500 from the geographical information database 200 and transmits the retrieved data to the three-dimensional geographical information client apparatuses 500.

[42] The communication interface 110 of the web server 100 is connected to the communication network 400 so as to perform the data communication between the web server 100 and the communication network 400. The server data transmitting and receiving section 130 serves to receive data request information from the three-dimensional geographical information client apparatuses 500, or transmit the data retrieved from the geographical information database 200 to the three-dimensional geographical information client apparatuses 500. The server data retrieving section 150 serves to retrieve data corresponding to the data request information transmitted from the three- dimensional geographical information client apparatuses 500 from the geographical information database 200 in response to the data request information.

[43] The geographical information database 200 includes a topographic polygon data file

210, a shape object data file 230 and a model object data file 250, and may store two- dimensional geographical information data, etc., which is not shown in the drawings, in addition to the three-dimensional geographical information data.

[44] The topographic polygon data file 210 stores a topographic polygon data, which means a data having an elevation value for an arbitrary point.

[45] A technique for generating a three-dimensional topography can employ a three- dimensional surface modeling method in which an elevation value as an attribute is allocated to continuous two-dimensional x- and y-coordinates so as to process data. Since such a surface modeling method employs a continuous surface as a modeling target but actually makes it difficult to store the elevation values of all the points, it utilizes a sampling method in which the topographic polygon data is represented as the elevation value of only a representative point. An example of an elevation data obtained by using such a sampling method includes a digital elevation model (DEM) data, a triangulated irregular network (TIN) data or the like. In this embodiment, the topographic polygon data uses the DEM data, but not limited thereto.

[46] The shape object data file 230 stores a shape object data which is used in a three- dimensionalization process using a shape, i.e., a two-dimensional data. The shape object data contains a shape and an elevation value. Such a three-dimensionalization process is a method in which in case of a building or facility that is difficult to represent using a basic figure, its cross-section is used as a shape and then an elevation value is allocated to the shape so as to three-dimensionalize the building or facility.

[47] The model object data file 250 stores a model object data which contains three- dimensional geometry information and texture information. The texture information includes information regarding the outer appearance of a building or the surface of a geographical feature, etc., that is processed using aerial photographs, computer graphics or the like.

[48] Each three-dimensional geographical information client apparatus 500 includes a communication interface 510, a central processor unit (CPU) 530, a memory 550, a three-dimensional geographical information generating section 560 and a display section 570.

[49] The communication interface 510 is connected to the communication network 400 so as to perform the data communication between the three-dimensional geographical information client apparatuses and the communication network 400. The central processor unit 530 serves to control the operations of the three-dimensional geographical information generating section 560 of each of three-dimensional geographical information client apparatus. The memory 550 includes the three-dimensional geographical information generating section 560 and serves to store a variety of data including data transmitted from the three-dimensional geographical information server apparatus 300. The three-dimensional geographical information generating section 560 serves to receive the requested data from the three-dimensional geographical information server apparatus and generate three-dimensional geographical information. The display section 570 serves to display the three-dimensional geographical information generated from the three-dimensional geographical information generating section 560 thereon.

[50] In the meantime, the central processor unit 530 processes data in a multi-thread manner in order to simultaneously execute a plurality of tasks, and establishes a critical section in order to minimize mutual data interference between the respective threads. In this case, a multi-thread includes a update thread of decompressing a compressed data downloaded from the three-dimensional geographical information server apparatus 300 and updating the decompressed data in the memory 550, a network access thread of downloading data requested from the three-dimensional geographical information server apparatus 300, and a main thread of performing a task, for example, a rendering other than tasks performed in the network access thread and the update thread. Like this, the central processor unit 530 of the three-dimensional geographical information client apparatuses 500 performs a task while dividing it into the following three threads by each function: the update thread, the network access thread and the main thread. The central processor unit 530 performs a task in a parallel-processing manner by applying the multi-thread. As a result, the efficiency of the central processor unit 530 of the three-dimensional geographical information client apparatuses 500 can be maximized. A method for minimizing the mutual data interference upon application of the multi-thread by the central processor unit 530 will be discussed in more detail hereinafter with reference to FIG. 16.

[51] The construction and function of the three-dimensional geographical information generating section 560 will be described hereinafter with reference to the drawings.

[52] FIG. 3 is a schematic block diagram illustrating the construction of a three-dimensional geographical information generating section of a three-dimensional geographical information client apparatus according to a preferred embodiment of the present invention, and FIG. 4 is a schematic block diagram illustrating the construction of a three-dimensional geographical information visualization module of the three- dimensional geographical information generating section.

[53] Referring to FIG. 3, the three-dimensional geographical information generating section 560 includes a data retrieving module 561, a data transmitting and receiving module 562, a data editing module 563 and a three-dimensional geographical information visualization module 565. The data retrieving module 561 functions to retrieve a desired data among data transmitted thereto from the three-dimensional geographical information server apparatus. The data transmitting and receiving module 562 functions to request data from the three-dimensional geographical information server apparatus 300 or receives data from the three-dimensional geographical information server apparatus 300. Also, the data editing module 563 functions to edit data transmitted thereto from the three-dimensional geographical information server apparatus 300, and the three-dimensional geographical information visualization module 565 functions to manage data necessary for generating the three-dimensional geographical information. [54] Referring to FIG. 4, the three-dimensional geographical information visualization module 565 includes a screen clipping unit 566, a topographic polygon data management unit 567, a shape object data management unit 568 and a model object data management unit 569.

[55] The screen clipping unit 566 serves to select a tile included in a visible interval seen at an arbitrary view point. In this case, the tile means a minimum region unit constituting an entire map. The screen clipping unit 566 simultaneously selects a topographic polygon, a shape object and a model object within the selected visible interval. The data associated with the topographic polygon, the shape object and the model object selected by the screen clipping unit 566 is requested from the three- dimensional geographical information server apparatus by the data transmitting and receiving module 562.

[56] The topographic polygon data management unit 567 serves to manage a request for a topographic polygon data stored in the geographical information database 200. The topographic polygon data management unit 567 transfers a request for the topographic polygon data whose kinds of a vertex buffer and a bitmap index are the same among the topographic polygon data stored in the geographical information database 200 to the data transmitting and receiving module 562. The web server 100 retrieves the topographic polygon data whose kinds of a vertex buffer and a bitmap index are the same from the geographical information database 200 in response to information regarding the request for the data transmitted to the web server 100 from the data transmitting and receiving module 562, and then transmits the retrieved topographic polygon data to the data transmitting and receiving module 562. When the retrieved topographic polygon data transmitted to the data transmitting and receiving module 562 is transferred to the display section 570, the same topography as the retrieved topographic polygon data is displayed at a time on the display section 570, so that a rendering speed is greatly improved.

[57] The shape object data management unit 568 serves to manage a request for a shape object data stored in geographical information database 200. The shape object data management unit 568 transfers the request for the shape object data stored in geographical information database 200 to the data transmitting and receiving module 562. The web server 100 retrieves the shape object data from the geographical information database 200 in response to information regarding the request for the shape object data transmitted to the web server 100 from the data transmitting and receiving module 562, and then transmits the retrieved shape object data to the data transmitting and receiving module 562.

[58] Meanwhile, the shape object data management unit 568 can serve to simultaneously display colors for respective shape objects. Stored previously in the memory 560 is a shared texture for color designation which is stored with a color by each coordinate value. The shape object data management unit 568 adds color information to the shape object data transmitted thereto from the web server 100. At this time, the color information for each shape object data is added in the form of the coordinate value of the shared texture for color designation. Then, in case where the colors of arbitrary shape objects are displayed, the colors of shared textures for color designation corresponding to coordinate values which arbitrary shape objects hold are retrieved and the retrieved colors are displayed together on the arbitrary shape objects.

[59] The model object data management unit 567 serves to manage a request for a model object data stored in the geographical information database 200. Each model object data within the selected visible interval includes texture information having at least two levels of detail (LoD). The model object data management unit 567 transfers a request for the model object data having different levels of detail depending on a visible distance or a degree of importance of the model object data to the data transmitting and receiving module. The web serer 100 retrieves, a model object data having a level of detail corresponding to information regarding the request of the model object data in response to information regarding the request of the model object data transmitted thereto from the data transmitting and receiving module 562, from the geographical information database 200, and then transmits the retrieved model object data to the data transmitting and receiving module 562. When the model object data received by the data transmitting and receiving module 562 is transferred to the display section 570, the display section 570 displays three-dimensional geographical information having different levels of detail within the visible interval thereon.

[60] If texture information having the highest level of detail for all the model objects within the visible interval is displayed, a memory load occurs, which results in a remarkable reduction in the processing speed. Thus, when the request for data is made by determining a necessary level of detail by each model object as in the present invention, the data downloading speed is enhanced and the memory load can be reduced.

[61] FIG. 5 is a schematic block diagram illustrating the construction of a topographic polygon data file of a geographical information database, and FIG. 6 is a schematic block diagram illustrating the configuration of an image data of the topographic polygon data file.

[62] Referring to FIGs. 5 and 6, a topographic polygon data of the topographic polygon data file 210 includes an elevation data 211 such as DEM data and an image data 215. In this case, the image data 215 manages a variety of kinds of image data for the same region in a layer-based manner. That is, the image data 215 stores image data associated with satellite or aerial photographs in a first layer and manages them. The image data 215 stores images having coordinate values in a second layer and manages them.

[63] FIG. 7 is a schematic block diagram illustrating the construction of a model object data file of the geographical information database.

[64] Referring to FIG. 7, the model object data includes texture information divided into at least two levels of detail (LoD) by each model object. In this embodiment, although the texture information is divided into three LoDs, i.e., LoD 1 to LoD 3 for an arbitrary model object, it is merely illustrative for the sake of convenience of explanation, but not limited thereto.

[65] FIGs. 8 and 9 are diagrams illustrating one example of the structure of the model object data.

[66] Referring to FIGs. 8 and 9, in case of the model object data, information regarding whether or not any building or facility exists in each tile is stored in the form of an index list as shown in FIG. 9.

[67] FIGs. 10 and 11 are a flowchart illustrating a screen clipping process for selecting a visible interval seen at an arbitrary view point, and a diagram illustrating a process for generating a quadtree.

[68] Referring to FIG. 10, first, a step is performed in which an arbitrary view point is determined or shifted (S7801). Then, a step is performed in which a clipping grid is generated (S802). At this time, the clipping grid is generated in such a fashion that respective tiles are added once more by 2*2 (see FIG. 11). Thereafter, the central processing unit (CPU) performs a step of determining whether or not remaining tiles exist (S803).

[69] If it is determined at S 803 that the remaining tiles exist, the program returns to the step S 802. On the other hand, if it is determined at S 803 that the remaining tiles do not exist, the program proceeds to a step S804 where a quadtree is generated.

[70] Subsequently, a step is performed in which a seek of the quadtree is performed from an upper position to a lower position, and a visible interval seen on the display section at an arbitrary view point is selected (S805). Then, a topographic polygon, a shape object and a model object existing within the selected visible interval are simultaneously selected (S806).

[71] In this manner, the topographic polygon, the shape object and the model object are simultaneously selected through the screen clipping, so that the display or simulation speed of the three-dimensional geographical information can be increased.

[72] FIG. 12 is a flowchart illustrating a process of generating and displaying a topographic polygon.

[73] Referring to FIG. 12, first, topographic polygon data is stored in the geographical information database of the three-dimensional geographical information server apparatus (SlOOl). The three-dimensional geographical information client apparatus performs a step of classifying the topographic polygon in the order of a vertex buffer and a bitmap index (S 1002). In this case, the vertex buffer refers to information regarding a point, and the bitmap index refers to information regarding a line interconnecting a point and a point.

[74] Thereafter, the three-dimensional geographical information client apparatus transmits information regarding a request for the topographic polygon data whose kinds of the vertex buffer and the bitmap index are the same to the three-dimensional geographical information server apparatus (S 1003).

[75] The three-dimensional geographical information server apparatus retrieves the topographic polygon data corresponding to the data request information transmitted thereto from the three-dimensional geographical information client apparatus (S 1004).

[76] Then, the three-dimensional geographical information server apparatus transmits the retrieved topographic polygon data, i.e., the topographic polygon data whose kinds of the vertex buffer and the bitmap index are the same to the three-dimensional geographical information client apparatus (S 1005).

[77] Thereafter, the dimensional geographical information client apparatus performs a step of displaying the topographic polygon data transmitted thereto from the three- dimensional geographical information server apparatus together (S 1006). In this manner, the topographic polygon data whose kinds of the vertex buffer and the bitmap index are the same are displayed together so that the rendering speed can be maximized.

[78] FIG. 13 is a flowchart illustrating one example of a process of generating and displaying a shape object.

[79] Referring to FIG. 13, first, the three-dimensional geographical information server apparatus performs a step of dividing a shape object data into intervals suitable for batching (SI lOl). Thereafter, the three-dimensional geographical information client apparatus performs a step of generating one shared texture for color designation for changing a color of each shape object (Sl 102).

[80] Subsequently, the three-dimensional geographical information client apparatus performs a step of designating a color position using UV coordinates and storing it (Sl 103).

[81] When the three-dimensional geographical information client apparatus requests each shape object data from the three-dimensional geographical information server apparatus, the three-dimensional geographical information server apparatus transmits the requested shape object data to the three-dimensional geographical information client apparatus (S 1104).

[82] The color information is added to each shape object data in the form of the co- ordinate value of the shared texture for color designation. Then, the colors of shared textures for color designation corresponding to coordinate values which arbitrary shape objects hold are retrieved and the retrieved colors are displayed together on the arbitrary shape objects (S 1105).

[83] FIG. 14 is a flowchart illustrating a process of generating and displaying a model object.

[84] Referring to FIG. 14, first, the three-dimensional geographical information server apparatus divides texture information for each model object data into at least two levels of detail (LoD), and stores it (S 1201).

[85] The three-dimensional geographical information client apparatus determines the level of a level of detail (LoD) depending on a visible distance or a degree of importance of each model object within the visible interval (S 1202). For example, in case of a building whose visible distance is short, a higher LoD is determined. On the contrary, in case of a building whose visible distance is long, a lower LoD is determined.

[86] The three-dimensional geographical information client apparatus performs a step of requesting texture information corresponding to a LoD of each model object from the three-dimensional geographical information server apparatus (S 1203).

[87] The three-dimensional geographical information server apparatus performs a step of retrieving the data requested by the three-dimensional geographical information client apparatus (S 1204), and then transmitting the retrieved data to the three-dimensional geographical information client apparatus (S 1205).

[88] The three-dimensional geographical information client apparatus performs a step of displaying the model object data transmitted thereto from the three-dimensional geographical information server apparatus (S 1206).

[89] As described above, the three-dimensional geographical information client apparatus determines a necessary LoD by each model object, and then requests data corresponding to the LoD from the three-dimensional geographical information server apparatus, so that the downloading speed of data is enhanced and the memory load can be reduced.

[90] FIG. 15 is a flowchart illustrating the communication process performed between a three-dimensional geographical information client apparatus and a three-dimensional geographical information server apparatus.

[91] Generally, the communication between the server apparatus and the client apparatus involves a time delay to some extent. Thus, in case where the request for data by the client apparatus and the response to the data request by the server apparatus are made one-dimensionally, the time delay will occur in which any data transmission is not performed while the response is made to the request. Such time delay results in a decrease in an average transfer speed, which leads to a reduction in the screen updating speed.

[92] In order to prevent this phenomenon, the three-dimensional geographical information server apparatus maintains a plurality of transfer queues (S 1301). In this embodiment, 16 transfer queues are maintained, but not limited thereto. Then, the three-dimensional geographical information client apparatus simultaneously transmits a plurality of data requests to the three-dimensional geographical information server apparatus (S 1302).

[93] In this embodiment, 16 data requests are simultaneously transmitted has been described as an example, but not limited thereto.

[94] The three-dimensional geographical information server apparatus transmits transfer queues to the three-dimensional geographical information client apparatus in the order in which a response to the request is made (S1303), and transmits data to the three- dimensional geographical information client apparatus in the order in which the transfer queues are transmitted (S 1404).

[95] According to the embodiment, since the three-dimensional geographical information server apparatus can perform transmission of an immediate next data without needing to wait for a request for a next transfer queue, the time delay is removed.

[96] FIG. 16 is a flowchart illustrating a process of minimizing mutual data interference upon the application of a multi-thread in a central processor unit (CPU) of a three- dimensional geographical information client apparatus.

[97] In FIG. 16, there is shown a method for minimizing mutual data interference between an update thread and a main thread.

[98] Referring to FIG. 16, a critical section is applied to the update thread (S 1401). The term "critical section" refers to a section of code that accesses a shared resource (data structure or device) that must not be concurrently accessed by a plurality of threads. That is, only the update thread is authorized to access a resource through a step S1401.

[99] The execution of the update thread decompresses a compressed data downloaded from the three-dimensional geographical information server apparatus 300 and updates the decompressed data in a separate space of the memory 550 (S 1402).

[100] Subsequently, the program proceeds to a step S 1403 where the central processing unit determines whether or not the update has been completed. If it is determined at the step S 1403 that the update has not been completed, the program returns to the step S 1402 where the CPU repeatedly performs the following steps. On the other hand, if it is determined at the step S 1403 that the update has been completed, the program proceeds to a step S 1404 where a pointer for the memory where the data has been updated, i.e., an address of the memory where the data has been updated, and a signal indicating completion of the update are transferred to the main thread.

[101] Thereafter, the critical section is applied to the main thread (S1405), and only the main thread is authorized to access a resource. [102] The data is used through the transferred pointer (S 1406). Then, the program proceeds to a step S 1407 where the CPU determines whether or not the use of the data has been completed. If it is determined at the step S 1407 that the use of the data has not been completed, the program returns to the step S 1406 where the CPU repeatedly performs the following steps. On the contrary, if it is determined at the step S 1407 that the use of the data has been completed, the program proceeds to a step S 1408 where a signal indicating the completion of the use of the data is transferred to the update thread.

[103] Using the method as described above, the date interference can be minimized upon the application of the multi-thread.

[104] Although the present invention has been described in connection with the exemplary embodiments illustrated in the drawings, it is only illustrative of a three-dimensional geographical information client apparatus and server apparatus according to the present invention, and a three-dimensional geographical information system including the same, and the present invention is not limited to the embodiments. It will be understood that various equivalent modifications and variations of the embodiments can be made by a person having an ordinary skill in the art without departing from the scope and sprit of the present invention. Therefore, the true technical scope of the present invention should be defined by the appended claims. Industrial Applicability

[105] The present invention can be used in an Internet-based three-dimensional geographical information system which enables improvement of the processing speed of three-dimensional geographical information, utilization of a high-resolution image, and realistic building modeling process.

[106]

Claims

[1] A three-dimensional geographical information client apparatus connected to a tree-dimensional geographical information server apparatus through a network, the three-dimensional geographical information client apparatus comprising: a three-dimensional geographical information generating section for receiving the data stored in the three-dimensional geographical information server apparatus and generating three-dimensional geographical information, wherein the three-dimensional geographical information generating section comprises: a three-dimensional geographical information visualization module for managing data necessary for generating the three-dimensional geographical information; and a data transmitting and receiving module for requesting data from the three- dimensional geographical information server apparatus or receiving data from the three-dimensional geographical information server apparatus, wherein the three-dimensional geographical information visualization module comprises a screen clipping unit for selecting a visible interval seen at an arbitrary view point, the screen clipping unit simultaneously selecting a topographic polygon, a shape object and a model object within the selected visible interval, and wherein the data transmitting and receiving module requests data associated with the topographic polygon, the shape object and the model object selected by the screen clipping unit from the three-dimensional geographical information server apparatus and receives the data from the three-dimensional geographical information server apparatus.

[2] The three-dimensional geographical information client apparatus according to claim 1, wherein the three-dimensional geographical information visualization module further comprises a model object data management unit for managing a request for a model object data stored in the three-dimensional geographical information server apparatus, wherein each model object data within the selected visible interval comprises texture information divided into at least two levels of detail (LoD), and wherein the model object data management unit transfers a request for the model object data having different levels of detail depending on a visible distance or a degree of importance of the model object to the data transmitting and receiving module.

[3] The three-dimensional geographical information client apparatus according to claim 1, wherein the three-dimensional geographical information visualization module further comprises a topographic polygon data management unit for managing a request for a topographic polygon data stored in the three-dimensional geographical information server apparatus, and wherein the topographic polygon data management unit transfers a request for the topographic polygon data whose kinds of a vertex buffer and a bitmap index are the same among the topographic polygon data stored in the three-dimensional geographical information server apparatus to the data transmitting and receiving module.

[4] The three-dimensional geographical information client apparatus according to claim 1, wherein the three-dimensional geographical information visualization module further comprises a shape object data management unit for managing a request for a shape object data stored in the three-dimensional geographical information server apparatus, and wherein the shape object data management unit adds color information to a shape object data transmitted thereto from the three-dimensional geographical information server apparatus, the color information being in the form of a coordinate value of a shared texture for color designation stored in the memory.

[5] The three-dimensional geographical information client apparatus according to claim 1, wherein the data transmitting and receiving module simultaneously makes a plurality of data requests from the three-dimensional geographical information server apparatus.

[6] The three-dimensional geographical information client apparatus according to claim 1, further comprising: a memory for storing data, the memory including the three-dimensional geographical information generating section; a central processor unit for controlling the operation of the three-dimensional geographical information generating section; and a display section for displaying the generated three-dimensional geographical information thereon.

[7] The three-dimensional geographical information client apparatus according to claim 1, wherein the central processor unit processes data in a multi-thread manner, the multi-thread including a network access thread of downloading data requested from three-dimensional geographical information server apparatus, a update thread of updating the downloaded data in the memory, and a main thread of performing a task other than tasks performed in the network access thread and the update thread.

[8] The three-dimensional geographical information client apparatus according to claim 7, wherein the multi-thread establishes a critical section in order to minimize mutual data interference between the respective threads.

[9] A three-dimensional geographical information server apparatus connected to a plurality of three-dimensional geographical information client apparatuses through a network, the three-dimensional geographical information server apparatus comprising: a geographical information database including a topographic polygon data file for storing a topographic polygon data therein, a shape object data file for storing a shape object data therein, and a model object data file for storing a model object data therein; and a web server including a server data retrieving section for retrieve data requested from each of the three-dimensional geographical information client apparatuses from the geographical information database, and a server data transmitting and receiving section for receiving a data request from each of the three-dimensional geographical information client apparatuses, or transmitting the data retrieved by the server data retrieving section to each of the three-dimensional geographical information client apparatuses, wherein the model object data comprises texture information divided into at least two levels of detail (LoD) by each model object.

[10] The three-dimensional geographical information server apparatus according to claim 9, wherein the web server maintains a plurality of transfer queues corresponding to a plurality of data requests simultaneously transmitted thereto from the plurality of three-dimensional geographical information client apparatuses.

[11] The three-dimensional geographical information server apparatus according to claim 9, wherein the topographic polygon data comprises an elevation data and an image data, the image data including a variety of kinds of image data for the same region.

[12] A three-dimensional geographical information system comprising a three- dimensional geographical information server apparatus and a plurality of three- dimensional geographical information client apparatuses which are connected to each other through a network, wherein the three-dimensional geographical information server apparatus comprises: a geographical information database including a topographic polygon data file for storing a topographic polygon data therein, a shape object data file for storing a shape object data therein, and a model object data file for storing a model object data therein; and a web server including a server data retrieving section for retrieve data requested from each of the three-dimensional geographical information client apparatuses from the geographical information database, and a server data transmitting and receiving section for receiving a data request from each of the three-dimensional geographical information client apparatuses, or transmitting the data retrieved by the server data retrieving section to each of the three-dimensional geographical information client apparatuses, wherein the model object data comprises texture information divided into at least two levels of detail (LoD) by each model object, and wherein each of the three-dimensional geographical information client apparatuses comprises a three-dimensional geographical information generating section for receiving the data stored in the three-dimensional geographical information server apparatus and generating three-dimensional geographical information, a memory for storing data, the memory including the three-dimensional geographical information generating section, and a central processor unit for controlling the operation of the three-dimensional geographical information generating section, wherein the central processor unit processes data in a multi-thread manner, the multi-thread includes a network access thread of downloading data requested from three-dimensional geographical information server apparatus, a update thread of updating the downloaded data in the memory, and a main thread of performing a task other than tasks performed in the network access thread and the update thread.