Environment database issues Good environment databases can be expensive(not true for the future) Environment databases are difficult to handle by non-expert personnel Environment databases are often not very accurate(precision of 0.5m for horizontal coordinates and 1 to 5 m for vertical coordinates) Major limitation for ray modelsEnvironment database issues • Good environment databases can be expensive (not true for the future) • Environment databases are difficult to handle by non-expert personnel • Environment databases are often not very accurate (precision of 0.5m for horizontal coordinates and 1 to 5 m for vertical coordinates)  Major limitation for ray models 7