[Bf-funboard] Rigid Non-destructive sub-division

Ton Roosendaal bf-funboard@blender.org
Mon, 8 Sep 2003 12:08:44 +0200


Hi,

The Blender radiosity 'tool' already does this adaptive subdivision,  
subdividing faces with high energy transitions (i.e. shadows) on the  
fly.
Most obviously the disadvantage is for animation, where the  
continuously changing geometry might give a disturbing result.

My intuition is to choose for a system where the user can easily define  
extra subdivision levels for the parts that need it. That also is quite  
easy to code... but leaves the work to the artist, not the programmer!  
<evil grin>

An adaptive subdivision system doesn't integrate that easy with the  
current renderer, main reason why I left it out for this first release.  
I thought of first releasing this simple integration, collecting the  
feedback and examples from artists that provide the material for the  
next stage. I really lack sophisticated testing examples here...

Ilac; yep, subdivision code itself is not a problem... it's more of  
defining how it integrates in the interface and toolset nicely. Also to  
enable dispacement mapping for example. This is what was covered by  
Madprof's proposal for Effects.

-Ton-


On Monday, Sep 8, 2003, at 05:51 Europe/Amsterdam, Matt Ebb wrote:

> I think a better solution would be to do an adaptive subdivision on  
> the mesh at
> the same time as the radiosity (in the render process). By just  
> subdividing the
> entire mesh, if you have a floor plane with a small object on it, to  
> get well
> defined shadows under your object, you'd need to subdivide the whole  
> plane very
> finely = loads and loads of vertices, which = long render times. It  
> would be
> good to use some sort of automatic detection, and just subdivide the  
> areas that
> need the extra detail. There are plenty of papers on the net about  
> this topic -
> many landscape generation programs use this kind of technique to  
> localise detail
> only in the areas that need it.
>
> Quoting ilac <ilac@maltanet.net>:
>
>> THE PROBLEM:
>> The new radiosity system does not currently subdivide the mesh but  
>> works with
>> the available mesh. This is not a problem with organic meshes which  
>> have
>> sub-surfaces - but for 'rigid', non organic shapes like buildings,  
>> furniture
>> etc the user has to sub-divide the mesh manually before rendering.  
>> This
>> increases polygon count unnessesarily and makes editing harder after.
>>
>> So a sub-surface system which leaves the mesh as-is would be great!
>> Especially with Goofsters new loop cut tool, it is possible to easily  
>> control
>> the density of such a subsurface to specific places, while only  
>> increasing
>> the face count of the non sub-surf mesh minimally!
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Ton Roosendaal  Blender Foundation ton@blender.org  
http://www.blender.org