[Radiance-general] increase resolution: BAM! fall off the end of the universe

[Georg Mischler]

George Michaelson wrote:

> > It could also be that you made your surfaces too glossy. Most people
> > greatly overestimate the amount of gloss in their visual environment.
> > In reality, gloss levels for non-metallic surfaces are typically
> > way below 5% (rather around 1 - 2%).
>
> Thats confusing. face on, short distance you can see very high quality
> reflected images in tupak finished MDF for instance. Ok, 6 months later
> the grease stains and dust make that more diffuse, but it 'seems' shiney
> to me. Again, does the eye do a better job of ignoring that?

The relative amount of light reflected in a specular way is
independent of the "quality" of that specular reflection. Even if
it amounts for less than 1% of the total reflection, it may still
give you a clear mirror image, as the eye is capable of filtering
out a surprising amount of background noise as created by the
diffusely reflected light.

Remember that the human eye is a highly dynamic system, and not a
static camera. It doesn't snap still images, but scans the scene
by moving around, while usually also varying its own position to
a certain degree. If you're driving through the rain in your car,
then it's a good idea to keep your head moving a little from one
side to the other. This will cause you to see that road sign
shifting behind different raindrops on the windscreen, and helps
the image processing unit in your head to seperate the "real"
information from the visual noise caused by the wet glass. The
same thing happens if you try to discern a mirror image in an
imperfectly reflecting surface.


> > Note btw., that the surrounding surfaces will *not* see a perfect
> > mirror image, unless you use the "mirror" material for the tap,
> > which you shouldn't. If you use just a shiny metal, then the diffuse
> > calculation from other nearby surfaces will hit the tap at most once
> > or twice, which isn't enough for an exact reflection. Only surfaces
> > that are very close will again see more, simply because the tap fills
> > a significant part of their surrounding space.
>
> Perhaps I did something wrong in my design. I found setting a minor colour
> change on the metal of fixtures had a huge effect on the tones of the
> surfaces that I presumed were reflecting it.

Global illumination in action!

You might want to compare your results to a photograph instead of
what you perceive when looking at the scene directly. The human
eye will adapt to the prevailing light color in the scene, and
filter out any global tints that it doesn't consider important.
You're visual apparatus performs a permanent and automatic white
balance correction, which doesn't happen when you make a picture
of the same scene.

Isn't it interesting how we only realize the extremely refined
inner workings of our perception when we try to simulate it by
computer?


-schorsch

-- 
Georg Mischler  --  simulations developer  --  schorsch at schorsch.com
+schorsch.com+  --  lighting design tools  --  http://www.schorsch.com/