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ISBN: 978-972-8939-25-0 © 2010 IADIS4.2 PhotoMap: Using Google Maps APIFigure 7 portrays PhotoMap, a WDiM application, which shows high-resolution Google Maps and posts thegeotagged photographs on the map. Geotags are location metadata assigned to the photograph. Theyrepresent a set of latitude and longitude. Geotagging is supported on most cellular telephones and handy GPSsystems.Services showing geotagged images on the map are not novel: Google Maps and Flickr provide suchservices. We must emphasize distributed parallel rendering on web browsers on 16 Players. Each Playerdraws a different part of the high-resolution map, constituting part of the image of the composite large-scalemap.The PhotoMap system is portrayed in Figure 8. PhotoMap hosts geotagged photographs; one is shown inWDiM with a vicinity map of shooting location. A user can change the displayed photograph from the hostedphotographs using a Wii remote and scroll to a new location in which the next photograph is taken coincidentwith changing photographs. PhotoMap, in short, is a high-resolution digital photograph frame application.Registration of photographs to PhotoMap is to upload to Coordinator via FTP and e-mail.Visualization of earth science data, especially high-resolution satellite images, is a major part ofapplications of expensive existing tiled display wall. PhotoMaps shows WDiM, which consists of low-endconsumer machines and which is based only on web technologies, can apply to visualization for earth science.5. MIDDLEWARE FOR WDIM5.1 ComponentsIn this section, we describe middleware that draws a high-resolution web application with user interaction.The middleware components are depicted in Figure 9. The middleware consists of a distributed webapplicationrendering engine and some third-party JavaScript library components including Ext.Js andFREDDY (Yokoyama et. al. 2009). The TileCongifuration file includes the number of monitors, size of thedisplay, and other useful information. WrapperCommander and WrapperReceiver are simple wrapperprograms of PHP; they load TileConfiguration and call Commander and Receiver of a user-developed WDiMapplication. The WDiM application consists of Commander, which is executed on the Conductor (NintendoWii/Opera), and Receiver which is executed on the Players. In addition, RESTful Web Services and AjaxProxy are placed on Coordinator as necessary.Commander is an HTML file that includes JavaScript code for Conductor and draws GUI on the monitor,receives user interaction using Wii Remote and sends commands to Receiver on Players. Receivers hascommand handlers, which are defined by the application developer and which await commands fromCommander. When Receivers receive a command from Commander, the corresponding handler is calledwith arguments.We provide abstract classes of Commander and Receiver to application developer. To develop WDiMapplications, the developer writes the subclasses of both Commander and Receiver and extends the abstractclasses to define the application logic.Figure 9. WDiM middleware componentsFigure 10. Messaging Mechanism of WDiM156