Xplo Eristotle wrote:
> 
> My intent was to make this an early morning scene. Unfortunately, while
> the sky works well for this, the lighting itself seems strongly
> reminiscent of late afternoon! (At least, to me and a lot of other
> people who've seen it.) I have no idea how to fix this; quick tests in
> Photoshop to add brighter/dimmer/cooler light only made the lighting
> look strange. I suppose I should be happy that the lighting is
> convincing enough to suggest *any* particular time of day, but I would
> be happier with the one that I was aiming for. ;)

I think the clouds look good, but a bit too red.  Some media could be good
for morning atmosphere too.

> A couple notes on radiosity settings: first, the only light_source is a
> "sun" placed well outside the room, and the count for this image was
> only 100. I achieved this level of smoothness with a high error_bound
> and a low low_error_factor (1 and .1, respectively). More testing is
> needed to determine if this method can replace typical low error_bound
> radiosity settings in other situations, unless someone's already done
> some and I missed it, but I'll let someone with a faster computer than
> mine do that testing!

Hmm, it looks really quite accurate for error_bound 1, but i am not sure
if it's a very good method. What recursion_limit did you use? Have you
tried varying pretrace_end?

> Second, judging from the color bleed on the floor,
> it appears that radiosity "bounces" off of reflective surfaces; is this
> true? 

Yes, somehow. Reflection is calculated for radiosity samples.

> Third, you can see the back of the room is full of artifacts; I
> don't know if this is because of poor lighting, or because the radiosity
> data in the reflected image is only a crude approximation.

I'm not sure, but such a scene seems a quite difficult setup for radiosity
in general.  How does it look with more conventional radiosity settings?

> I'll probably keep working on this; it would make a pretty cool scene
> with window glass, blinds, pictures on the walls, maybe a ceiling fan,
> and gods know what (a table, maybe?) in the middle, even if most of it
> would only be visible in the reflection. Okay, I'll shut up and let you
> see the pic now.. comments welcome as usual.
> 

It looks nice, my submission for the 10best cover image contest has a
similar configuration (but a bit different lighting) and i was forced to
use fairly low radiosity settings because it was that slow.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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"Xplo Eristotle" <inq### [at] unforgettablecom> wrote in message
news:3BFF76A6.F83284F6@unforgettable.com...
>
> My intent was to make this an early morning scene. Unfortunately, while
> the sky works well for this, the lighting itself seems strongly
> reminiscent of late afternoon! (At least, to me and a lot of other
> people who've seen it.) I have no idea how to fix this; quick tests in
> Photoshop to add brighter/dimmer/cooler light only made the lighting
> look strange. I suppose I should be happy that the lighting is
> convincing enough to suggest *any* particular time of day, but I would
> be happier with the one that I was aiming for. ;)

Yellower sunlight for morning, yellow-orange for late afternoon pre-evening.
That's my thinking on it.  And of course both can actually be quite
orange-red too if the sun is at horizon.  The colors of sunlight is a rather
important thing to consider.

> A couple notes on radiosity settings: first, the only light_source is a
> "sun" placed well outside the room, and the count for this image was
> only 100. I achieved this level of smoothness with a high error_bound
> and a low low_error_factor (1 and .1, respectively). More testing is
> needed to determine if this method can replace typical low error_bound
> radiosity settings in other situations, unless someone's already done
> some and I missed it, but I'll let someone with a faster computer than
> mine do that testing! Second, judging from the color bleed on the floor,
> it appears that radiosity "bounces" off of reflective surfaces; is this
> true? Third, you can see the back of the room is full of artifacts; I
> don't know if this is because of poor lighting, or because the radiosity
> data in the reflected image is only a crude approximation.

You're probably forgetting about using higher max_trace_level.  I've used
error_bound 1 before and thought it did well depending on the scene.
The back wall isn't what distracts me, it's the edges of wall and floor.

bob h

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"Bob H." <omn### [at] msncom> wrote in message
news:3bff9fc2$1@news.povray.org...
> Yellower sunlight for morning, yellow-orange for late afternoon
pre-evening.
> That's my thinking on it.

Actually I feel that the sunlight tends to be whiter/grayer in the morning
whilst the sun is very red.

Mick

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I also meant to say it is cooler in the mornings with less dust in the air.

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Christoph Hormann wrote:
> 
> Xplo Eristotle wrote:
> >
> > A couple notes on radiosity settings: first, the only light_source is a
> > "sun" placed well outside the room, and the count for this image was
> > only 100. I achieved this level of smoothness with a high error_bound
> > and a low low_error_factor (1 and .1, respectively). More testing is
> > needed to determine if this method can replace typical low error_bound
> > radiosity settings in other situations, unless someone's already done
> > some and I missed it, but I'll let someone with a faster computer than
> > mine do that testing!
> 
> Hmm, it looks really quite accurate for error_bound 1, but i am not sure
> if it's a very good method. What recursion_limit did you use? Have you
> tried varying pretrace_end?

recursion_limit 2, and no. As I said, my computer is slow, which
discourages extensive testing. I'll probably do some spot testing (maybe
in that top corner) later, but the current settings are good enough to
work with.

> I'm not sure, but such a scene seems a quite difficult setup for radiosity
> in general.  How does it look with more conventional radiosity settings?

Like any other room lit mostly by radiosity: lots of artifacts, even on
flat surfaces.

> It looks nice, my submission for the 10best cover image contest has a
> similar configuration (but a bit different lighting) and i was forced to
> use fairly low radiosity settings because it was that slow.

The radiosity is the only slow thing in my scene; without it, this image
would render in a couple of minutes, rather than several hours.

-Xplo

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"Bob H." wrote:
> 
> You're probably forgetting about using higher max_trace_level.  I've used
> error_bound 1 before and thought it did well depending on the scene.

What effect would that have? I only have one reflective object in the
scene. (Well, technically, three, but the other two aren't really
obvious.) AFAIK, max_trace_level has no direct effect on radiosity.

-Xplo

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It does have. Try setting it to 2 and you'll see (your recursion limit will
be lowered to 1).
Max_trace_level 1 disables radiosity at all...

--
Jonathan.
"Xplo Eristotle" <inq### [at] unforgettablecom> ha scritto nel messaggio
news:3C0014B8.D5F39AFE@unforgettable.com...
> "Bob H." wrote:
> >
> > You're probably forgetting about using higher max_trace_level.  I've
used
> > error_bound 1 before and thought it did well depending on the scene.
>
> What effect would that have? I only have one reflective object in the
> scene. (Well, technically, three, but the other two aren't really
> obvious.) AFAIK, max_trace_level has no direct effect on radiosity.
>
> -Xplo

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JRG wrote:
> 
> It does have. Try setting it to 2 and you'll see (your recursion limit will
> be lowered to 1).
> Max_trace_level 1 disables radiosity at all...

So, assuming I've left it at the default of 5, and have a
recursion_limit of 2, what effect would it have again to raise the max_trace_level?

-Xplo

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I wasn't referring particularly to your scene. But you can  be sure that a
max_trace_level of 5 in a radiosity scene with at least ONE reflecting
object isn't enough in most cases. I don't know why but it often causes
polka dots.
I would increase it to at least 10. It shouldn't be slower.

--
Jonathan.
"Xplo Eristotle" <inq### [at] unforgettablecom> ha scritto nel messaggio
news:3C005D7D.3F8D7C7A@unforgettable.com...
> JRG wrote:
> >
> > It does have. Try setting it to 2 and you'll see (your recursion limit
will
> > be lowered to 1).
> > Max_trace_level 1 disables radiosity at all...
>
> So, assuming I've left it at the default of 5, and have a
> recursion_limit of 2, what effect would it have again to raise the
max_trace_level?
>
> -Xplo

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JRG wrote:
> 
> I wasn't referring particularly to your scene. But you can  be sure that a
> max_trace_level of 5 in a radiosity scene with at least ONE reflecting
> object isn't enough in most cases. I don't know why but it often causes
> polka dots.
> I would increase it to at least 10. It shouldn't be slower.

To tell the truth, it's probably 20. (Almost) all of my scenes have that
set in the globals, unless I change it by hand.

-Xplo

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