Yongning Wen

Topological relationships calculation for 3D curves data set based on monotone chains

Topological relations are research focus in 3D GIS. Constructing nodes and arcs from curves, building the topological relations of these primitives with their parent geometry and other geometries, and forming the topological graph, are the basis of the calculation of topological relationship. The formal description and smallest set of topological relationships of 3D curves are given. The line segments intersection algorithm computational geometry and the traditional line segments intersection algorithm in GIS are discussed, and a new algorithm based on the monotone chains are proposed to building the topological graph. The method of curves splitting and intersection algorithm of curves are analyzed. Topological graph is constructed based on the label of the topological primitives. Then, a comparison between the monotone chains method and the tradition algorithm is listed. Some experiments are carried out to testify the algorithm performance.

GIS-based family tree system integration

With the advancement of electronization and digitization of family tree, information sharing and function integration have become the bottleneck of the development and application of family tree. To address the problems such as the existing family tree systems are mutually closed and incompatible, family tree information representation is incomplete and non-standard, time and space information implied in family tree information is not well excavated and expressed, family tree information is repeatedly collected by each system, this paper proposes to parse and position family tree information under the Consistently Spatial-temporal Framework by using GIS technique, in order to regularize the expression and sharing of family tree information. Absorbing the VGI idea, people are encouraged to collaboratively collect and share family tree information. This paper discusses some key issues about the integration of family tree systems from aspects of the Consistently Spatial-temporal Framework, information sharing, interoperability, application mode etc. It designs a prototype of integration framework of family tree systems based on GIS and implements it by taking HXJP-GIS system and DZP-PGV system as an example. The practice indicates that the framework is feasible. It provides some new conceptions, reference methods and technical supports to construct the Chinese Family Tree Database and Platform for better protecting and utilizing family tree.

GIS-based family tree information sharing and service

To address the issues of family tree information sharing, mining and spatial-temporal analyzing, this paper introduces database, network and GIS technologies into the research of family tree. It studies the mode of family tree standardization, digitization, spatialization and networking, and discusses the theory foundation, implementing techniques, cooperation platform of family tree information sharing based on GIS. Firstly, according to the elements and characteristics of Chinese family tree by learning bibliographic and content of genealogy, this paper develops a description specification of Chinese family tree information. Then, based on consistently spatial-temporal framework, a family tree spatial-temporal data model cored with person and event is designed, and the system of family tree geographic information service is established. Finally, it proposes to construct a website group of the Family Tree GIS integrating surname website, clan website and personal blog, in order to gradually build a community-based, open, multi-level platform for family tree information sharing and serving which serves for both general public and experts.

Knowledge-based geographic model integration

To quickly respond to development of the information technology, GIS must be able to create, manage and optimize spatial analyses. Building up spatial analyses using pre-existing geographic models can lead to higher efficiency in fulfilling complex analytical goal. We propose a knowledge-based approach, which meets spatial analyses requirements by integrating distributed and heterogeneous geographic model sources spread over the web. This paper suggests that geographic model integration should be based on the knowledge that we can separate it into syntactic wrapping, semantic representation and domain mapping sub-problems. The architecture for knowledge-based geographic model integration is presented that comprises several functional layers to provide web services to locate, share, and publish model sources. This paper will emphasize on knowledge-based approach to support geographic model integration to simplify the cooperation of geographic scientists.

A 3D topology model for multiple topological representations based on combinatorial maps

The formal representation of topological relations plays a very important role in process of spatial query, spatial analysis and spatial reasoning. Most current models support a single representation of geometry and topology at a fixed resolution. While it often happens that different applications take into consideration spatial data/topological relationship, with the same 3D scene date, under different viewpoints, in different geometric forms and/or with different resolutions. In this case, a topology model for multiple topological representations is needed. In this paper, we propose a new approach based on combinatorial maps, which focus on both multiple topological representations under the situation of LOD and Feature semantic/spatial aggregation and the consistency of topology.

A Study of Geographic Problem Solving Environment in Cooperative Distributed Design

To adapt well to modern distributed and heterogeneous network environment, geographic information systems (GIS) should be able to create, manage and optimize spatial analyses. Building up spatial analyses using pre-existing spatial data and geographic models, which are from different regions and belong to different institutes, can lead to higher efficiency in solving complex geographic problems. Cooperative distributed geographic problem solving environment (CDGPSE) offers an interactive, efficient, and feasible environment through which geographically separated geographers can conduct collaborative work. In this paper, resources layer, service layer, integration layer and application layer are tightly coupled to develop a CDGPSE system. Using Web Services-based architecture is efficient to integrate and share distributed resources as well as modelling procedures built on different platforms. Finally, a prototype system is implemented for collaboration on geographic problem solving on the groundwater. The experimental results show that the architecture developed in this paper is efficient and feasible.

Study on data mining technology in hyperspectral remote sensing

In this paper, the problems rise in hyperspectral data mining and some key issues should pay attention to were proposed based on the analysis on the state-of-art of hyperspectral data mining. The problems are as follows: data mining precision, mining algorithm efficiency, new hyperspectral data mining algorithms, the uncertainty in hyperspectral data mining, visualization in hyperspectral data mining process, and knowledge presentation, interpretation, estimation and management etc.. Some key issues should emphasize in the future are: systematic hyperspectral data mining theory, dimensionality reduction, mining spatial and temporal knowledge from images, and mining distributed data and mining multi-agent data. Also the framework and architecture of hyperspectral data mining were put forward in this paper. Hyperspectral data mining framework includes some subparts as follows: data selection, data preprocessing, data transfer, data mining and pattern estimation. And the architecture is composed of database, data warehouse, database management system, repository, mining process, user interface etc.. At last, an algorithm which named Relational perspective map (RPM) was introduced into the field of hyperspectral data mining. By the experiment on the spectra data from USGS spectral library, it proves that this algorithm is suitable to discover those spectral features and to identify and discriminate object classes based on their spectra.

A hybrid 3D spatial data structure for the integration of aboveground, ground and underground objects

A hybrid 3D spatial data structure for the integration of aboveground, ground and underground objects based on spatial cognition theory is proposed, which considers the space subdivision and topology completeness. Object-oriented method is used to abstract objects in real world which is defined into three levels. Geometry primitives and topology primitives are defined in this data structure. Topology is the option of the geometry. The geometry information can be coded in a binary method to store in the relation database. An experiment is designed to integrate the buildings, terrain, and geological stratification seamlessly. The data structure could express aboveground, ground and underground objects effectively.

Research on constructing 3D scenelite model based on 2D structure drawings of buildings

3D building model is the important foundation of constructing virtual landscape of 3D city. This paper will focus on building models and construct buildings in small scene with existing survey data based on the secondary development of Google SketchUp. The concept of scenelite will be illustrated. The research shows that the method can effectively reduce the redundancy of repeated work in modeling. It is useful for querying, managing the building objects, and performing 3D topological analysis with the scenelite model.

Distributed Geographical Model Service Based on WSRF

Numerous geographical models distributed in different geographical locations or cyberspaces lead to difficulties for sophisticated geographical problems solving due to the heterogeneity and decentralization. Grid computer technology provides a new way to solve problems in geographical sharing and service based on geospatial information technology. The method for understanding, describing and representing geographical models and geographical model service based on WSRF are discussed in this paper, and distributed geographical model sharing service framework is proposed. A prototype of distributed heterogeneous geographical models service platform is developed, and some experiments are implemented to examine the proposed methods. The proposed platform can provide a geographical resource sharing environment for geographical problem solving and geographical experimental in cyberspace.