The attached patch adds a game option option to allow the ground map to influence aerospace altitude (defaults to "false"). The details are discussed in this forum thread: http://megamek.info/forums/index.php?topic=2196.0
In addition, it adds the following helpful features:
Map view mode showing altitude instead of elevation, with corresponding change to the isomeric display
An "Atmosphere" class (with corresponding interface), allowing for configuration of the atmosphere in future patches, as well as adding the potential for per-altitude band atmospheric conditions (taking over most responsibilities from the PlanetaryConditions class instances). The instances of this class are per-board, in case multiple boards need to be supported in the future.
Right now, the patch only applies altitude bands according to the official altitude heights. More customisation, as well as simplified IAtmosphere subclasses for space and low altitude maps, are in development.
Patch created against version 0.41.7 of MegaMek.
Adding a bunch of 80x80 tiles test boards featuring "natural" obstacles.