Scientific Journal of Earth Science June 2014, Volume 4, Issue 2, PP.140-145
Design and Implementation of 3D Virtual Campus ——A Case Study of Shandong JianZhu University Hao Liu 1#, Zimin Zhang2, Ying Zhou 2 1. School of Transportation Engineering, Shandong Jianzhu University, Shandong 250101, China 2. Department of Civil Engineering, Shandong Jianzhu University, Shandong 250101, China #
Email: Liuhaoo@yeah.net
Abstract Three-dimensional virtual campus is a hot shot in current digital campus construction, and will become a new platform to support campus information management in the future. Thematic data involved in three - dimensional virtual campus also with many layers, complex structure and difficult construction. The paper analyses the current techniques of three-dimensional modeling systematically, especially the accuracy of model and the appropriate spatial scale. Selected a modeling program meets the virtual campus and designed the acquisition and integration methods of the thematic data layers for three-dimensional virtual campus, formed technical processes of building a three-dimensional virtual campus. We took Shandong Jianzhu University as a case threedimensional modeled architecture, the Vegetation and water, transportation and underground pipelines and other monomers respectively. By integrating thematic layers and attribute information created a three-dimensional virtual campus of Shandong Jianzhu University, verified the feasibility of the methods proposed and the technical processes. Keywords: 3D Virtual Campus; 3D Modeling; 3D Virtual Environment; Virtual Reality
1 INTRODUCTION Since the basic idea of virtual reality proposed in 1965 virtual reality technology has been rapid developed. U.S. first make use of VR technology in the military field; Britain in a leading position in the parallel processing, applied research and auxiliary equipment design in Europe; Japan targeted the construction of large-scale virtual reality knowledge-base and virtual reality games. In China, the field of virtual reality is still in the exploration and technical track stage, some domestic colleges and universities have also established a virtual reality system or a virtual campus but did not get good practical effect. Virtual campus construction overall still remain in the original software and hardware construction and there’s no substantial breakthrough. The research and application based on threedimensional virtual reality campus has great potential. Construction of virtual campus in foreign countries has achieved virtualized completely while in China it generally dependent on physical campus. On the construction of digital campus in foreign countries focuses on open educational management while the current focus in domestic is on campus cultural awareness and 2D and 3D interface display.[1] Campus as an important part of urban culture, it plays an important role in building an ecological city, reflecting the geographical features and heritage campus Culture Root. To build a harmonious coexistence between man and nature and picturesque campus environment with a profound cultural heritage has become the primary target in planning and construction of campus. Meanwhile the digital campus is an important part of the digital city. Many universities have established their campus geographic information system (GIS) along with the widely adoption of information technologies, which have played an important role in the campus management. These systems are usually two-dimensional, and have difficulty to depict the campus truly and intuitively despite of their useful functions. With the spread of virtual geographic environment technology, 3D GIS and virtual realistic techniques are used more and more extensively in campus GIS. In other countries the earlier VRGIS system is the Georgia Institute of Technology’s campus GIS. Its supporter and developer Faust also described a perfect campus with characteristics that VRGIS should have.[2] The 3D scene - 140 http://www.j-es.org
replaces the abstract symbols of traditional map with the view of 3D features and terrain, so that the map goes beyond the original and traditional category of geography space information. The 3D virtual campus system making a vivid view of the campus scene provides a 3D platform for digital campus. The 3D campus model can reappear the whole campus in computers virtually and inside which we can observe the outlook of campus buildings, examine the layout and space design.[3] The system provides a scientific and simple visual human-computer-interaction platform for the campus management and service.[4]
2 METHODS OF 3D MODELING Modelling natural and artificial features in campus is an important foundational work of 3D virtual campus. At present, several methods are developed and utilized with the help of modern survey and map technique. They are different in the quality and accuracy of resulted model, as well as the suitable scope.
2.1 The Digital Photogrammetric Technique Using the digital photogrammetric technique has significant advantages with the characteristics of perfect accuracy and high modelling speed especially suitable for wide-range 3D modelling.[5] For example, Xiaojun Cheng and Zhu Li from Tongji University once made the 3D model for a campus and its periphery utilizing this method. However this method is more applicable to a wider range of three-dimensional modelling such as the establishment of digital city. It is difficult to use in establishing a three-dimensional model of the campus because the high price of the system equipment.
2.2 The Laser Scanning Technique With the laser scanning technique, original multi-view point cloud data of different building surfaces are obtained by laser scanning, and further matched and filtered. Get the point cloud data required for three-dimensional modelling of buildings surface. Then make a three-dimensional model of the building according to each separate part of the building with the point cloud data processed.[6] A case is the digital campus of Tsinghua University, which is implemented by the Earth Space Information Institution of the Civil Engineering Department. In this work, a laser scanner with huge inclination angle is used to scan the campus from the sky then the 3D point cloud data of buildings and terrain are obtained. Processing and analysis the buildings’ and terrain’s three-dimensional point cloud data obtained, Sketching the wire frames of buildings, rendering the model after attach the material, then forming a three-dimensional model.[7] However when the techniques used in three-dimensional modelling the campus the fine is not enough, and the side texture is costly and difficult to obtain comprehensive.
2.3 Using 3D GIS Softwares With the development of digital city, 3D GIS have become a hotspot of GIS. Some GIS software have provided a series of 3D modelling modules suitable for different applications, such as modelling earth's surface scene, modelling the cities and modelling the geologic structures.[8] In these softwares, 3D models are usually established by stretching according to 2D profile lines and DEM. Therefore, this method is suitable for the rapid modelling of features in brief, for example the building box models, but it is difficult to the features with complicated surfaces.
2.4 3D Modelling Software Presently the 3D modelling softwares are very mature. We can make very vivid feature models and accurately express the materials and fine structures of features using them. The three-dimensional model we get is close to reality completely. Especially when making the models of some irregular structure (such as bridge, arbour, dome and tower-like buildings) and natural features (such as tree and lake) this method has obvious advantage. Threedimensional software has a lot of ancillary facilities model, such as trees, green belts, single building, etc. simplifying the workload of the modelling greatly.[9]
3 DESIGN AND IMPLEMENTATION OF 3D VIRTUAL CAMPUS The area of campus is small and the features of campus are usually complicated such as roads, apartments, - 141 http://www.j-es.org
playgrounds, infrastructure, landscape, etc. but the accuracy requirement of models is high. Therefore it is reasonable to select 3D modelling software to build virtual campus. In this case, 3Ds MAX is utilized to make 3D models and paste the corresponding texture on the corresponding building model. The GIS software ArcGIS is used as the 3D scene integration platform.
3.1 Technique Process 3D virtual campus consists of multiple information layers, the key layers in which include 3D feature models, DEM and image. In addition, 2D vector layers can also be overlaid according to requirements. Campus plan and design maps are the important data sources to 3D feature modelling. DEM and image layers constitute the 3D scene model together. According to these characteristics, a technique process for implementation of 3D virtual campus is designed as shown in figure 1. Campus map
Image
Layer Extraction
Attribution information
DEM
Integrat e Coding build database
Feature layer 3D landscape models
3D Modelling
Attribute database
Monomer structure model Integrate Texture mapping and rendering
Feature model
Integrate
3D virtual campus
Integrate
FIG. 1 THE TECHNICAL PROCESS OF 3D VIRTUAL CAMPUS
1) Obtain and process data. Main data obtained include the plan map, high resolution images, the contour line map or DEM, and related attribute data of features, for example the name, age and accommodated departments of a building. From the plan map, some feature layers are abstracted including buildings, water and vegetation, transportation facilities and underground pipelines. 2) Make feature models. The 3D structure models of abstracted features are built respectively according to feature layers with the 3D modelling software. Then take pictures of different monomers facade with a camera. After image processing and cutting, form the texture about size of 128×128 or 256×256. Then map onto the Monomer structure model. Finally set uniform lighting for all feature model for rendering. 3) Make 3D landscape model. Take use of scene integrate software to integrate the campus’ image and DEM and create a three-dimensional model of the campus landscape. 4) Create attribute database to collect information on campus attribute corresponding to each single layer and give them a unified coding. Establish the campus’ attribute information database with scene integrate software. 5) Integrate 3D virtual campus. Integration the feature model and 3D landscape models as well as attribute information to constitute a three-dimensional virtual campus. The feature models with independent elevation information can be added on the 3D scene model as independent layers directly, otherwise it will as the form of a floating layer added on the 3D scene model. Feature models are associated with attribute information by consistent coding.
3.2 Modelling Features 1) Building. The buildings are the main body of 3D virtual campus with the largest workload. In order to achieve a better realistic effect, intensive modelling method should be adopted when process buildings. All structure surfaces bigger than 0.5 meters should be modelled while others can be expressed by texture pictures. All the texture pictures - 142 http://www.j-es.org
are real view photographs, and processed by colour balance and stain removal. Arcuate building’s wall requires the use of projection mapping, otherwise the textures will be deformed. It will not achieve the desired results.[10] Figure 2a is an example of a building’s 3D model generated with the method above. 2) Transportation facilities. The transportation facilities in campus mainly include sidewalk, roadway, signpost, street lamp and stand hall, etc. The main body of transportation models is sidewalk and roadway. For a more realistic expression and reflect of the different functions of the road, universal texture images should be combined with texture pictures from real view photographs when select the materials and textures for the road surface. Select or make a high degree of similarity with the actual materials as texture. For other facilities, 3D symbols can be used to express them. For the key sections, create realistic models based on the actual style. Figure 2b gives a road model example. 3) Vegetation and water. Vegetation includes forest, wayside green trees and independent trees such as ancient trees and scenery trees. The count of the patches of a 3D tree fine model is very large generally from thousands to tenthousands. To simplify the modelling method can use cross-patch form, the model just need several surface and the shape of the tree can be expressed by textures. It is suitable to use the simplified modelling method when modelling the forest and wayside trees, the cropping patterns can be piece and rows planted. To the scenery trees and ancient trees a fractal method is utilized to establish the fine models. We can select similar trees from the model database, or use other method to create tree models manually. Additionally, the three-dimensional modelling capabilities of ArcGIS can further simplify the process by the method chip planted and rows planted. The specific method is render two-dimensional layer of vegetation with the selected trees in the form of a three-dimensional model of symbols. For the lawn and water, patches with texture are used to express them. Figure 2c a combination of a simplified and fine model of trees. 4) Underground pipeline. Build a three-dimensional model of the underground pipe network can help to manage the pipelines and ancillary facilities as well as planning and design of new pipeline in campus greatly. Limited by the data the case study only modelled the water supply network for the campus, focused on the supply line and its interface. Figure 2d is a part of the pipeline model created.
(a) A BUILDING MODEL
(b) ROAD MODELS
(c) VEGETATION MODELS
(d) UNDERGRAND PIPELINE MODELS
FIG. 2 THE 3D FEATURE MODELS
3.3 Integration of 3D Virtual Campus ArcGIS is one of the most extremely perfect geographic information platforms, which also provides a threedimensional geographic information features and software, including ArcScene and ArcGlobe. ArcScene is suitable for three-dimensional modelling the small areas, such as a campus and ArcGlobe is applicable to a wide range of - 143 http://www.j-es.org
area such as city, region and so on. In ArcScene, a three-dimensional scene usually consists of three parts, terrain, images, models and vector layers. Terrain can be the TIN or raster format providing ground elevation information for other layers as the basic layer. Superimpose terrain layer on the image to obtain the elevation data for each pixel and then present real surface view. Model and vector layers are used to express a variety of surface features. They can determine their placement height with the Z coordinate values stored or superimpose to place on the terrain layer. In addition, we can also integrate the attribute information of the features with the model and vector graphics by associating operation. Besides the creation of three-dimensional scene, ArcScene also offers a lot of threedimensional manipulation and analysis functions including vertical stretch the layer, three-dimensional animation production and playback, scene’s backgrounds and lighting effects settings and so on. The software ArcScene is selected to integrating the 3D virtual campus. Firstly, overlay the campus images onto the DEM as a floating layer. DEM acts as the original elevation source to provide the heights for each pixel of the images. Then integrate the feature models onto the scene model as overlay-layers one by one. As the each feature model consists a elevation information, it can display on the landscape model independently. It is necessary for the feature’s attribute information to get a unified coding in order to support the management and multi-user concurrent operation of the spatial data.[11] As showed in Figure 3 the code designed comprises 6 digits. The first two digits delegate the type of features, such as JZ represents the buildings. The last four digits stand for the order code which increases continuously along with the data input sequence, such as JZ0003 stands for the third inputted building. Type Code （two digits）
Order code （four digits）
Building: JZ Water: ST Underground pipeline: GW Vegetation: ZB Transportation facilities: JT
FIG. 3 THE ATTRIBUTE CODING SCHEME
According to the coding rule above, a corresponding code is added to the attribute record and the feature model at the same time. Then take the use of attribute associated function to establish the correspondence between models and attribute. In this way corresponding attribute information can be found when check the model, and model will be selected when check through the corresponding attribute.
3.4 The Results Demonstrate The designed Shandong Jianzhu University’s three-dimensional virtual campus to achieve a information inquiry function when a Feature selected as goals in the map, the basic information about the target will displayed in the GIS interface. Furthermore it can also inquiry when enter the destination information via a query window. The results Queried will become highlighted feature goals in the figure. The 3D virtual campus for Shandong Jianzhu University
(a) TEACHING ZONE
(b) QUERY ATTRIBUTES
FIG. 4 THE 3D VIRTUAL CAMPUS OF SHANDONG JIANZHU UNIVERSITY - 144 http://www.j-es.org
is created based on the work above. Figure 4a gives a scene of the teaching zone, the layer integrated include DEM, images and feature (buildings, meadows, roads and vegetation, etc.) models respectively from bottom to top. Fig.4b demonstrates the search functions about the building attribute information. The attributes and photographs of buildings related with the 3D models by codes, therefore users can achieve bi-direction data query. In addition, the transparency of each surface layer can be adjusted to show both underground and surface models at the same time.
4 CONCLUSIONS THE construction of three-dimensional virtual campus is a long and arduous systematic project. The paper studied the main technical processes and key technologies used in three-dimensional model of the campus and the process of system construction. Designed and implemented a three-dimensional virtual campus of Shandong Jianzhu University and achieved satisfactory test effect. However cause technical conditions and restrictions of raw data, the present work remains to be further improved. To develop and improve the three-dimensional virtual campus system further following work is also needed: (1) Improve the sophistication of the campus’ three-dimensional model and achieve the building interior three-dimensional inquiry function and the roaming function; (2) Integrate with the existing digital campus’ information technology functions so that lots of campus services and management functions can be ported to the three-dimensional virtual environment.
ACKNOWLEDGMENT The research work was supported by Shandong Province Natural Science Foundation under Grant No. ZR2011EEQ006.
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[10] [10]Lide Liu, Yashuang Zhang. Analysis and Application of digital the modelling methods of three-dimensional campus landscape Science and Technology Innovation Herald, 2011, 2(5):73-74. [11] Ward, Geoffrey C., and Ken Burns. The War: An Intimate History, 1941-1945. New York: Knopf, 2011
AUTHORS 1
Hao Liu (1991-) female, han nationality,
master,
research
field:
Traffic
GIS
2
Zimin Zhang (1976-) male, han nationality, doctor, main
research field: Emergency simulation and digital city etc. Email:
technology and applications, Shandong
zhangzimin@gmail.com
Jianzhu University.
3
Email: liuhaoo@yeah.net
field: Economic Geography and digital city, Shandong Jianzhu
Ying Zhou (1977-) female, han nationality, master, research
University.
- 145 http://www.j-es.org