Warp wrote:
>   It would be nice to see some rendertimes.

I have been simply amazed by these "new breed of" renderers which use
unbiased methods that make the image converge slowly to the correct
solution. Just look at these amazing images made with indigo Renderer:

http://www.indigorenderer.com/joomla/index.php?option=com_gallery2&Itemid=26

The rendering times usually vary from few hours to tens of hours. But it
all depends on quality (ie. noise) requirements. You get a preview very
quickly with a lot of noise.

I've been implementing my own path tracer and my impressions are:

I love the fact that you always get (almost) all the characteristics of
light taken into account. You don't have to figure whether radiosity,
caustics, indirect shadows, indirect refractions etc.etc. play
significant role or not. You don't have to tweak tens of parameters and
guessimate which parameters/values/features give you the effect that the
renderer should handle in the first place. And you don't have to guess
if the artifact you see is really an artifact (because wrong parameters
or whatever) or correct result.

I just implemented specular reflections.After doing those I noticed:
"Wow, I just accidentally implemented caustics and phong shading". The
same way you don't have to guess which kind of light source and which
parameters you must use to get the desired effect. Every lightsource can
be of any shape (not just 2d fake sources or physically impossible
points) and every point on the light source surface does indeed emit
light. No parameters, no features to enable, no shadow artifacts. It
Just Works (tm).

The whole purpose of raytracer is to give you an accurate image.
Otherwise you could use faster scanline renderers. Brute-force renderers
really accomplish this as can be seen from the images. IMO (and this is
just my opinion) you quite rarely see images of such quality made with
Pov - at least compared to the ones rendered with Indigo. (By "quality"
I mean lighting realism - not necessarily model quality etc). In many
cases this is not because POV wasn't capable of producing almost as good
images. The reason is that it is difficult and time consuming to
guess/try/tweak which features/parameters you have to enable/set to get
realistic results. Many images made by new users look worse than 3D
games that are 5 years old. Had they used brute-force, the results would
be a lot more photorealistic with little effort.

The rendering time is not a that big problem in still images -
animations are a different matter. Brute-force renderers are very easily
made multi-threaded (I know because I did it just 3 hours ago...) and
thus they scale very well with new multi core CPUs.

I waited 3 hours for a small refractive sphere to get drawn on my screen
back in the 90s. I can wait the same 3 hours now to get true global
illumination, caustics and other very important effects of light and I
can be 100% certain that the result is accurate.

I also hope these new methods are considered when rewriting/designing of
Pov4 begins.

This was not a rant against POV. But things go forward and methods that
were impossible to use 10-20 years ago are now very usable and superior
in many regards. And after 5 years they are even more usable.

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