It should be possible optimize complex object by using several unions to
make automatic bounding more accurate. I think that it maybe not useful to
combine some two finite objects to own union because bounding system takes
also some prosessing time. Question is, how many objects to put nested
union?

Even that automatic bounding create perfect bounding box it should be still
possible to optimize complex object rendering by splitting complex object
to several unions. How can I calculate how many unions to split complex
object?

Matti

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> Even that automatic bounding create perfect bounding box it should be
still
> possible to optimize complex object rendering by splitting complex object
> to several unions. How can I calculate how many unions to split complex
> object?


Don't bother. Internally, POV-Ray splits all of the unions, and then does
exactly what you're describing using its *own* algorithm, which produces a
much more efficient bounding box "tree" than you or I could by hand. Chances
are, by using "split_unions off", you'll only slow things down.

 - Slime
[ http://www.slimeland.com/ ]

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On Thu, 24 Apr 2003 16:29:08 EDT, "Matti Karnaattu" <nomail@nomail>
wrote:

>Even that automatic bounding create perfect bounding box it should be still
>possible to optimize complex object rendering by splitting complex object
>to several unions. How can I calculate how many unions to split complex
>object?

With complex CSG, try bounding differences, as well as intersections
with infinite objects (most often planes). Then specify -ur on the
command line.

You can build your own bounding tree but POV will do it better *if* it
has the bounding box info. So it's best to just bound the unboundable
and specify -ur (do not remove user bounds).


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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>Don't bother. Internally, POV-Ray splits all of the unions, and then does
>exactly what you're describing using its *own* algorithm, which produces a
>much more efficient bounding box "tree" than you or I could by hand.

Thanks. How about meshes? I'm now working with mesh generation macro which
greate large meshes. I think that POV-Ray sets every mesh own bounding box
so splitting meshes greates more bounding boxes and optimization is
possible. How can I greate optimal mesh groups?

Matti

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Matti Karnaattu <nomail@nomail> wrote:
> Thanks. How about meshes? I'm now working with mesh generation macro which
> greate large meshes. I think that POV-Ray sets every mesh own bounding box
> so splitting meshes greates more bounding boxes and optimization is
> possible. How can I greate optimal mesh groups?

  AFAIK splitting meshes into several mesh-objects will only result in
slower rendering.
  In theory the larger amount of triangles you put into one single mesh
object, the faster it will be to render (compared to putting the same
triangles into several mesh objects).

  That is, for example: If you have a tree object consisting of a hundred
thousand distinct triangles (ie. all leaves and branches are different
and unique in shape), putting all the triangles into a single mesh object
gives (at least theoretically) optimal rendering speed.

  Naturally if there's repetition (eg. a branch consisting of a thousand
triangles repeats 50 times in the tree) then for the sake of memory
consumption optimization it's better to make a mesh of this repeating
shape and then instantiate it several times (eg. as the branches of the
tree).

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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In article <web.3eae9989d2eb664bbef0bd7d0@news.povray.org>,
 "Matti Karnaattu" <nomail@nomail> wrote:

> Thanks. How about meshes? I'm now working with mesh generation macro which
> greate large meshes. I think that POV-Ray sets every mesh own bounding box
> so splitting meshes greates more bounding boxes and optimization is
> possible. How can I greate optimal mesh groups?

Meshes use their own bounding heirarchy. Splitting them up is unlikely 
to do more than interfere with this and slow things down.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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