Adaptive rendering large and complex spatial data has become an important research issue in a 3DGIS application. In order to transmit the data to the client efficiently,this paper proposes a node-layer data model to manage the 3D scene. Because the large spatial data and limited network bandwidth are the main bottlenecks of web-based 3DGIS,a client/server architecture including progressive transmission methods and multiresolution representations,together with the spatial index,are developed to improve the performance. All this makes the application quite scalable. Experimental results reveal that the application works appropriately.
In the application of 3D Geoscience Modeling,we often need to generate the volumetric representations of geological bodies from their surface representations.Linear octree,as an efficient and easily operated volumetric model,is widely used in 3D Geoscience Modeling.This paper proposes an algorithm for fast and dynamic generation of linear octrees of geological bodies from their surface models under hardware acceleration.The Z-buffers are used to determine the attributes of octants and voxels in a fast way,and a divide-and-conquer strategy is adopted.A stack structure is exploited to record the subdivision,which allows generating linear octrees dynamically.The algorithm avoids large-scale sorting process and bypasses the compression in linear octrees generation.Experimental results indicate its high efficiency in generating linear octrees for large-scale geologic bodies.
DENG HaoZHANG LiQiangMAO XianChengMA JingTaoKANG ZhiZhongPENG JunHuanRUI XiaoPingLIU Liu
Adaptive rendering of large urban building models has become an important research issue in three-dimensional(3D)geographic information system(GIS)applications.This study explores a way for rendering web-based 3D urban building models.A client-server hybrid rendering approach is presented for large 3D city models,stored on a remote server through a network.The approach combines an efficient multi-hierarchical building representation with a novel image-based method,3D image impostor generated on demand by a remote server.This approach allows transferring complex scenes progressively while keeping high visualization quality.We also evaluated the rendering and data transferring performance of the proposed approach.
Liqiang ZhangChunming HanLiang ZhangXiaokun ZhangJonathan Li
