Am 27.04.2006 um 14:35 schrieb Benjamin Mesing:
I don't really know A3DL, but could you provide a rational why X3D is
not suitable, or A3DL is the better solution?
As I understood VOS, it is not only intended for human users, but for
software agents as well. In this case, the issue is related to scene
semantics. Also, it is not limited to X3D alone, but to most scene
description languages. Consider a simple example: For our virtual
park, we want to design a simple tree.
In VOS, we create a new metatype park:tree, and provide an
implementation for everything you might want to do with a tree. We
place it in the park by giving it a a3dl:position child, and adding
it to the sector. We also give it an a3dl:model property and
associated a3dl:material that contains some visual representation.
In the scene language, we construct a small scene graph instead. We
place the tree in the park by linking the parks toplevel node to a
transform node. The latter has a vertex set child, a polygon child,
and a material child, which together create the visual
representation. We also may associate a mouse listener and some
script with this data structure (likely the transform node) for
interaction.
For the human user there is no difference between the two, because
the user has the cognitive ability to recognize color and shape of
the visual representation as being a tree.
For an agent, the scene graph is just that - a generic data
structure, containing lists of values. It has not cognitive ability
to interpret this data as being a tree. Also, it has no GUI client,
and thus cannot interact with the tree, unless it uses some nasty
hack to simulate mouse clicks. In contrast, the agent can recognize
the VOS tree by looking at metatypes, and can interact with it by
calling methods on its proxy.
Regards,
Karsten Otto
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