地理立体视频Web服务框架设计与接口开发

地理立体视频是对视频帧扩展了内外方位元素等地理空间参照的立体视频,支持基于位置的视频查询和影像量测,提供了地理空间表达的一种新形式。随着Web服务技术的广泛应用,地理立体视频Web服务将进一步拓展视频GIS应用。本文重点讨论了地理立体视频Web服务原理和系统设计。通过分析服务功能,设计了由数据层、服务层及表现层构成的地理立体视频Web服务框架;利用REST风格的Web服务技术,从资源确定、URI定义,以及资源操作接口、表述格式等方面进行了服务设计,详细定义了检索服务、视频播放服务,以及影像量测服务接口及其HTTP交互机制,以WCF框架和ArcGIS Server平台实现了相应的服务接口。本文以河南大学金明校区为例,开发了地理立体视频Web服务原型系统并进行了应用实验。结果表明,地理立体视频Web服务实现了可视化、检索及量测等功能,适合于Web环境下视频GIS应用开发,对新型可定位多媒体Web服务的标准化具有参考价值。

Geographic Stereo Video Web Services: Framework Design and Interface Development

The traditional multimedia map, which combines map and multimedia elements, represents the geographic world more visually. With the rapid advance of the multimedia and position technology, the new-style geo-tagged media, such as geographic video, panoramic picture and measurable image, have been introduced in GIS applications. This paper aims to introduce the stereo video to GIS. Geographic stereo video includes both spatial and temporal geographic characteristics acquired through ground-based or non-ground-based cameras. It is the stereo video that extends the elements of interior and exterior orientation for video frame. Therefore, it supports the video retrieval and image measurement based on the spatial information, And it has been a new way for geographic representation. With the wide application of web service technology, geographic stereo video web service will further expand the video GIS application. To fully utilize the geographic stereo video resource in web environment, this paper aims to design a framework of geographic stereo video web services and to develop the related RESTful web interfaces. Based on the discussion of functional requirements such as visualization, querying and measurement, a web service framework composed of data layer, service layer and presentation layer for geographic stereo videos is introduced. All functions are packaged as a service in this framework and its communication are based on a unified interface, standard protocol and universal data format. The video URI resources, its representation format and related operation interfaces are defined carefully as the RESTful web services. The client-server interaction mechanisms for video querying, video displaying and image measurement are outlined in details. All the geographic stereo video web services are implemented on the basis of Windows Communication Foundation (WCF) and ArcGIS Server technologies. Based on the geographic stereo video service and browser-side AJAX (Asynchronous JavaScript and XML) programming, a prototype system of geographic stereo video web service for Henan University (Jinming campus) was developed. The prototype application shows that the service framework and system design introduced in this paper is feasible and adequate for video GIS application development. It is of reference value for web service standardization of new-style geo-tagged media.