3D modelling buildings in VGI

i am studying about 3d VGI and i am going to find an interoperable method for collecting 3d building information.
my question is about Modeling and Design of a 3D Volunteered Geographic Information System With an Interoperable Description for Basic Components of the Building.

you know,3d information about buildings are collecting by users and insert to osm by attributes and tags and then 3d building models are made by extruding footprints.
do you think, could be any way for collecting 3d information for buildings in a different method?
any way like 3d drawing and creating building models by users in a VGI site, could be useful?
is it useful for 3d VGI to make it possible for users to draw 3d exterior building elements like walls, doors,windows,roof?