NVG 1.4 and 1.5 define several types of shapes. Most of them are quite common, such as polygons or ellipses, and some are more specific, such as corridors. NVG 2.0 defines additional properties, such as a time span, and additional shapes such as orbit and rectangle. In addition, the area shapes in the NVG 2.0 model are special in that they can contain inner rings (holes). Hence, the TLcdNVG20Polygon class implements LuciadLightspeed’s ILcdSurface interface, rather than ILcdPolygon. All other shapes directly implement the corresponding LuciadLightspeed interfaces, such as ILcdPolygon, ILcdEllipse, and so on.

Figure 1. Principal classes of the NVG 1.4/1.5 domain model

You can semantically link all objects extending TLcdNVG15MapObject or TLcdNVG20SymbolizedContent to a symbol from a symbology, such as the military symbology MIL-STD 2525c. Create the link by setting their TLcdNVGSymbol property.

Figure 2. Principal classes of the NVG 2.0 domain model

NVG documents allow per-object styling. Domain objects extending TLcdNVG15Base or TLcdNVG20Content expose a TLcdNVGStyle property detailing the styling information. TLcdNVGStyle 's styling properties can be null, which specifies that a default value should be used. The Customizing the NVG visualization guide further explains this process.