[vos-d] semantics

[Karsten Otto]

The problem here is the clash of two different mindsets, computer  
graphics people versus knowledge engineering people. The first prefer  
scene graphs, which are well understood as Braden pointed out, and  
are good for rendering. The second prefer semantic descriptions of  
objects and their relationships, which is slightly less well  
understood. Striving for a mix of both bears the potential for  
disaster, or at least to bad compromises as you pointed out.

That said, I'm actually quite happy with the current VOS model. The  
flexible typing allows a vobject to be both a semantic and geometric  
entity. It can be a misc:Avatar with descriptive properties, and a  
a3dl:Cone heading a scene graph structure. There are even child  
vobjects which are useful to both aspects, e.g. a3dl:position &  
friends. So far, this approach has worked out nicely, right?

What I'd like to do is improve this model in a few places, from a  
semantics point of view. For example, an a3dl:bounds child specifying  
the rough size and shape of a 3D entity would be helpful. It could  
give non-visual clients a better understanding of a scene, without  
requiring them to understand the actual scene graph data in order to  
compute this information.

Another point is the relation between the sector and its contents. So  
far, the relations only specify generic membership, as a set of  
conceptually unsorted and arbitrarily chosen contextual names. This  
does not mean anything to anybody, neither from a semantic nor scene  
graph view. I'd like to see a more structured approach here, using  
proper "role" names instead. For example, "m:avatar" for user  
avatars, "m:scenery" for (static) background entities, and so on.  
This makes it much easier for a client to select child vobjects of  
interest for inspection and caching.

Regards,
Karsten Otto (kao)