Gong Jianya

Current issues in high-resolution earth observation technology

This paper reviewed the developments of the last ten years in the field of international high-resolution earth observation, and introduced the developmental status and plans for China’s high-resolution earth observation program. In addition, this paper expounded the transformation mechanism and procedure from earth observation data to geospatial information and geographical knowledge, and examined the key scientific and technological issues, including earth observation networks, high-precision image positioning, image understanding, automatic spatial information extraction, and focus services. These analyses provide a new impetus for pushing the application of China’s high-resolution earth observation system from a “quantity” to “quality” change, from China to the world, from providing products to providing online service.

AN INTEGRATED DATA MODEL IN THREE DIMENSIONAL GIS

The current GIS can only deal with 2-D or 2.5-D information on the earth surface. A new 3-D data structure and data model need to be designed for the 3-D GIS. This paper analyzes diverse 3-D spatial phenomena from mine to geology and their complicated relations, and proposes several new kinds of spatial objects including cross-section, column body and digital surface model to represent some special spatial phenomena like tunnels and irregular surfaces of an ore body. An integrated data structure including vector, raster and object-oriented data models is used to represent various 3-D spatial objects and their relations. The integrated data structure and object-oriented data model can be used as bases to design and realize a 3-D geographic information system.

A DESIGN OF THREE-DIMENSIONAL SPATIAL DATA MODEL AND ITS DATA STRUCTURE IN GEOLOGICAL EXPLORATION ENGINEERING

The key to develop 3-D GISs is the study on 3-D data model and data structure. Some of the data models and data structures have been presented by scholars. Because of the complexity of 3-D spatial phenomenon, there are no perfect data structures that can describe all spatial entities. Every data structure has its own advantages and disadvantages. It is difficult to design a single data structure to meet different needs. The important subject in the 3-D data models is developing a data model that has integrated vector and raster data structures. A special 3-D spatial data model based on distributing features of spatial entities should be designed. We took the geological exploration engineering as the research background and designed an integrated data model whose data structures integrats vector and raster data by adopting object-oriented technique. Research achievements are presented in this paper.

Design and Implementation of an Internet GIS

The development of Internet provides convenient environment for information searching and browsing. It also offers a new platform for geographic information processing and analysis. This paper discusses organization and processing approach to Internet geographic information, and provides a new method to cross-platform and distributed geographic information and its software implementation. The example is used to show the practicality and superiority of this method.

Research on Soil Moisture Sensor Nodes and Their Placement in Distributed Sensor Networks

In this paper two key factors of distributed sensor network for soil moisture monitoring are studied. One factor is the sensor design based on global navigation satellite system reflection (GNSS-R) signal, the other is the sensor placement. At first this paper introduces the construction and the advantage of non-contact soil moisture sensor, then the paper gives the optimization method based on greedy algorithm for sensor placement to conserving energy. Simulation results for multiple nodes placement confirm the validity of the proposed method.

Evaluation on the accuracy of digital elevation models

There is a growing interest in investigating the accuracy of digital elevation model (DEM). However people usually have an unbalanced view on DEM errors. They emphasize DEM sampling errors, but ignore the impact of DEM resolution and terrian roughness on the accuracy of terrain representation. This research puts forward the concept of DEM terrain representation error (Et) and then investigates the generation, factors, measurement and simulation of DEM terrain representation errors. A multi-resolution and multi-relief comparative approach is used as the major methodology in this research. The experiment reveals a quantitative relationship between the error and the variation of resolution and terrain roughness at a global level. Root mean square error (RMS Et) is regressed against surface profile curvature (V) and DEM resolution (R) at 10 resolution levels. It is found that the RMS Et may be expressed asRMS Et=(0.0061·V+0.0052)·V+0.2415. This result may be very useful in forecasting DEM accuracy, as well as in determining the DEM resolution related to the accuracy requirement of particular application.

GIS integration and interoperability based on GIS service chain

with the constantly enrichment of GIS Web Services, the most challenge we are facing now is how to dynamic combine those existing GIS Web Services to implement more complex tasks, thus to achieve the need of on-demand distributed geospatial information integration. This paper studies the key technology of distributed GIS Service Chain. First the paper proposes distributed GIS service chain integration architecture. Based on this integration architecture, key issues of GIS service chain integration are thoroughly studied. A prototype is implemented at the end of the paper. Keywords-GIS Service Chain; Distributed GIS Integration and Interoperability; Dynamic service choicing; visual Service composition

Implementation of OGC web map service based on web service

OGC Web Map Service is one kind of OGC Portrayal Services belongs to OGC Web Service model and it provides multi-platform interoperability of spatial data set. This paper presents a method for implementing OGC Web Map Service based on Web Service technique and introduces the detailed process.

A New Star Identification Algorithm based on Matching Probability

A new star identification algorithm based on matching probability is proposed for satellite attitude determination. In this algorithm, the brightest observed star is considered as the primary star, and the radial geometry pattern is constructed by linking the primary star to the other adjacent stars in the FOV. When a link is matched with star database, the two corresponding stars in the star database are recorded. The star with the most appearance times is regarded as the correspondence of the primary star. Experiments show that the computation time and the storage requirement of the algorithm are small, and the identification rate is high, compared with improved triangle matching algorithms.

Virtual globe-based integration and sharing service method of GeoSpatial Information

How to integrate and disseminate globally distributed multi-source and heterogeneous spatial information is an open problem in integration and sharing service of geographic information. Here we propose a new service architecture suitable for integration and sharing of distributed multi-source geographic information. We also propose a global virtual pyramid model, which can be applied in 3D virtual globes. In view of the difficulty of web multi-node geographic information sharing service, we propose a web multi-node service aggregation method, integrated in our autonomously developed virtual globe platform Geo-Globe and introduced in the National Platform for Common GeoSpatial Information Services named “TIANDITU”. It achieves 2D and 3D integration for geographic information service.