【正文】 from above but also providing perspectively distorted views. Furthermore, 2d maps or orthophotos can be draped over digital terrain models providing textured views (cf. Singh 2020). The draft specification of the WTS considers only (raster) images for output media. It is currently not specified which input data types can be used, from which sources they may be obtained, and how the WTS should bine them in order to render the images. Although the WTS specification still has the status of an OGC discussion paper, a first implementation is already available in the framework of the Java based open source system Deegree (Deegree 2020). To bridge the gap between 3d visualization using OGC data services (and thick clients) and the portrayal service WTS (and thin clients) the SIG 3d of the GDI NRW is working on the specification of a new dedicated 3d portrayal service called Web 3D Service (W3DS). It is based on the proposal of the WTS and extends it by the explicit consideration of 3d features and the output of 3d display elements. The W3DS is capable of generating output both on the image and the display element level of the portrayal pipeline. This way, a medium client can fetch 3d display elements from different W3DS which then are merged and shown simultaneously. 11 The mandatory output data format of the W3DS is VRML97 (see VRML97 1997). GeoVRML and X3D may also be delivered as optional resp. future data formats (see Reddy et al. 2020). Above, numerous (and in many cases free) 3d browsers and web brower plugins for VRML97 are available. Furthermore, most mercially available GIS, 3d CAD and 3d visualization systems offer VRML export and import functionalities. These systems can be made interoperable on the visualization level, if specific W3DS adapters are implemented for them. Due to the fact, that most systems already contain VRML export functions the implementation of an adapter should only cause minimal effort. 4. PILOT 3D OF THE GDI NRW In order to demonstrate and evaluate the possibilities of interoperable 3d geovisualization described in the previous chapter, the socalled ”Pilot 3D“ has been started within the initiative GDI NRW. It realizes the concepts explained in chapter three specific application projects. These projects are focused especially on the marketing, tourism and business development sector,but the employed technology can be applied for aspects of planning, telematics and real estate business as well. In the first project 3d city models for the two cities Cologne and Leverkusen are built up. 3d visualizations will integrate 3d building models, football stadiums, the airport and innercity industrial buildings. The application scenario will provide possibilities for interactive route planning and online ticket services. With regard to the Football World Cup 2020, a 3d route planning system will be established connecting the event locations to special public and economic buildings. Starting points will be Cologne main station, the CologneBonn airport and the motorway A1. Target points might be the RheinEnergy stadium in Cologne and the BayArena stadium in Leverkusen. On the way between these event locations further buildings can be integrated and accessed can place their logos in the 3d model. Furthermore, a cooperation with the CologneBonn airport, the public transportations and the Deutsche Bahn AG is possible. The target points can be explored interactively, functions like . online ticket services showing the view from the booked place can be incorporated. Based on this project, a widearea 3d city model of Cologne will be implemented and used for planning purposes in the future. In the urban area of D252。ger and Kolbe 2020). 2. DEMANDS AND CHANCES FOR DISTRIBUTED 3D GEOVISUALIZATION In the feasibility study, Virtual Regions in the RhineRuhr area 2020”which has been carried out by CeGi GmbH until ”July 2020 on behalf of the state government of North RhineWestphalia,Germany, current and future application fields for interoperable 3d GIS and 3d visualization have been identified and rated. The investigations are based on numerous and prehensive interviews with experts ing from business, administration, anisations and research institutions focused on their role as a provider resp. user of 3d geoinformation. . Overall chances of distributed 3D data resources According to the results of the feasibility study, an interoperable system of distributed 3d data resources provides the following chances and advantages (CeGi 2020b): . Interoperability and patibility By ensuring interoperability of data formats and systems the users can access arbitrary 3d spatial data sources in a homogeneous way. It allows the application of the same analysis and visualization tools for different data sets. The retrieval of appropriate geoinformation is supported by a metadata information system, which currently is developed for NRW. Although there already exist numerous international standards of the OpenGIS Consortium for data access and visualization (OGC 2020),some technical issues like the realtime exploration of 3d scenes over the inter presently only can be realized by proprietary software applications. Therefore, the questions concerning the right balance between standardisation and proprietary systems as well as concerning the capability of 3d GIS functionalities and 3d visualization services (. static or dynamic visualisation) have to be discussed. In the medium term, only a mixture of 4 standardbased and proprietary solutions can be realized. However, each application of standardised services, formats and modeling improves the system’s overall patibility and the patibility of providers and possible users. . Multiple use and sustainability Interoperability and patibility offer multiple usage of geoinformation as well