[vos-d] parameterized views

[Ken Taylor]

Karsten Otto wrote:

> Hi folks!
>
>  From the top of my head, I'd say this idea of yours sounds cool, but
> is probably going too far. After all, the idea is to present a
> synchronized world for everybody to *share*, i.e. Gibson's
> "consensual hallucination".  If every user gets to see the world in
> an entirely different way, you will ultimately wind up in a situation
> where everybody can only work in its own private (view of the) world,
> and nobody understands anybody else anymore...
>
> [example of different users seeing different AOI sets]

Some sort of area-of-interest management is absolutely essential for shared
virtual worlds of significant size. Think of something like Second Life or
Active Worlds -- with a very large area and tens of thousands of objects,
without the server filtering objects according to their distance from each
user, it would have to send the state of the entire world to everybody! That
would be a big problem, so instead you are able to see all objects that are
100m (or whatever) away from you, and the server only sends you updates
about those objects. As long as the distance is set far enough, it shouldn't
create a big immersion problem between users.

>
> Regarding (a), I don't see how a generic server could possibly
> support all weird kinds of queries a client may want to formulate.
> For example, assume your are at x=0. If a parent object P is at
> x=-20, but a child object C is at *relative* x=+15, do you report C
> in the 10 units AOI query? It is only 5 units away from you... but
> then, what about P? If you leave that out, C does not make sense! You
> may easily wind up in a situation like the conversation above.

This is a problem in the realm of real-time computer graphics in general.
Say an object's center point is 100m away from me and my client decides not
to view it. That's fine, unless the object is a mountain 200m wide! Having a
parent object with a child object far away from it, as you describe, is a
simliar problem. I'm not sure there's a really good, general solution to
this problem, either. Even modern videogames exhibit some "popping" of
distant objects. The best thing to do would probably be to try to design the
world to minimize these kinds of objects that make the calculation of
what-objects-are-close-enough-to-me difficult.

>
> Bottom line: Let's not encourage divergent behaviour to a point where
> it gets schizophrenic, rather try to support a strong consensus.
>

If two avatars are near enough each other to interact, they totally should
see a consistent world. But being able to deliver a different view per
client can be usable for many areas -- network efficiency, scalability,
accessibility, internationalization, etc. Also, there may be reasons to
"instance" off a part of a world so a user, or group of users, effectively
gets a private version of that 3d space. Video games is one application, or
any web site with very high volume that doesn't want to have over-crowded
spaces.

Ken