Warp <war### [at] tagpovrayorg> wrote:
> > With the head so close to the surface, it is blocking the indirect light from
> > almost all directions except sideways, so it gets significantly less light
>
>   Also directly under the ear? The ear is so small that it's not blocking
> almost anything, yet the shadow on the floor produced by the ear is very
> pronounced.

You're talking about the left ear (the one to our right side) I guess. To me it
looks like it blocks part of the bright light coming through the window (the
blue patch on the wall), and therefore creates a very strong contrast.

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"Bill Pragnell" <bil### [at] hotmailcom> wrote:
> I didn't notice in the original, but the blue square on the wall is supposed to
> be a window. Assuming the outside to be very bright, I would expect the shadow
> under the head. Warp is correct though; without this assumption, the shadow
> isn't right.
>
> This makes the colour of the outside completely wrong, of course - it would need
> to be hundreds of times brighter to be believable.

Depends on what is on the outside - if we're talking about a moonlit night, with
a several-hundred-kilowatts spotlight blazing into the room, then it's quite
fine I guess :)

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"nemesis" <nam### [at] gmailcom> wrote:
> http://img377.imageshack.us/img377/7061/lightcutstest4radioxv4.jpg

Yuck - this radiosity implementation sucks... I'd rather have POV's artifacts
than these :)

(Would make a nice effect for some "help, the aliens are out to abduct me!" type
of scene, with the alien ship's floodlights seeping even through solid walls at
the room's corners...)

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clipka escreveu:
> "nemesis" <nam### [at] gmailcom> wrote:
>> http://img377.imageshack.us/img377/7061/lightcutstest4radioxv4.jpg
> 
> Yuck - this radiosity implementation sucks... I'd rather have POV's artifacts
> than these :)

It's vertex painting.  In order to have good radiosity, you should 
subdivide all your meshes as much as you can to get good results.  Plus, 
I've done the imbecile approach of having a plane for the floor that 
stretches outside!  So, some of the outside vertex close to the walls 
get painted white and it shows inside. :P

OTOH, after the radiosity calculations, the scene is rendered incredibly 
fast, much more than pov's.  I'm still to get to grips with the right 
settings, though... or perhaps not:  this lightcuts implementation 
permits this kind of baking as well. :)

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Bill Pragnell <bil### [at] hotmailcom> wrote:
> I didn't notice in the original, but the blue square on the wall is supposed to
> be a window. Assuming the outside to be very bright, I would expect the shadow
> under the head. Warp is correct though; without this assumption, the shadow
> isn't right.

  It isn't right with that window. The light square on the floor is light
coming from the window. The light is not directly illuminating anything else.

  Besides, if the shadow was produced from light coming from the window,
it would be a lot more elongated to the left, and the lighting of the head
would be more pronounced.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> Bill Pragnell <bil### [at] hotmailcom> wrote:
> > I didn't notice in the original, but the blue square on the wall is supposed to
> > be a window. Assuming the outside to be very bright, I would expect the shadow
> > under the head. Warp is correct though; without this assumption, the shadow
> > isn't right.
>
>   It isn't right with that window. The light square on the floor is light
> coming from the window. The light is not directly illuminating anything else.
>
>   Besides, if the shadow was produced from light coming from the window,
> it would be a lot more elongated to the left, and the lighting of the head
> would be more pronounced.

Well, I was thinking it was the actual sky casting the shadow, with the bright
spot on the floor cast by a point(ish) source in the sky. But in any case,
nemesis assures us the sky doesn't cast light, so I guess that shadow's all
wrong as you originally said. Additionally, I think the darkening in the
corners is far too extreme.

Bill

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"clipka" <nomail@nomail> wrote:
> "Bill Pragnell" <bil### [at] hotmailcom> wrote:
> > I didn't notice in the original, but the blue square on the wall is supposed to
> > be a window. Assuming the outside to be very bright, I would expect the shadow
> > under the head. Warp is correct though; without this assumption, the shadow
> > isn't right.
> >
> > This makes the colour of the outside completely wrong, of course - it would need
> > to be hundreds of times brighter to be believable.
>
> Depends on what is on the outside - if we're talking about a moonlit night, with
> a several-hundred-kilowatts spotlight blazing into the room, then it's quite
> fine I guess :)

Yesyes, ok :)

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Bill Pragnell escreveu:
> Well, I was thinking it was the actual sky casting the shadow, with the bright
> spot on the floor cast by a point(ish) source in the sky. But in any case,
> nemesis assures us the sky doesn't cast light, so I guess that shadow's all
> wrong as you originally said. Additionally, I think the darkening in the
> corners is far too extreme.

Coming home I'll do a povray radiosity render with the same scene and 
another lightcuts render looking above to see what is causing the 
shadows... from the viewport during the radiosity calculation window, it 
can be seen quite a bright area in the ceiling.

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Bill Pragnell <bil### [at] hotmailcom> wrote:
> spot on the floor cast by a point(ish) source in the sky. But in any case,
> nemesis assures us the sky doesn't cast light, so I guess that shadow's all
> wrong as you originally said.

  I don't have a problem with the shadow per se, as the ceiling and upper
walls are illuminated by the bright spot on the floor, and the ceiling and
walls probably will cause a darkening underneath the head. What bothers me
is how well-defined the shadow is. It's almost sharp. If the shadow is
caused by a large ceiling and walls, the shadow under the head should be
*very* smooth (as the ceiling would effectively be a huge area light), so
smooth that it should be almost shapeless. Such as well-defined shadow can
only be produced by a relatively small area light, which in itself would
make the head be lighted more strongly from that direction.

-- 
                                                          - Warp

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nemesis nous illumina en ce 2008-12-15 12:17 -->
> clipka escreveu:
>> "nemesis" <nam### [at] gmailcom> wrote:
>>> http://img377.imageshack.us/img377/7061/lightcutstest4radioxv4.jpg
>>
>> Yuck - this radiosity implementation sucks... I'd rather have POV's 
>> artifacts
>> than these :)
> 
> It's vertex painting.  In order to have good radiosity, you should 
> subdivide all your meshes as much as you can to get good results.  Plus, 
> I've done the imbecile approach of having a plane for the floor that 
> stretches outside!  So, some of the outside vertex close to the walls 
> get painted white and it shows inside. :P
> 
> OTOH, after the radiosity calculations, the scene is rendered incredibly 
> fast, much more than pov's.  I'm still to get to grips with the right 
> settings, though... or perhaps not:  this lightcuts implementation 
> permits this kind of baking as well. :)

Make the wall thicker! Add some thickness outside near the base. If you still 
see that kind of artefacts, then the implementation is buggy

-- 
Alain
-------------------------------------------------
Unitarian: Shit that happens to one person is just as bad as shit that happens 
to another.

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