RE: [Algorithms] Re: Portal VS BSP

[Ville M. <wi...@hy...>]

Neil,

I think we classified portal culling (both screen-space axis-aligned as
well as 3d) as an "occlusion culling specialization of the
(hierarchical) view frustum culling algorithm (for fixed, specialized
scenes)" in the original dPVS manual (at least we did in the subsequent
journal paper), the same way I regard back-face culling to be an
"occlusion culling algorithm for closed, watertight objects with limited
camera motion" (think a moment about the latter :)). 

Yeah.. whatever .. the terminology is not vary straightforward anymore.
The last good taxonomy on VSD was done by Grant and that's what, 10 years
ago? About time someone would update it.

I have really nothing important or interesting to add into this
conversation, but just wanted to mention that it always confuses the heck
out of me when someone starts talking about BSP visibility :)

cheers,
-wili

Ville Miettinen
Head of Visual Research
Hybrid Graphics, Ltd.
http://www.hybrid.fi

On Mon, 15 Dec 2003, Neil Stewart wrote:

> > Wait a minute... portals vs. PVS vs. dynamic visibility. When 
> > did they multiply? I believe there were only two of those. :) 
> > By dynamic visibility I ment using portals in runtime. I 
> > don't know of any useable zone-based system with runtime 
> > visibility where you don't use portals.
> > What exactly are we talking about here?
> 
> LOL. I thought I knew. ;)
> 
> By dynamic visibility I was talking about something like dPVS, hierarchical
> occlusion maps and so on, i.e. there is no scene preprocessing. This is what
> I thought you were doing. I would classify portals as a static visibility
> solution if they are calculated from a static scene (and not some
> component-based thing).
> 
> > What we were using was dynamic visibility based on portals 
> > and with occluders put in the whole soup. So you get occluder 
> > fusion at run time, with little extra costs. What you are 
> 
> Ah, so we were advocating the same kind of thing: portals with occluder
> fusion. Which I think is a pretty good idea. ;)
> 
> I was only talking about PVS because the original question was "portal vs
> BSP" (actually "portal vs PVS"). Sorry for any confusion.
> 
> - Neil.
> 
> 
> 
> 
> 
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