Warp wrote:

> Am I incorrect if I get the impression that these unbiased renderers
> offer nothing else than unbiased rendering? 

"Nothing else than perfect simulation of light". Nope, nothing else ;-)

> In other words, even the simplest of scenes will take hours to look
> ungrainy, no matter what you do?

Define "ungrainy". But yes, it is a tradeoff. You get grain, but you get
the same results no matter what features there are in the scene.
Caustics don't cost extra. Global illumination doesn't cost extra. Etc.
I can make a similar question:

With PovRay you don't see even one single renderd line with "perfect
radiosity/photon mapping/area light size, anti aliasing etc. It is a
trade-off, again.

Also, there are many ways to speed up brute force renderes. And there
are many ways to do it. Like path tracing, bidirectional path tracing
etc. You can implement various methods that reduces the amount of rays
needed for certain variance. I have yet to research those more.

>   Sometimes I use POV-Ray to get simple 3D-looking graphics for diverse
> things. The big advantage is that I can do it easily and POV-Ray renders
> it very fast. We are talking about a few seconds even for large-sized
> images. It would be completely counter-productive to have to wait for
> hours for a simple image to look non-grainy, when all you want is something
> quick which looks "cool" and "3D'ish".

I do the same thing now with my own program. I get a grainy preview
pretty quickly. And the grainy preview show perfect features. If you
simply want "3D-looking graphics" there are many a lot faster and better
options than PovRay. You discard the realism but you get it fast. I'm
more interested in photorealism.

>   For this reason even if POV-Ray in the future supports unbiased rendering,
> it should always be an *alternative* method of rendering, not the only
> available one. Removing the current phongshading-based rendering would be
> a setback in many areas. After all, POV-Ray is not *always* used for
> physical simulations of reality.

I agree that there are situations where you need speed over accuracy.
That is true. But also the opposite is true. After all, POV was created
to create realistic images - not the give decent results as fast as
possible. I'm not sure what is the general opinion: do users want to get
the best possible results in longer time - or okayish results in less time?

I belong to the first group.

I attached a very simple scene that took 10minutes to render to this
noise level. You can see caustics where reflective sphere and ground
meets. This is a simple scene where POV would be a lot faster (if you
know how to set it up properly..) Im also sure that good brute force
renderers give a lot better results in shorter time than my immature
renderer. The second image was done in 50 seconds. Just to show the
difference.

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