3D geospatial data for the web


To face the challenges of volume, access speed, diversity of devices, and the need for interoperability, the OGC and the Web3D consortium held a joint ‘Web3D geospatial portrayal’ workshop at this year’s Web3D conference in San Sebastian, Spain. While the Web3D community is focusing on open standards for real-time 3D visualisation including streaming, the OGC is developing a server-side 3D portrayal service interface to build interoperable access to 3D geodata servers. The aim of such a service interface is to support server-side and client-side rendering of huge datasets, as well as to enable different levels of user interaction, including visual exploration and querying further information on features from the server. â©
3DPIEâ©

Based on the results of the 3DPIE, the 3D portrayal standards working group (3D portrayal SWG) was founded. This group is chartered to progress the W3DS and WVS proposals to the point where they become one integrated, adopted OGC standard. This 3D portrayal service will provide a major building block for distributed spatial data infrastructures. Various types of applications would benefit from implementing an open service interface that enables them to present, explore and analyse complex 3D geodata from diverse sources. Applications built on this open standard would complement geospatial workflows and create new ways of using geo-spatial information and processes. â©

The OGC 3D portrayal standard will support both client- and server-side rendering. The client-side rendering approach is similar to the former OGC W3DS draft specification. The client requests a 3D model from the server. The server extracts the requested model from the 3D geodata server and generates a 3D scene graph including geometry and textures. Depending on the server’s capabilities, data formats such as X3D, KML and COLLADA will be used to store the scene graph. The rendering of the scene graph will be done on the client side. To build a W3DS client in a web browser, X3DOM and/or XML3D can be used to integrate the scene into HTML5. In principle, the scene graph can be transferred using other technologies such as JSON. â©

The advantage of combining client-side and server-side rendering into one standard interface is that it is open for upcoming mixed approaches as well. For instance, foreground objects might be transferred as a 3D scene graph, while objects that are further away will be rendered on the server. This might be a useful approach in augmented reality scenarios. â©

It is planned to publish the 3D portrayal service document for public comments at the end of this year. The specification will be hosted on GitHub, so that it is easy to follow the latest changes and to see the rationales of the 3D portrayal SWG members improving it bit by bit. â©

Applications built on this open standard would complement geospatial workflows and create new ways of using geo-spatial information and processesâ©

Volker Coors is a professor at Hochschule für Technik, Stuttgart, Germany, and a member of the OGC’s 3D portrayal standards working group. More information

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