Overview
The purpose of the tridicon™ CityDiscoverer software is to allow you to rapidly construct an interactive 3D visualization of any part of the real world.
The general process of building a visualization using the tridicon™ CityDiscoverer tools is to import data files into CityBuilder, manipulate them in a content-specific manner, then export them into a series of runtime files. The runtime files are placed into the appropriate Data directory, then CityDiscoverer is used for a realtime visualization of the data.
See the CityBuilder and CityDiscoverer documentation for the step-by-step process of reading your data in, and visualizing it. This includes elevation, roads, trees, buildings and fences.
If you have imagery that you wish to drape, that does not matches your elevation in projection and extents, then you will need to crop and/or re-project it to match. The tridicon™ CityDiscoverer software does not have these features. Here are some possible approaches you can use:
- If you happen to have it, many high-end software packages such as ERDAS Imagine can do these steps.
- The inexpensive software Global Mapper is capable of loading any number of images, displaying them with any given projection, and extracting a rectangular area (cropping).
- If you are technically savvy, the cross-platform open-source package GDAL provides a command-line tool called 'gdal_translate' which can be configured to re-project and extract rectangular areas. The
-projwin
option is useful for this purpose.- Finally, if you only need to extract a rectangular area, it may be possible to use a conventional bitmap application like PhotoShop to crop to the area of interest. This requires some manual arithmetic to turn coordinates into pixel values.
If you want to import your own, custom 3D models, here are some details about how the software supports them.
One of the things which CityDiscoverer can do is to place one or more instances of a 3D object on a terrain surface. In order to do this, it requires two types of files: one to specify the location of the object, and the other to specify the object surface geometry. The first file is a VT Structure File (VTST), and is typically created in CityBuilder based on GIS data representing object center points or footprints in a geographic coordinate system. (The "Content Manager" applications can also generate these.) The object geometry file can be in any format recognized by the underlying OpenSceneGraph system and is typically generated in a 3D surface modeler or CAD system. Typical formats include:
- .3DS (the export format from Discrete's Studio Max application, also exported by AutoCAD)
- .LWO (Lightwave)
- .FLT (OpenFlight format - with import/export plugin available for Alias|Wavefront's Maya)
- .OSG (OpenSceneGraph format).
- .XML (CityGML, this format is georeferenced and imported directly via the menu command "tridicon").
There is now some support for VRML 1.0 and other formats, check the OpenSceneGraph website for a full current list, and limitations. The application CManager can be used to preview your models to see how they will appear in CityDiscoverer.
In order to understand the relationship between the two files (VTST and 3D model) it is helpful to view the structure file contents. The VT structure file is itself a type of XML file, and can be viewed in a text editor. It can contain references (by name) to instances of 3D models. (It is the same format used for parametric building property descriptions used by CityDiscoverer in generating buildings procedurally at load time, but that is not relevant here.) The two types of files are placed in separate locations for runtime use:
- VTST files should go in the BuildingData folder, which is underneath the Data folder
- 3D object files can be located anywhere on your machine but are normally placed in directly or in a sub-folder of the BuildingModels folder.
Once you have the VTST files in place, they should show up CityDiscoverer settings dialog in the "Buildings" popup menu. (You can only have one VTST file per terrain.)