Tim Attwood wrote:
>> Could you try also with radiosity? Now your test image lacks global
>> illumination which contributes a lot to realism. Also the shadows seem
>> to be way too sharp considering the size of the emitting ball.
> 
> Here's one with a little bit better radiosity... high quality settings
> take a lot of time, these are medium settings. (26m)

Better but still there is something that is missing. I don't know. Maybe
it is the small color bleeding/caustics that make images either look
realistic or not. I attached a higher quality render of similar scene.
Noise is better and when scaled down it looks very smooth.

Of course my scene has spheres with more reflection and less diffuse
light overall. My scene has darker shadows. Your blue and white balls
have very different diffuse characteristics. Etc. Not really comparing
just apples. If I have time, I try to install POV to my Linux side and
try myself to replicate this scene.

Actually the whole thing of what constitutes a realistic looking image
is quite fascinating. There are definitely many things that are hard to
pin-point but which still makes use realize we are looking at GC image.
For my eyes it looks like brute force renderers (or any renderer that
shoots MANY rays and let them bounce) cover many of those things.

>> I also noticed caustics that can be seen below the green refractive
>> sphere. They came from reflections from the big yellow sphere. I guess
>> in POV you have to tell POV where to shoot photons? So you might also
>> miss these kind of effects?
> 
> Depends on what you mean by miss... you have control in POV to
> omit them if you want to. It's a different way of doing it.

Sadly it is more often the opposite, IMO. Images lack many features that
really should be there. We see images with no global illumination, no
caustics, no realistic shadows based on light source shape etc. So many
times I have seen an image which looks kinda "POVish". And then I see
something stunning which more than often meant that it was made with
another renderer. Again, I'm not necessarily saying that it can't be
done with POV, but it seems to be very difficult because you have to
enable and tweak all imaginable effects separately and use many "hacks".

> It's easy to miss the artifacts in any good image... for example where
> your red and yellow spheres have a bit of hall-of-mirrors the color
> fading into the distance is uneven, which is caused by the unbiased
> methods, but would eventually resolve. Or the sharp edges on the
> highlights seems a bit harsh, sort of like unintentional lens flares...
> another artifact that your mind subconsciously ignores. 

I don't know what you mean by uneven fading. Is it still present in this
higher quality render attached? The sharp highlights are result of the
way the image is generated. I consider anything above 1.0 pure white. So
if I have a VERY bright lightsource, then the "perfectly antialiased"
value is still way above 1.0 and we see rough edges. As you can see,
some spheres have smooth highlight and some rough. At this point this is
intentional but might change.

Post a reply to this message

Attachments:
Download 'kuva9.jpg' (76 KB)

Preview of image 'kuva9.jpg'