nemesis <nam### [at] nospamgmailcom> wrote:
> Well, it does seem to handle indeed a huge amount of point lights
> automatically generated from quite a few light sources.  But it seems
> about as slow as any other GI method.  OTOH, there doesn't seem to be
> any radiosity count limit.  And, I wonder if it'd be more amenable to
> multiprocessing than radiosity...

I'd guess so. With radiosity, lots of interim results would have to be shared
beteen adjacent pixels. With Lightcuts, theoretically you'd have just the one
light source tree that would be shared, and for each pixel you would calculate
a new cut of the tree anyway, so no need for sharing this information (although
it *could* be shared among pixels calculated in the same thread, in order to
speed up finding the optimal cut. If there is any sense in doing so.)

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nemesis <nam### [at] nospamgmailcom> wrote:
> http://img440.imageshack.us/img440/1255/lightcutstestzg0.jpg

  The shadow under the head doesn't make physical sense. Where is it
coming from? That shadow would indicate that there's a strong light
source above the head, but the illumination of the head does not correspond
to this. The bright area on the floor would rather obviously not cause
such a shadow.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> nemesis <nam### [at] nospamgmailcom> wrote:
> > http://img440.imageshack.us/img440/1255/lightcutstestzg0.jpg
>
>   The shadow under the head doesn't make physical sense. Where is it
> coming from? That shadow would indicate that there's a strong light
> source above the head, but the illumination of the head does not correspond
> to this. The bright area on the floor would rather obviously not cause
> such a shadow.

I've put 3 bounces or more.  Probably some of the light in the bright area on
the floor under direct illumination bounce to the ceiling, then down again.  It
is present in the radiosity version too, though much less sharp:

http://img111.imageshack.us/img111/7218/lightcutstest3radiobm0.jpg

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Warp <war### [at] tagpovrayorg> wrote:
> nemesis <nam### [at] nospamgmailcom> wrote:
> > http://img440.imageshack.us/img440/1255/lightcutstestzg0.jpg
>
>   The shadow under the head doesn't make physical sense. Where is it
> coming from? That shadow would indicate that there's a strong light
> source above the head, but the illumination of the head does not correspond
> to this. The bright area on the floor would rather obviously not cause
> such a shadow.

You're forgetting about all the indirect scattered light.

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
(plus, light of same intensity from sideways is actually weaker at illuminating
a surface).

The indirect lighting in this picture seems quite exaggerated to me, but apart
from that there's nothing wrong with this.

Radiosity will produce a shadow there as well. Or at least it should - if it
doesn't it's off reality.

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clipka <nomail@nomail> 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.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> clipka <nomail@nomail> 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.

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.

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"Bill Pragnell" <bil### [at] hotmailcom> wrote:
> This makes the colour of the outside completely wrong, of course - it would need
> to be hundreds of times brighter to be believable.

Yes, sorry.  Blender's default background is that color.  I just didn't change
it and it looks dark outside.  It has no influence on the lighting, though.

I did provide a link to the radiosity version where I also took the time to
change the background to some more sunny-day look-alike. :)

Yes, the shadows are very sharp and pronounced and I'm not quite sure wether
it's because there's too much brightness, the Blender implementation is still
buggy or whatnot.  Don't you guys think it's funny though when we begin
wondering wether a synthetic image is correct or our own assumptions about how
it should work in real life? ;)

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Two more radiosity renderings.  Thankfully, after some half-hour of
pre-calculating, taking shots from other angles is a breeze.

http://img377.imageshack.us/img377/7061/lightcutstest4radioxv4.jpg
http://img377.imageshack.us/img377/3884/lightcutstest4radio2dh3.jpg

I increased the mesh resolution of the ground, so the shadow of the ear is more
visible, though still faint.  I'd guess it has to do with the fact that sharp
shadows are not really possible with radiosity.

Also, while not seen in none of these scenes, there's quite a bright spot in the
ceiling, no doubt contributing for the shadow below.  It is itself illuminated
by some of the ground outside (I put the floor as a plane rather than part of
the cubic room).

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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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