Bo Wan

Seamless integration of SQL Server spatial data on GIS platform

Integration and sharing of multi-source heterogeneous spatial data has always been the obstacle of GIS application. SQL Server spatial is a new important data source, how to integrate it into GIS platform is a problem worth studying. This study uses spatial data middleware technology to realize the seamless integration of SQL Server spatial data in MapGIS K9 platform. In this research, the data exchange mapping model between MapGIS K9 and SQL Server spatial, which includes data organization mapping and geometric entity mapping, is designed at semantic level. By the realization of this mapping model, SQL Server spatial middleware avoids complex data conversion and the loss of information, finally realizes the seamless integration. At the same time, the middleware provides a unified interface, enabling client software to directly access and operate heterogeneous spatial data. In addition, this middleware uses procedure, cache mechanism and spatial index to optimize the performance of data access and operation, greatly improving the practicality of the middleware.

An automatic incremental updating solution for multi-scale spatial database

Since spatial data are widely available for many areas around the globe, they bring a great convenient to peoples lives. And spatial database is used to arrange, analyze and view spatial data. In order to maintain real-time data, the way of spatial database updating was transformed from overall updating into incremental updating. Incremental updating only updates the change data in the map. The technologies of this updating way become an advanced international academic topic in recent years. In this paper, a multi-method updating solution is presented based on MMS-IU updating model. It supports two update approaches in order to adapt to the needs of multi-scale data updating. Two approaches using completely different operational modalities to acquire new spatial data. The disconnect edit update approach is fit for large scale data, whereas full version update approach is fit for small scale data. Furthermore, the model is event-driven, that can improve the utilization of spatial database. The paper also proposed a set of technology routes about incremental updating, such as automatic matching, versions comparison and conflict detect. The routes are based on many technologies, such as valid rules, version management and geometric matching. An implemented prototype are partly completed based on MapGIS7.3, the spatial database model of it is orient-Entities spatial database.

An Intelligent Multilayered Middleware Model and Heterogeneous Spatial Data Fusion Application Study

The seamless integration and fusion of current multisource and heterogeneous spatial data in the open and distributed environments is still a crucial task and has strong application requirements. Nowadays, heterogeneous data resource in different region can be shared but cannot be used through a uniform way. This paper adopts a novel and converse cognize process on real world, and puts forward an intelligent multilayered middleware model (IMLMW) which has the characteristics of layered, symmetric and intelligent, therefore distributed heterogeneous spatial data can be seamlessly integrated and fusioned through data interoperability, spatial reference unified, spatial data process and semantic fusion middleware layers, bringing gappy logical world return back to seamless real word. Stratification of the model makes each fusion process more clear and independent; Symmetry of the model makes heterogeneous data streams that flow thorough always maintain consistent data model; Intelligence of the model makes middleware chain extensible and embedded in relevant to the ability of heterogeneous data source itself. According to the model, an seamless fusion framework and system has been developed and implemented, the application of heterogeneous spatial data integration in Land Use Investigation Institute of Guangxi province has achieved good results. IMLMW model has been verified and proved to be viable and practical.

Evaluating the Accessibility of Healthcare Facilities Using an Integrated Catchment Area Approach

Accessibility is a major method for evaluating the distribution of service facilities and identifying areas in shortage of service. Traditional accessibility methods, however, are largely model-based and do not consider the actual utilization of services, which may lead to results that are different from those obtained when people’s actual behaviors are taken into account. Based on taxi GPS trajectory data, this paper proposed a novel integrated catchment area (ICA) that integrates actual human travel behavior to evaluate the accessibility to healthcare facilities in Shenzhen, China, using the enhanced two-step floating catchment area (E2SFCA) method. This method is called the E2SFCA-ICA method. First, access probability is proposed to depict the probability of visiting a healthcare facility. Then, integrated access probability (IAP), which integrates model-based access probability (MAP) and data-based access probability (DAP), is presented. Under the constraint of IAP, ICA is generated and divided into distinct subzones. Finally, the ICA and subzones are incorporated into the E2SFCA method to evaluate the accessibility of the top-tier hospitals in Shenzhen, China. The results show that the ICA not only reduces the differences between model-based catchment areas and data-based catchment areas, but also distinguishes the core catchment area, stable catchment area, uncertain catchment area and remote catchment area of healthcare facilities. The study also found that the accessibility of Shenzhen’s top-tier hospitals obtained with traditional catchment areas tends to be overestimated and more unequally distributed in space when compared to the accessibility obtained with integrated catchment areas.

MMS-IU Model for Incremental Update of Spatial Database

The update quality of spatial database determines the data’s value. Combined with the characteristics of the spatial database updating, we studied incremental updates modeling of the spatial database and supported a multi-mode update model, which referred to as the MMS-IU. The model has two features: (1) it contains two different update ways to enhance the applicability of the model; (2) we combine time and events with the version management mechanism, which let the model becomes an event-based and object-oriented update model. The article elaborated the basic principle of an updated way supported by the MMS-IU model - that is based-edit update way. Aimed at the obtainment for changes information, incremental information fusion, concurrency control such key issues which existed in updating process, we proposed a reasonable solution.

The general seamless integration model of spatial data and its algorithms

This paper introduces the concept of the two-phase seamless integration model (2P-SIM), which is a general model to describe and solve the seamless integration problem of spatial data in the distributed heterogeneous environment. The first phase of this model deal with the classify progress; after this phase spatial data participate in seamless integration is split into respective groups, each group corresponding a computation unit in the second phase. The second phase of the model can be split into three correlative parts, to deal with the spatial geometry seamless integration, the spatial object attribute seamless integration, and the accuracy fusion principle respectively. In each part, there are some elements or factors to describe and define various aspects of the seamless integration requirements and process manner; each element can select one of some predefined algorithms from the model, these algorithms are also illustrated and discussed.

Seamless map-layer and its seamless rules on distributed heterogeneous spatial data

The new generation of distributed GIS makes the management of distributed heterogeneous spatial data goes on a seamless integrated way, various kinds of spatial data centers appear. However, these data centers only integrate distributed heterogeneous spatial data but have a far way to achieve seamless application. Considering various kinds of physical gaps, this paper proposed the concept of seamless map-layer and defined 10 rules of seamless treatment to clear a variety of gaps existing at the same time. These seamless rules include spatial frame of reference, boundary smooth rules, property rules, multi-scale rules, and metadata rules. Then seamless cleaning process has been elaborated. Finally, in the prototype system which we have developed, heterogeneous land use data have been successfully cleaned and built as a seamless map-layer. Test improves the correctness, effectiveness and feasibility of such a seamless method. On the truly seamless map-layer, advanced seamless spatial application can be carried out.

Rules and Scripts Based Dynamic Spatial Data Catalogue Technique Study and Its Application

Catalogue technology has been widely used in spatial information organization, management and retrieval; it also plays vital effect in geography information system in organizing distributed and various spatial data resources. However, recent ways to describe catalogue tree, such as xml or database tables, lead fixed structure which is difficult to change, reuse and extend when facing masses of real-time spatial data. The directory service (OpenGIS Catalogue Services) standard developed by OGC (OpenGIS Consortium) only defines the directory service interoperable interface specifications but lacks of organizations and technology to implement. Thus, it is indispensable to develop a new method to manage masses of spatial data in spatial data warehouse or spatial data center systems in a facile, flexible and real-time way. Through analyzing common methods of representing and building catalogue system, this paper presents the novel concept of dynamic spatial data catalogue (DSDC) based upon these traditional model. Firstly, DSDC builds up a highly abstracted catalogue model for general directory description. Then, combining with the requirements of GIS application system, it developed a dynamic spatial data catalogue technique and mechanism using rules and scripts to produce the dynamic effect of catalogue representation. It detailedly introduced the key approach of the implementation using XML as the define language of rule, and using python as the script language. In this way, the catalog system will meet the requirements of faster development, easier extension, heterogeneous spatial data resource integration and real time reaction in a flexible way. DSDC technology is also an approach to build or integrate with any GIS systems rapidly. This paper discusses some applications of DSDC in various appropriate occasions, illustrates the integration of DSDC with MapGIS data center platform, and gives the application of DSDC in specific GIS application development and building process. The DSDC technology has been implemented and used in managing national 1:50000 basic geographic database resource and weather spatial data of Wuhan dynamically. Experiments prove that dynamic spatial data catalogue using rules and scripts has obvious advantages and will have huge potential in GIS applications.

A circuitous shortest path algorithm labeled by previous-arc vector group in navigation GIS

Path planning, as the core module of navigation GIS, its efficiency and accuracy has a crucial impact on the navigation system. General shortest-path algorithm is based on the classic node label-setting algorithm, which does not consider the situation of including circuitous road sections. Therefore, sometimes it will neglect the closer circuitous path at hand but find the farther path or even failed to find any path in the real road network with complicated traffic restrictions. For the sake of finding more accurate path, this paper presents a circuitous shortest path algorithm labeled by previous-arc vector group. Firstly, we generate incremental network topological relationships according to two random positions travelers are interested in. Secondly, we construct a vector group including previous arc, and seek the way by labeling the previous-arc vector group. Finally, the shortest path in the sense of mathematics which may contain circuitous road sections can be acquired. An experimental work has been done with this algorithm using the map of Beijing, which showed that the algorithm not only well improved the accuracy of the shortest path result between the two random positions in the road network, but also kept the efficiency of the classic node labeled algorithm.