The battle takes place in a Cornell type of box. These reveal how good a
renderer simulates reality. There is nothing fancy about textures here, but
you get to see soft shadows, caustics, specular reflection and refraction,
diffuse indirect illumination with color bleeding, and anti-aliasing.

The attached picture is a 3-pass rendering in MegaPOV1.0. The 3 passes
combined takes roughly 24 minutes on AMD 1.4 GHz.. My motivation is to
demonstrate modern POV-Ray. I found this page yesterday that I think is
quite interesting: http://www.winosi.onlinehome.de/

If you browse to the gallery, you'll see the same scene as mine, rendered
with different softwares. The homepage also demonstrates "WinOSi" that is an
interesting renderer. Very slow, but very realistic.

My scene is not pure global illumination such as WinOSi, but an attempt to
balance all the available variables. Anyway, we're not throwing the exact
same variables into all renderers and expect the optimal output. But I
haven't changed the scene in any major way.

Please let me know what you think.

Regards,
Hugo

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Attachments:
Download 'illum2-final.jpg' (24 KB)

Preview of image 'illum2-final.jpg'

"Hugo Asm" <hua### [at] post3teledk> wrote in news:3f509b18@news.povray.org:

> The battle takes place in a Cornell type of box. These reveal how good
> [...]

Nice Job!  Very nice indeed.  I think one of Povray and derivitives' 
strongest assets is also it's most challenging aspects: the incredible 
amount of parameters and options.  To get the best renders, you need to 
know what you are doing and experience goes a long way.

Strange thing I found about the site you linked was how sometimes the same 
scene was nicely rendered, but the light on the ceiling was heavily 
aliased?  What's up with that?

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> how sometimes the same scene was nicely rendered,
> but the light on the ceiling was heavily aliased?
> What's up with that?

Yes, it's bad anti aliasing. It's because, when the lit plate is acting as a
true light source, that illuminates the entire room, it has to be very
bright. Much brighter than what you can see on a computer monitor / TV. So
the brightness is clipped on screen, but not in the calculation. Their
anti-aliasing doesn't take this into account. In POV-Ray, this IS taken into
account... Unless you use focal blur (that, when activated it replaces AA).

Actually, in this case I didn't use the lit plate as true source of
illumination. It's too small for that, and would require much higher
radiosity settings. I remove this plate
completely during radiosity calculation (the second pass) to avoid signs of
splotcy patches.

..More info available upon request.

Regards,
Hugo

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Nice image, I think you reached your goal, it is really comparable to 
the WinOSi one. What do you mean by 'demonstrate the modern POVRay' ?

The approach of the WinOSi renderer seems interesting, but I understand 
why it is so slow, and I must remark that all the scenes are very basic 
scenes with few simple objects only. I look forward more powerfull 
computers to be able to use this kind of things, but I'd rather see them 
included in POVRay some day because one needs fast rendering methods as 
well when setting up a scene.

JC

Hugo Asm wrote:
> The battle takes place in a Cornell type of box. These reveal how good a
> renderer simulates reality. There is nothing fancy about textures here, but
> you get to see soft shadows, caustics, specular reflection and refraction,
> diffuse indirect illumination with color bleeding, and anti-aliasing.
> 
> The attached picture is a 3-pass rendering in MegaPOV1.0. The 3 passes
> combined takes roughly 24 minutes on AMD 1.4 GHz.. My motivation is to
> demonstrate modern POV-Ray. I found this page yesterday that I think is
> quite interesting: http://www.winosi.onlinehome.de/
> 
> If you browse to the gallery, you'll see the same scene as mine, rendered
> with different softwares. The homepage also demonstrates "WinOSi" that is an
> interesting renderer. Very slow, but very realistic.
> 
> My scene is not pure global illumination such as WinOSi, but an attempt to
> balance all the available variables. Anyway, we're not throwing the exact
> same variables into all renderers and expect the optimal output. But I
> haven't changed the scene in any major way.
> 
> Please let me know what you think.
> 
> Regards,
> Hugo
> 
> 
>

Post a reply to this message

> What do you mean by 'demonstrate the modern POVRay' ?

Oh, I just think the examples of POV-Ray renderings on the WinOSi homepage,
needs to be updated, because POV can do better today.. I've tried to proove
it.. If there's nothing else I can improve in this image (?) I'm going to
send it to the author of WinOSi.. Just in case he wants to update his
homepage.

> I'd rather see them included in POVRay some day
> because one needs fast rendering methods as
> well when setting up a scene.

I agree, and cooperation is more important than competition.

Greetings,
Hugo

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Hugo Asm wrote:
> Please let me know what you think.
Sweet, but try to put in the front wall with no_image, so it can be seen 
  in the reflections. You can use the same trick for the green wall as 
well, if you want to use the original camera position. Just do a normal 
save radiosity pass and then a load with no_image also for the green 
one. That's how I did a no-lights version of this scene last winter.
Too bad no_image means no_radiosity. It would be great to be able to 
hide stuff like walls in this case and they would still affect the lighting.

Trace on,
Ari-Matti

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> Just do a normal save radiosity pass and then a load
> with no_image

aaah! The solution to my problem! Of course. I'll do this!

> That's how I did a no-lights version of this scene last winter.

I can't find it...?

-Hugo-

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> aaah! The solution to my problem! Of course. I'll do this!

Actually, that doesn't work. Having these walls in the scene during
radiosity will hide everything behind them. When I use no_image in the final
pass, these areas becomes visible again but no radiosity was calculated for
them. The result looks bad. So I can only get the backwall into the
reflections, as you suggested, but it will not be included in radiosity. So
it's going to make things unreal.

Regards,
Hugo

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Hugo Asm wrote:

>>That's how I did a no-lights version of this scene last winter.
> 
> 
> I can't find it...?
Didn't post it. :) Actually haven't been here or poved that much since.. 
dunno.. at least year and I've totally lost the little touch I had. :(

How many photons are you using? I tried to add photons, but can't find a 
good spacing to get rid of the splotches.

A-M

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> How many photons are you using?

Very few. They are shot during render pass 1. All lights but one has been
removed from this pass, to speed up photon calculation there is only one,
strong light at the lit plate on the ceiling.

During pass 2 (radiosity calculation) there are a grid of 4*4 area_lights at
the ceiling, to fill the room with something that resembles the physical
dimension of the lit plate. All of these lights are weak but together they
generate as much light as pass 1. However this grid of weak lights would
generate splotchy photons (no matter what I do) not to mention slow down the
process. So photons are turned off here.

Pass 3 combines the precalculated photons and radiosity, with high quality
AA, and turns on most reflections including blurred reflections on the
floor.


> I tried to add photons, but can't find a
> good spacing to get rid of the splotches.

To be precise, it's:

photons {
   spacing 0.01
   autostop 0
}

And the scene geometry is small. The overall bounding box is circa 4*4
units.

Regards,
Hugo

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