Hi, I'm new to POV-Ray, so I've studied some works of the more experienced
artists out there. Some scenes of their works are quite complex and therefore,
they render very slow.

Now, I wonder how the modelling of such a complex scene is done; How is it
possible to model a complex scene, if the rendering gets extremely slow? Since
it becomes impossible at a certain point to keep all the things in mind in a
complex scene, the rendering of that scene (or parts of it) is the only way to
check what's going on, isn't it?

As far as I understand, it doesn't make any sense to wait a whole day for
rendering, just to check if a small object sits in the right place - after
spending one week in advance to find the proper camera-position to see whats
going on with that object ...

So, what's the story here?

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On 30-9-2011 6:50, Tommy377 wrote:
> Hi, I'm new to POV-Ray, so I've studied some works of the more experienced
> artists out there. Some scenes of their works are quite complex and therefore,
> they render very slow.
>
> Now, I wonder how the modelling of such a complex scene is done; How is it
> possible to model a complex scene, if the rendering gets extremely slow? Since
> it becomes impossible at a certain point to keep all the things in mind in a
> complex scene, the rendering of that scene (or parts of it) is the only way to
> check what's going on, isn't it?
>
> As far as I understand, it doesn't make any sense to wait a whole day for
> rendering, just to check if a small object sits in the right place - after
> spending one week in advance to find the proper camera-position to see whats
> going on with that object ...
>
> So, what's the story here?

What most people do while building their scenes, is to test-render using 
simpler settings, like switching off area lights, switching off media, 
switching off photons, using simple textures instead of complex ones, 
replacing complex render-intensive objects by placeholders...

Once everything is in place according to one's intentions, then one 
gradually switch back to the more complex and ultimate scene.

Very straightforward in fact.

Thomas

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> Hi, I'm new to POV-Ray, so I've studied some works of the more experienced
> artists out there. Some scenes of their works are quite complex and therefore,
> they render very slow.
>
> Now, I wonder how the modelling of such a complex scene is done; How is it
> possible to model a complex scene, if the rendering gets extremely slow? Since
> it becomes impossible at a certain point to keep all the things in mind in a
> complex scene, the rendering of that scene (or parts of it) is the only way to
> check what's going on, isn't it?
>
> As far as I understand, it doesn't make any sense to wait a whole day for
> rendering, just to check if a small object sits in the right place - after
> spending one week in advance to find the proper camera-position to see whats
> going on with that object ...
>
> So, what's the story here?
>
>
>

Those slow rendering scenes are the final product.
During devlopment, the scene gets lots of symplifications:

Complexe, often layered, textures can be replaced by simple pigments.
Some transparent and reflective objects are made opaque and non-reflective.
No use of antialiasing, area light, focal blur, or radiosity.
General, croase, radiosity settings using only plain white or other 
solid pigments and temporary removal of transparent objects.
Temporary removal, by comenting out, of several objects while working in 
a specific area.
Using test scenes to create some complexe objects without anything else.
Use of simple place holders when setting medias.

All this can combine to change a few days final render into a few hours, 
or even minutes, test render.

Also, you can render only a small part of the visible scene. Using the 
windows version, you can sellect an arbitrary area of the preview window 
and render only that part.
It can also be set using command line parameters.

Then, there are the quality options that can be set with +qn where "n" 
is an integer in the 0~9 range.
+q0 remove all lights and only use full ambient illumination using only 
pigments.

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As Alain noted, use a test scene for working on complex objects.  A 
generic test scene template with some predefined cameras, lights, and so 
on is a handy thing to have around.  (I added such a scene to my Insert 
menu for that purpose.)

An include file of generic "test" textures can be also be useful. 
Shiny, bright colored plastic textures can help you see the fine details 
of complex objects while you're building them.

Keep the code for any really complex object in its own include file so 
that you can easily (1) include it in a generic test scene while you're 
working on it; (2) include it in your main scene or omit it, as 
required; and (3) re-use it in other scenes.

--Sherry Shaw

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> As Alain noted, use a test scene for working on complex objects. A
> generic test scene template with some predefined cameras, lights, and so
> on is a handy thing to have around. (I added such a scene to my Insert
> menu for that purpose.)
>
> An include file of generic "test" textures can be also be useful. Shiny,
> bright colored plastic textures can help you see the fine details of
> complex objects while you're building them.
>
> Keep the code for any really complex object in its own include file so
> that you can easily (1) include it in a generic test scene while you're
> working on it; (2) include it in your main scene or omit it, as
> required; and (3) re-use it in other scenes.
>
> --Sherry Shaw

Such include file should #declare your object.
This allow you to add several copy of that object in a scene using a 
single #include statement.

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Thomas de Groot wrote:

> What most people do while building their scenes, is to test-render using 
> simpler settings, like switching off area lights, switching off media, 
> switching off photons, using simple textures instead of complex ones, 
> replacing complex render-intensive objects by placeholders...

Also note that, in practice, a convenient way to do this is to use
the #if statement to distinguish between the simple and complex code
based on some flag(s) you set at the beginning of the file.

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Christian Froeschlin <chr### [at] chrfrde> wrote:
> Thomas de Groot wrote:
>
> > What most people do while building their scenes, is to test-render using
> > simpler settings, like switching off area lights, switching off media,
> > switching off photons, using simple textures instead of complex ones,
> > replacing complex render-intensive objects by placeholders...
>
> Also note that, in practice, a convenient way to do this is to use
> the #if statement to distinguish between the simple and complex code
> based on some flag(s) you set at the beginning of the file.

#ifndef is your friend.  For example:
____________________________________________________________________________

#ifndef (Debug_house) #declare Debug_house = 0; #end
#ifndef (Debug_lawn) #declare Debug_lawn = 0; #end
#ifndef (Debug_tree) #declare Debug_tree = 0; #end
....

#if (Debug_house = 0)
   #declare House = union
   {  box { -1, 1 translate y }
      box { -1, 1 rotate 45*x scale <1, sqrt(0.5), sqrt(0.5)> translate 2*y }
      scale <5.5, 2.5, 3.5>
      pigment { rgb 1 }
   }
#else
   #declare t_Glass = //something slow
   #declare t_Shingles = //something slow
   #declare t_Outdoor_siding = //something slow
   #declare t_Stucco_ceiling = //something slow
   #declare t_Hardwood_floor = //something slow
   #declare Window = //something complicated
   #declare Roof = //something complicated
   #declare Door = //something complicated
   #declare House = union { /* something really complicated */ }
#end
....
____________________________________________________________________________

Then you can set the parameters from the command line or from within a .ini
file.  To work on your trees, you might set:

-a +q4 declare=Debug_tree=1

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