An auxiliary method for bridge site selection based on BIM and GIS

Abstract

The present invention discloses a bridge location selection auxiliary method based on BIM and GIS, including: data measurement step, BIM model establishment step, GIS model establishment step, model comparison processing step, model coupling step, bridge location selection simulation step. The present invention couples the geographic spatial location data of three models, namely, the bridge BIM model, the three-dimensional GIS model of the bridge surrounding environment and the bridge surrounding environment BIM model, and integrates the accuracy of the BIM model and the authenticity of the GIS model, thereby forming a three-dimensional sand table model with comprehensive geographic data and bridge component information. This three-dimensional sand table model can assist designers in making scientific judgments and accurate decisions, thereby improving design work efficiency, reducing engineering costs and safety risks, and ensuring the safety and stability of the bridge. Compared with the traditional bridge location selection method, this method is more intelligent and more scientific, and will greatly improve the efficiency of bridge design, further ensuring the safety and economy of the bridge.

Description

Technical Field

[0001] The present invention relates to the field of bridge engineering, and in particular to a bridge location selection auxiliary method based on BIM and GIS. Background Art

[0002] In the early design of bridge engineering, the selection of bridge site is a crucial link. Bridge site selection mainly refers to the selection of the bridge's crossing river location based on basic information. This process not only directly affects the safety, stability, service life and technical and economic rationality of the bridge structure engineering, but also involves the convenience and feasibility of construction and management and maintenance.

[0003] The inventor of this patent discovered at least the following technical problems in the prior art during the process of implementing a bridge location selection auxiliary method based on BIM and GIS in an embodiment of the present invention:

[0004] First, the selection of bridge locations often relies too much on traditional experience and intuitive judgment, lacking scientificity and precision. This may result in the selected bridge location not meeting actual engineering requirements and may even cause safety hazards.

[0005] Secondly, the existing preliminary design of bridges often does not fully consider environmental factors and ecological impacts when selecting bridge locations. For example, some bridge locations may be located in ecologically sensitive areas, and the selection of these bridge locations may cause damage to the local ecological environment. In addition, the selection of bridge locations should also consider multiple factors such as geological conditions, climatic conditions, and hydrological conditions to ensure the safety and stability of the bridge.

[0006] Third, the existing bridge preliminary design lacks comprehensive consideration and optimization capabilities when selecting bridge locations. In actual projects, bridge location selection often needs to consider the comprehensive impact of multiple factors, including project cost, construction difficulty, bridge performance, etc. However, the existing bridge location selection technology can only consider a single factor, and cannot achieve comprehensive optimization of multiple factors.

[0007] Finally, the bridge site selection lacks automation and intelligence. With the continuous advancement of science and technology, more and more fields are beginning to apply automation and intelligent technologies. However, in the field of bridge engineering, the automation and intelligence level of bridge site selection is still low, which may lead to low work efficiency and increase the risk of errors.

[0008] In summary, the existing bridge site selection method cannot meet actual needs. Summary of the invention

[0009] The embodiment of the present invention provides a bridge site selection auxiliary method based on BIM and GIS, which solves the problem that the existing bridge site selection method cannot meet actual needs.

[0010] The embodiment of the present invention provides a bridge location selection auxiliary method based on BIM and GIS, including:

[0011] Data measurement step: obtaining influencing factor data related to the selection of bridge location in the preliminary design of the bridge, and drawing a parameter 2D plane diagram based on the influencing factor data;

[0012] Steps for establishing a BIM model: creating a BIM model of the surrounding environment of the bridge based on the parametric 2D parametric plan; creating a BIM model of the bridge according to the bridge design drawings;

[0013] Steps to establish the GIS model: Use the UAV oblique photography method to collect GIS data of the bridge surrounding environment and build a three-dimensional GIS model of the bridge surrounding environment;

[0014] Model comparison processing steps: accurately process the differences between the BIM model and the GIS model, and reassign the materials in the BIM model;

[0015] Model coupling step: seamlessly connect and integrate the attributes of the BIM model and the GIS model to complete the model coupling and form a three-dimensional sandbox model with complete geographic information;

[0016] Bridge location selection simulation steps: In the three-dimensional sandbox model, import the BIM models of various types of bridges to be selected, accurately measure the distances of key locations, and simulate the bridge routes. By comparing the actual effects of various types of bridges in different locations to determine their impact, the designers are assisted in selecting the optimal design solution.

[0017] Optionally, the obtaining of the influencing factor data related to the bridge location selection in the preliminary bridge design is specifically:

[0018] Manual measurement is used to measure the data of influencing factors related to bridge location selection in the early stage of bridge design.

[0019] Optionally, the influencing factor data include spatial parameter information of artificial buildings around the project, surrounding terrain elevation information, hydrological information, geological information, relevant road information, and relevant railway location information.

[0020] Optionally, drawing a parameter 2D plane diagram based on the influencing factor data specifically includes:

[0021] Based on the influencing factor data, a parametric 2D plane diagram including the influencing factor data is drawn using CAD.

[0022] Optionally, the creating a BIM model of the surrounding environment of the bridge based on the parametric 2D parametric plane map is specifically:

[0023] Based on the parametric 2D parametric plan, a BIM model of the bridge surrounding environment is created using Revit software.

[0024] Optionally, creating a BIM model of the bridge surrounding environment based on the parametric 2D parametric plane map specifically includes:

[0025] Create artificial building models based on parameters in 2D parametric floor plans;

[0026] Create a geohydrological model based on geological and hydrological information;

[0027] Draw a three-dimensional terrain model based on the surrounding terrain elevation information;

[0028] Based on the artificial building model, the geological and hydrological model and the three-dimensional terrain model, a BIM model of the bridge surrounding environment containing various information is finally formed.

[0029] Optionally, the step of establishing a GIS model specifically includes:

[0030] The GIS data of the surrounding environment of the bridge is collected by using the UAV oblique photography method, and the GIS data of the surrounding environment of the bridge is processed by using the ContextCapture software to construct a three-dimensional geographic model;

[0031] Input photos with GIS information into the ContextCapture software, perform aerial triangulation and model reconstruction calculations, and output a three-dimensional GIS model of the bridge's surrounding environment.

[0032] Optionally, the model comparison processing step specifically includes:

[0033] Import BIM model and GIS model into 3DMax for interactive comparison;

[0034] The BIM model is processed in 3DMax. The materials in the BIM model need to be reassigned and the OSGB format file is output through 3DMax software.

[0035] The GIS model outputs the OSGB format file, which is imported into DJI Intelligent Modeling Software for processing and outputs the OSGB file format;

[0036] Obtain the BIM model and GIS model after precise processing.

[0037] Optionally, the BIM model and the GIS model are imported into 3DMax for interactive comparison, specifically including:

[0038] Flatten, delete or replace the fuzzy fragments in the GIS model with the BIM model;

[0039] When the relative positions of models in the BIM model do not match the actual positions, adjustments should be made based on the GIS model.

[0040] Optionally, the model coupling step specifically includes:

[0041] Import the GIS model of the model comparison processing step into the DasViewer software;

[0042] To unify the coordinate system, copy the Metal.xml format file in the GIS model file obtained in the GIS model establishment step to the BIM model file in the model comparison processing step, and then import the BIM model into the DasViewer software;

[0043] Based on the corresponding elements of the two, the BIM model and the GIS model are connected to achieve seamless connection and attribute integration of the BIM model and the GIS model, so as to complete the model coupling and form a three-dimensional sand table model with complete geographic information.

[0044] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0045] The present invention establishes a BIM model of the surrounding environment of the bridge based on the accuracy of BIM, and interactively compares the BIM model of the surrounding environment of the bridge with the three-dimensional GIS model of the surrounding environment of the bridge, and replaces the fuzzy fragments that may exist in the GIS model with a more accurate BIM model, thereby improving the accuracy of the GIS model; the present invention creates a three-dimensional GIS model of the surrounding environment of the bridge based on the authenticity of GIS, and interactively compares the three-dimensional GIS model of the surrounding environment of the bridge with the BIM model of the surrounding environment of the bridge, thereby solving the problem that the relative position of the model in the BIM model does not match the actual position, thereby improving the authenticity and accuracy of the BIM model; by coupling the geographic spatial position data of the three models of the BIM model of the bridge, the three-dimensional GIS model of the surrounding environment of the bridge and the BIM model of the surrounding environment of the bridge, the accuracy of the BIM model and the authenticity of the GIS model are integrated, thereby forming a three-dimensional sand table model with comprehensive geographic data and bridge component information. This three-dimensional sandbox model can intuitively reflect the data interaction information of bridge engineering and surrounding environmental conditions. Bridge designers can retrieve the key information needed for bridge site selection at any time, assisting designers to make scientific judgments and accurate decisions, thereby improving design work efficiency and reducing engineering costs and safety risks; data coupling of various models allows designers to comprehensively consider various factors, such as construction difficulty, geological conditions and bridge performance, so as to optimize bridge design and ensure bridge safety and stability. Compared with the traditional bridge site selection method that relies on its own experience, plan drawings and various engineering data, this method is more intelligent and scientific, and will greatly improve bridge design efficiency and further ensure the safety and economy of bridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of a bridge location selection auxiliary method based on BIM and GIS in one embodiment of the present invention;

[0047] Figure 2 A BIM model diagram of a bridge and its surrounding environment in one embodiment of the present invention;

[0048] Figure 3 It is an unprocessed GIS model diagram in one embodiment of the present invention;

[0049] Figure 4 It is a GIS model diagram after precision processing in one embodiment of the present invention;

[0050] Figure 5 Schematic diagram of a coupling model in one embodiment of the present invention. DETAILED DESCRIPTION

[0051] The embodiment of the present invention provides a bridge site selection auxiliary method based on BIM and GIS, which solves the problem that the existing bridge site selection method cannot meet actual needs.

[0052] First, the terms that appear in the specification will be explained respectively.

[0053] 1. BIM

[0054] BIM (Building Information Modeling) is a virtual building built in a computer through digital means. The virtual building will provide a single, complete, and logically related building information library. It should be noted that the connotation of "information" here is not only the visual information described by geometric shapes, but also includes a large amount of non-geometric information, such as the fire resistance level and heat transfer coefficient of materials, the cost and procurement information of components, etc. Its essence is a database built according to the intuitive physical form of the building, which records all data information at each stage.

[0055] BIM is a building model that is built based on various relevant information data of the project. It simulates the real information of the building through digital information simulation.

[0056] BIM is an integrated process built on the basis of design, construction, operation coordination and project information. It has five major characteristics: visualization, coordination, simulation, optimization and map-ability. By using BIM, unified information can be innovated, designed and mapped out throughout the process. It can also be better communicated through realistic simulation and architectural visualization, so that all parties involved in the project can understand basic project information such as construction period, real-time on-site conditions, cost and environmental impact.

[0057] 2. GIS

[0058] GIS (Geographic Information System) is a new technology developed in the mid-1960s. It is a computer system for collecting, processing, storing, querying, analyzing and displaying spatial information on the earth's surface. It is a comprehensive spatial information system that integrates spatial data and attribute data based on computer graphics and image processing, database technology, surveying and mapping remote sensing technology and modern mathematical research methods. Due to its unique advantages in spatial information management and analysis, it has been widely used in many fields. In the engineering field, the GIS system can be used to integrate the visual effects of maps with the analysis of geographic information, and to perform a series of digital statistical management and processing of geographical distribution data, thereby realizing the overall management and control of construction projects.

[0059] 3. Integration of BIM and GIS

[0060] BIM and GIS are two different technologies, both of which have their own characteristics. The original intention of integrating BIM technology with GIS technology is to integrate the advantages of the two technologies, let the two complement each other, and empower digitalization and intelligence in various fields, especially in the engineering field. The integration of BIM and GIS is fundamentally the integration of two different data.

[0061] The integration of BIM and GIS is to establish the connection between the micro-model information of each component of the building and structure and the external geographical macro-information. Taking the bridge project as an example, the BIM model of the bridge itself is the BIM data, and the terrain model of the proposed bridge area obtained through drone oblique photography can be regarded as GIS data. The terrain model shows a large range of geographical space and the geographical location relationship between each element in this space, which is macro information; while the model of the bridge itself expresses the detailed information of each component of the bridge, which belongs to the micro-model information. The organic integration of the bridge BIM model and the oblique photography terrain model around the proposed bridge area in terms of geographical space information through GIS software, and the corresponding application on this basis is the integrated application of BIM and GIS.

[0062] 4. Revit software

[0063] Revit software is a building information modeling (BIM) software developed by Autodesk. With its powerful 3D modeling capabilities, information integration characteristics and collaborative design functions, it plays an important role in the fields of construction, infrastructure and equipment engineering. It not only improves design efficiency and quality, but also promotes communication and collaboration among all project participants, providing strong support for innovation and development in the construction industry.

[0064] 5. ContextCapture

[0065] ContextCapture is a real scene modeling software from Bentley Software that can process various data sources, including images and point cloud data collected from drones, aircraft or ground photogrammetry systems, as well as photos taken by ordinary cameras. It has the characteristics of high compatibility, automated modeling, high precision, and multi-field application. It provides users with a complete solution from data collection to 3D model generation, and is widely used in many fields such as urban planning, cultural heritage protection, and game development.

[0066] 6. 3DMax

[0067] 3DMax, the full name of 3D Studio Max, is a PC-based 3D modeling, rendering and production software developed by Autodesk. The main features of 3DMax include: a wide range of applications, powerful modeling functions, rich material and lighting settings, animation settings and rendering. 3DMax is a powerful and widely used 3D design software that plays an important role in the fields of 3D modeling, rendering and animation production.

[0068] 7. DJI Intelligent Modeling Software

[0069] DJI Smart Model is the first intelligent 3D model editing software launched by DJI (DJI Innovations). The software is designed to simplify the modification of 3D models. With its simple and easy-to-use, powerful functions, high efficiency and intelligence, it provides great convenience for users in surveying and mapping, firefighting, emergency response, transportation and other fields, improves the efficiency and accuracy of model editing, and meets the operational needs of surveying and mapping, firefighting, emergency response, transportation and other fields.

[0070] 8. DasViewer software

[0071] DasViewer software is a powerful and easy-to-use real-life 3D model browser independently developed by Dashi Wisdom. It uses multi-level model gradual adaptive loading technology, which can smoothly load large-scale real-life 3D models under extremely low computer configuration, and provide convenient and fast data browsing operations. It has the characteristics of efficient loading and convenient operation, fast response, multi-tile selection, annotation function, multiple display modes, path roaming high-definition video output, light source adjustment, 3D measurement, dual-screen browsing, and progress inspection. It is suitable for various scenes that need to browse and edit real-life 3D models.

[0072] In order to better understand the auxiliary method for bridge location selection based on BIM and GIS in the embodiment of the present invention, a detailed description will be given below in conjunction with the drawings and specific implementation methods of the specification. Obviously, the embodiment described in the present invention is a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0073] like Figure 1 As shown, a bridge site selection auxiliary method based on BIM and GIS includes: data measurement step, BIM model establishment step, GIS model establishment step, model comparison processing step, model coupling step and bridge site selection simulation step.

[0074] Data measurement steps: Obtain the influencing factor data related to the bridge location selection in the preliminary design of the bridge, and draw a parametric 2D plan based on the influencing factor data.

[0075] In specific implementation, for example: in the preliminary design of the bridge, the influencing factors related to the selection of the bridge site include hydrological conditions, topography, geological conditions, and economic and environmental protection performance. The influencing factor data are obtained by measuring the above influencing factors, and based on the influencing factor data, a parametric 2D plane diagram is drawn using graphics processing software.

[0076] The data of influencing factors related to the selection of bridge position in the preliminary design of the bridge are obtained, specifically: the data of influencing factors related to the selection of bridge position in the preliminary design of the bridge are measured by manual measurement. Of course, in practical applications, other measurement methods can be used, such as drone aerial photography, WeChat remote sensing, etc., which are not limited by the present invention.

[0077] The influencing factor data includes the spatial parameter information of artificial buildings around the project, the surrounding terrain elevation information, hydrological information, geological information, relevant road information, and relevant railway location information.

[0078] Drawing a parametric 2D plane diagram based on the influencing factor data specifically includes: drawing a parametric 2D plane diagram containing the influencing factor data using CAD based on the influencing factor data. Of course, in practical applications, other graphics processing software, such as AutoCAD LT, CorelDRAW, etc., can be used, and the present invention does not limit this.

[0079] Please also refer to Figure 1 and Figure 2 , Steps to establish the BIM model: Create a BIM model of the bridge surrounding environment based on the parametric 2D parametric plan; Create a BIM model of the bridge according to the bridge design drawings.

[0080] Among them, based on the parametric 2D parametric plan view, a BIM model of the surrounding environment of the bridge is created. Specifically, based on the parametric 2D parametric plan view, the BIM model of the surrounding environment of the bridge is created using Revit software.

[0081] Based on the parametric 2D parametric plan, a BIM model of the bridge's surrounding environment is created, specifically including: creating an artificial building model according to the parameters in the 2D parametric plan; creating a geological and hydrological model according to geological information and hydrological information; drawing a three-dimensional terrain model according to the surrounding terrain elevation information; and finally forming a BIM model of the bridge's surrounding environment containing various information based on the artificial building model, the geological and hydrological model and the three-dimensional terrain model.

[0082] Model files can be exported in multiple formats such as FBX, rvt, etc.

[0083] Steps to establish the GIS model: Use drone oblique photography to collect GIS data of the bridge's surrounding environment and build a three-dimensional GIS model of the bridge's surrounding environment.

[0084] The steps of establishing the GIS model include: using the drone oblique photography method to collect GIS data of the bridge's surrounding environment, using the ContextCapture software to process the GIS data of the bridge's surrounding environment, and constructing a three-dimensional geographic model; inputting photos with GIS information into the ContextCapture software, performing aerial triangulation calculations and model reconstruction calculations, and then outputting a three-dimensional GIS model of the bridge's surrounding environment.

[0085] Model files can be exported in various formats such as OBJ, OSGB, etc.

[0086] Model comparison processing steps: accurately process the differences between the BIM model and the GIS model, and reassign the materials in the BIM model.

[0087] Since the BIM model and GIS model in the BIM model establishment step and the GIS model establishment step may be different from the actual environment, it is necessary to compare and analyze these two models so that the three-dimensional sand table models presented by the two in the subsequent model coupling step will be more accurate.

[0088] The BIM model is exported as an FBX format model file through Revit software, and the GIS model is exported as an OBJ format model file through ContextCapture software.

[0089] The model comparison processing steps specifically include: importing the BIM model and GIS model into 3DMax for interactive comparison; processing the BIM model in 3DMax, reassigning the materials in the BIM model, and outputting the OSGB format file through 3DMax software; importing the GIS model output OSGB format file into DJI Smart Model software for processing, and outputting the OSGB file format; obtaining the BIM model and GIS model after precision processing. For the GIS model diagram before and after precision processing, please refer to Figure 3 and Figure 4 .

[0090] The BIM model is exported as an OSGB format file through the 0SGB-MAX toolbox plug-in in the 3DMax software.

[0091] In order to deal with the differences between the BIM model and the GIS model, the BIM model and the GIS model are imported into 3DMax for interactive comparison, including: flattening, deleting or replacing the fuzzy fragments in the GIS model with the BIM model; when the relative positions of each model in the BIM model do not match the actual positions, adjustments are made according to the GIS model.

[0092] like Figure 5As shown, the model coupling steps are: seamless docking and attribute integration of BIM model and GIS model to complete model coupling and form a three-dimensional sandbox model with complete geographic information.

[0093] The model coupling step specifically includes: importing the GIS model of the model comparison processing step into the DasViewer software; in order to unify the coordinate system, copying the Metal.xml format file in the GIS model file obtained in the GIS model establishment step into the BIM model file in the model comparison processing step, and then importing the BIM model into the DasViewer software; based on the corresponding elements of the two, docking the BIM model and the GIS model to achieve seamless docking and attribute integration of the BIM model and the GIS model, so as to complete the model coupling and form a three-dimensional sand table model with complete geographic information.

[0094] Bridge location selection simulation steps: In the 3D sandbox model, import the BIM models of various types of bridges to be selected, accurately measure the distances of key locations, and simulate the bridge routes. By comparing the actual effects of various types of bridges in different locations, their impacts can be judged, thereby assisting designers in selecting the optimal design solution.

[0095] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A bridge site selection auxiliary method based on BIM and GIS, characterized in that: include: Data measurement step: obtaining influencing factor data related to the selection of bridge location in the preliminary design of the bridge, and drawing a parameter 2D plane diagram based on the influencing factor data; Steps for establishing a BIM model: creating a BIM model of the surrounding environment of the bridge based on the parametric 2D parametric plan; creating a BIM model of the bridge according to the bridge design drawings; Steps to establish the GIS model: Use the UAV oblique photography method to collect GIS data of the bridge surrounding environment and build a three-dimensional GIS model of the bridge surrounding environment; Model comparison processing steps: accurately process the differences between the BIM model and the GIS model, and reassign the materials in the BIM model; Model coupling step: seamlessly connect and integrate the attributes of the BIM model and the GIS model to complete the model coupling and form a three-dimensional sandbox model with complete geographic information; Bridge location selection simulation step: importing various types of bridge BIM models to be selected into the three-dimensional sandbox model, accurately measuring the distance of key positions, and simulating the bridge route, and comparing the actual effects of various types of bridges at different positions to determine their impact, thereby assisting designers in selecting the best design solution; The model comparison processing step specifically includes: Import BIM model and GIS model into 3DMax for interactive comparison; The BIM model is processed in 3DMax. The materials in the BIM model need to be reassigned and the OSGB format file is output through 3DMax software. The GIS model outputs the OSGB format file, which is imported into DJI Intelligent Modeling Software for processing and outputs the OSGB file format; Obtain the BIM model and GIS model after precise processing; The importing of BIM model and GIS model into 3DMax for interactive comparison specifically includes: Flatten, delete or replace the fuzzy fragments in the GIS model with the BIM model; When the relative positions of models in the BIM model do not match the actual positions, adjustments should be made based on the GIS model.

2. The method according to claim 1, characterized in that The data of influencing factors related to the selection of bridge location in the preliminary design of the bridge are obtained as follows: Manual measurement is used to measure the data of influencing factors related to bridge location selection in the early stage of bridge design.

3. The method according to claim 1, characterized in that The influencing factor data include spatial parameter information of artificial buildings around the project, surrounding terrain elevation information, hydrological information, geological information, relevant road information, and relevant railway location information.

4. The method according to claim 1, characterized in that Drawing a parameter 2D plane diagram based on the influencing factor data specifically includes: Based on the influencing factor data, a parametric 2D plane diagram including the influencing factor data is drawn using CAD.

5. The method according to claim 1, characterized in that The creation of a BIM model of the surrounding environment of the bridge based on the parametric 2D parametric plane map is specifically as follows: Based on the parametric 2D parametric plan, a BIM model of the bridge surrounding environment is created using Revit software.

6. The method according to claim 3, characterized in that The creating of the bridge surrounding environment BIM model based on the parametric 2D parametric plane map specifically includes: Create artificial building models based on parameters in 2D parametric floor plans; Create a geohydrological model based on geological and hydrological information; Draw a three-dimensional terrain model based on the surrounding terrain elevation information; Based on the artificial building model, the geological and hydrological model and the three-dimensional terrain model, a BIM model of the bridge surrounding environment containing various information is finally formed.

7. The method according to claim 1, characterized in that The steps of establishing the GIS model specifically include: The GIS data of the surrounding environment of the bridge is collected by using the UAV oblique photography method, and the GIS data of the surrounding environment of the bridge is processed by using the ContextCapture software to construct a three-dimensional geographic model; Input photos with GIS information into the ContextCapture software, perform aerial triangulation and model reconstruction calculations, and output a three-dimensional GIS model of the bridge's surrounding environment.

8. The method according to claim 1, characterized in that The model coupling step specifically includes: Import the GIS model of the model comparison processing step into the DasViewer software; To unify the coordinate system, copy the Metal.xml format file in the GIS model file obtained in the GIS model establishment step to the BIM model file in the model comparison processing step, and then import the BIM model into the DasViewer software; Based on the corresponding elements of the two, the BIM model and the GIS model are connected to achieve seamless connection and attribute integration of the BIM model and the GIS model, so as to complete the model coupling and form a three-dimensional sand table model with complete geographic information.

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