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Digital Earth > TerravisionTM > User Guide > Tcl/Tk > File Menu The File MenuNew ViewerTerraVision can display multiple viewers at once, and through the Links Menu you can connect these together. When TerraVision first starts, it creates a single viewer instance. However, you can choose to create further viewers by selecting this option. You can choose between opening either a 2D constrained viewer, or a full 3D viewer. Close ViewerThis option will close the current viewer. If this is the last viewer you have open, then this option will operate the same as if you had selected Quit.Open Dataset > Open TerrainThis option lets you load a specific TerraVision style dataset from your local database of datasets. From here you can select a dataset from the database, manage the contents of the database, and refresh the contents of the database by recontacting the specified servers. The Open Terrain window looks like:
At the top of this dialog, there is a text widget with the filename of your dataset database. The dataset database contains all instances of all datasets that you have told TerraVision about. You can enter a new filename here and press RETURN in order to load a different database. If the filename does not exist, then you will be asked if you want to create it. To the right of the database text widget there is a button marked "Servers...". Clicking on this button will bring up the Database Servers dialog. The main window contains the dataset selection area. To the left side you will see a list of "GeoSets". A GeoSet is simply a region for which both DEM and imagery datasets are available. If you select one of the names in this list then you will see all of the locations for all of the DEM and Image instances. For example, in the above image we have selected the "Earth (Gtopo30)" GeoSet and we see that there is 1 instances of the DEM and Imagery for this set: available over http. If TerraVision also knew about a local disk version of this dataset, or other web server locations, then a list of these would be displayed here. Once you have selected the dataset you wish to browse, you can press "Open Dataset". After a brief delay while TerraVision features the base information for the dataset, you will see the terrain appear in the viewer. Open Dataset > Open ModelTerraVision lets you overlay 3D models over the terrain. These could be building models, or weather simulations, or textual labels. The GeoVRML file format is supported as a rich 3D file format with support for accurate georeferencing information. 
The set of all available models is stored in your dataset database and updated whenever you reread a TerraVision dataset server. You can select any of the models displayed in the list and select the location that you wish to load it from (the same model could exist on multiple servers and on your local disk). You can also query a GeoVRML file to find out more about it, such as any author or copyright information that has been specified, as well as scene graph details such as how many texture or hyperlink nodes it contains. Open Dataset > Open DotGeoSRI's DotGeo architecture provides a highly-scalable mechanism to locate massive amounts of georeferenced data anywhere on the Web. In order to use this infrastructure, you must first connect to a DotGeo schema file, which provides full details on the location and structure of the DotGeo hierarchy. Once connected, TerraVision will automatically query the DotGeo index as you fly around and will actively stream any relevant terrain and 3D models to your display (N.B. this feature only works in the 2D viewer at present). 
In the Open DotGeo dialog, you can select the location of your desired DotGeo schema - a default schema is specified for you from SRI's web server. You may also specify the location of a hierarchy database, an XML file which contains the full database of information that is to be searched. Specifying a hierarchy file is useful for performing live demonstrations using a small subset of all available data. For more information on DotGeo, see http://www.dotgeo.net/. Close Dataset > Close TerrainThe Close Terrain option will display a list of all currently opened terrain models and give you the option to unload any of these from memory. Once closed, the terrain model will be removed from your view of the world.Close Dataset > Close ModelThe Close Model option will display a list of all currently opened 3D GeoVRML models and give you the option to unload any of these from memory. Once closed, the model will be removed from your view of the world.Close Dataset > Close DotGeoThis option opens the same window as the Open DotGeo option, where both connect and disconnect buttons can be found. Use the Disconnect button to sever an existing connect to DotGeo and stop datasets being discovered automatically.PropertiesThis facility lets you find out various pieces of information about the datasets that TerraVision is currently connected to. This includes details such as the name of the dataset, its type (image or dem), the total pyramid size, the ground resolution in pixels and ground units (meters or degrees), the location of the dataset, etc.The image below shows an example of the Properties window with a number of datasets loaded, and showing details for the gtopo30 terrain model. 
In addition to information for each dataset, the Properties window can display an Aggregate Report. This tells the user how many datasets are currently loaded, and what the total size is of all these DEM and OI datasets. The Aggregate Report also lists the total number of pixels in all of the loaded OI datasets, and the total number of DEM postings from all of the loaded DEM datasets. QuitGood-bye TerraVision; hello shell prompt/desktop.
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