The mission of the Custom Scenery project is
- to enhance existing and develop new tools and methods for scenery creation for FlightGear with the major goal to allow automatic processing and integration with the standard FlightGear scenery,
- to search for, to integrate and make available new and existing sources of free geodata for use in scenery creation or enhancement,
- to disseminate information and documentation enabling a community as large as possible to make use of these results, and
- to facilitate the creation of enhanced and customized scenery for as many places as possible in the world scenery by the community and by the project members themselves.
The goals and challenges for enhanced scenery
The current standard FlightGear scenery is based mostly on the VMAP0 dataset, which has a number of issues regarding accuracy, completeness and correctness. This makes it difficult to perform visual navigation according to well-known landmarks within FlightGear.
Real-life visual navigation in the air is characterized by identification of landmarks and structures in the map and on the ground and the matching of both to determine the current position of the aircraft. For this the major features of the landscape must be visible and recognisable.
A displacement of a road by a few hundred meters - as is present in the current scenery in many places, even in larger cities - may not be relevant at first sight, as a determination of the own position in visual navigation is typically not possible that accurate anyway.
However, the position and form of a feature relative to other features has an important effect on whether the feature can be identified with a feature on the map or not.
Take the area around Friedrichshafen in South Germany as an example (Google Maps). In reality and in the map there is a large road parallel to a two-lane railroad running alongside the runway of Friedrichshafen airport (EDNY) in northeast-southwest direction east of the airport. Also, there is no freeway in the vicinity of Friedrichshafen.
In the VMAP0 data (map from mapserver.flightgear.org) the road can be seen east of the airport, however, with a curious intersection with a freeway crossing north of the airport in east-west direction. It may be that such a freeway had been in planning. In reality and therefore neither in the official aeronautical maps nor in the experience of pilots flying here there is no such freeway. Further the railway passes the airport on its western side instead of its eastern side.
In essence, the railway is merely displaced by a few hundred meters. In relation to other features in the landscape, the picture is totally different from what would be expected looking at a correct aeronautical map. The additional ghost-freeway only adds to the confusion.
Another issue of interesting in visual aeronautical navigation is the fact that the maps only contain a small fraction of what is actually visible on the ground. Part of the exercise in pilot training is not to mix up different but similar features on the ground with a single feature on the map. Scenery therefore must show more than what's on the map.
Finally in real life it is most often not the actual features visible on the map that pilots are following. Rather many features, such as railroad lines or roads, are often identified by the differing slope or vegetation around the actual feature. This may also lead to pilots seemingly following a railroad to the end that is marked in the map, while already having passed that end and still following the embankment and the gravel of the abandoned part of the tracks.
These are the major challenges in providing enhanced scenery suitable for visual navigation.