Zhengwei Sui

Visualization methods of vector data on a Digital Earth System

With the rapid development of Digital Earth System, vector data has been widely used as an important data model. Visualization methods to vector data on a Digital Earth System have got more attention. So far, the existing methods can be divided into geometry-based and texture-based approaches basically, and each kind of method applies to different areas with serious shortages in practice. For instance, the texture-based approaches require high memory and the accuracy of the vector data which is unpleasant when zoom in, while the geometry-based approaches have to increase the number of geometric primitives in order to avoid rendering artifacts. To remedy these deficiencies, M. Schneider, M. Guthe and R. klein proposed a texture-based method in 2005 which creates textures on-the-fly and a perspective reparameterization which is applied taking into account the current point-of-view, and then they presented a geometry-based method in 2007 which is based on the stencil shadow volume algorithm. Both of these methods have been greatly improved compared to the previous methods. In this paper, we analyse these two methods and compare their advantages and disadvantages, then conclude with a discussion of their suitable range in practice and give ideas for future improvement.

On the use of cloud computing for geospatial workflow applications

The Cloud is considered to be an important platform for the execution of scientific applications such as scientific workflows. Effective plan and management are desired in complex spatial analysis and decision applications. Geospatial workflow provides a scientific solution to manage such geospatial processes; it can define geospatial processes precisely to solve particular spatial-referenced issues in GIS applications. In this paper we explore the use of cloud computing for geospatial workflow applications, focusing on a well-known geospatial application - Weights of Evidence Method Metallogenic Prediction. We propose the architecture of geospatial workflow applications in the Cloud as well as across Clouds, elaborate each of the components of the framework, including how the application could be deployed in a cloud environment, along with structure changes, useful tools and services. Finally we discuss the challenges of deploying and executing geospatial workflows in cloud environment and whether the widely used scientific workflow management system is able to support Sky computing by executing a single geospatial workflow across multiple Cloud infrastructures at the same time.

Research and application on 2D and 3D interactively automatic construction technology of 3D model

How to use the 3D (three-dimensional) modeling techniques better is the core problem in Digital City, which is also a harsh topic during the development of 3D GIS. Key problems in current 3D modeling techniques used in 3D GIS applications are discussed in this paper, and 2D and 3D interactively automatic construction technology of 3D model is presented. It constructs 3D model by extracting the region of the building from the high resolution remote sensing images. Integrating ArcGIS 2D GIS platform and ChinaStar 3D GIS platform, it combines 2D and 3D interactive model adjusting tools and rich libraries of model textures, and can implement automatic construction of 3D model conveniently and efficiently with higher match accuracy between the 3D model and the high resolution remote sensing images and lower technical requirements to the modelers, It provides a feasible plan of the high simulated 3D models automatic construction to achieve Digital City.

A framework for distributed metadata management of mineral information resources with access control

Distributed metadata management is an efficient way to address the huge data of mineral information resources, which are usually distributed stored. In this paper, existing related metadata standards of mineral resource are firstly explored, based on which three typical kinds of metadata management mode, centralized metadata management mode, distributed metadata management mode and shared metadata management mode are summarized and evaluated. Considering the advantages and disadvantages of the three modes and the features of management, a framework for distributed metadata management of mineral information resources with access control is proposed to provide data management and share ability with access control. In this framework, a mineral information metadata table based on the standard published by China Geological Survey is defined to describe the metadata of distributed mineral information resources. The framework provides metadata and catalogue management abilities to fulfill data share and access control between different departments. The detailed design of the management framework is also given in this paper.

A non-recursive algorithm based on the quad-tree when required data missing

This paper mainly focuses on non-recursive algorithm on the base of the quad-tree for the situation that some data is missing during real-time visualization of massive multiplex dataset. This study introduces different kinds of basic data structures, including wait-static, wait-queue, main-static, missing-static and missing-queue. Upper level of the missing data can be found because of controllability of non-recursive algorithm and coordination between stacks and queues. The result of experiments shows that non-recursive algorithm is more efficient than recursive algorithm in solving the problem of data missing.

Exploration on application models of three-dimensional architectural models used in the Digital City

In the extension process of the Digital City, there are many geographic information application platforms using three-dimensional architectural models, but the aim is only to create three-dimensional view effects. The abundant data of models is not fully used. The purpose of this paper is to make a preliminary exploration on application models of the three-dimensional architectural model used in the digital city, putting forward an application model for the use of three-dimensional architectural models and other multimedia data in the Digital City.