Poser hand & Wings3D candle (inspired by a detail from the 1642 oil painting
"Saint Joseph charpentier" by Georges de la Tour), rendered with an
experimental version of POV-Ray 3.7

ca. 8 min. on a 64-bit QuadCore (AMD Phenom X4 9640 2.3 GHz, 6.0 GB RAM)

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Preview of image 'handsandcandle.png'

That is very good indeed!

However (there always is a however it seems) what is missing now is the 
shadow as it were of the finger bones. The fingers now seem empty wax 
containers. You could try with the Poser skeleton maybe. I am not sure, as I 
have never used it, but it should be complete and accurate.

Thomas

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"Thomas de Groot" <tDOTdegroot@interDOTnlANOTHERDOTnet> wrote:
> However (there always is a however it seems) what is missing now is the
> shadow as it were of the finger bones. The fingers now seem empty wax
> containers. You could try with the Poser skeleton maybe. I am not sure, as I
> have never used it, but it should be complete and accurate.

That, unfortunately, is a thing I expect to remain difficult with this lighting
model, as it does not do a full volumetric simulation.

Depending on the optimizations that will ultimately wind up in the code, adding
bones would have either a too strong effect, or none at all.

(Attached another shot in which we can see the candle a bit better)

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Preview of image 'handsandcandle.png'

"clipka" <nomail@nomail> wrote:
> (Attached another shot in which we can see the candle a bit better)


Where's that tiny green highlight on the left coming from?

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"sooperFoX" <bon### [at] gmailcom> wrote:
> "clipka" <nomail@nomail> wrote:
> > (Attached another shot in which we can see the candle a bit better)
>
> Where's that tiny green highlight on the left coming from?

Why - that's an artifact of course ;)

The hand mesh is quite wrinkled right there, and the algorithm probably still
contains a few loopholes. Nothing I'm too worried about at the moment - other
ToDo's have precedence.

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"clipka" <nomail@nomail> wrote:
> Poser hand & Wings3D candle (inspired by a detail from the 1642 oil painting
> "Saint Joseph charpentier" by Georges de la Tour), rendered with an
> experimental version of POV-Ray 3.7

Of course there could always be improvements, but this looks very good.  It
would be a very welcome addition to POV-Ray.  Did you ever figure out the
problem with discrepancies in the intensity?  Either way, thanks for your
continued effort!

 - Ricky

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"clipka" <nomail@nomail> wrote:
> Poser hand & Wings3D candle (inspired by a detail from the 1642 oil painting
> "Saint Joseph charpentier" by Georges de la Tour), rendered with an
> experimental version of POV-Ray 3.7
>
> ca. 8 min. on a 64-bit QuadCore (AMD Phenom X4 9640 2.3 GHz, 6.0 GB RAM)

The waxy look without volumetrics is to be expected, but the performance is
worth it.

Is it texture dependent?  In Blender, one can overcome the waxy look somewhat by
layering a few textures with different SSS settings.

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"triple_r" <nomail@nomail> wrote:
> Did you ever figure out the problem with discrepancies in the intensity?

You mean the issues I mentioned recently, with that crazy factor I found
necessary? Those are solved. I found out I had a major misconception about how
to integrate the incoming light intensity; instead of adding up the sample
values (scaled reciprocal to sample density), I basically just computed a
weighted average. With the far-off regions having much lower density and
therefore higher weight, but contributing virtually nothing but blackness, this
of course was *far* too dark >_<.

The results are still too dark for some yet unexplained reason, but since a
constant factor of 2.00 seems a perfect match regardless of choice of sample
points, scene scale, material parameters and what-have-you, I'm confident
enough that the output is right, so I'll just postpone that to later.

Instead, I'm now a bit worried about the single-scattering term; I'd have
expected it to contribute more to the overall brightness, but I don't have any
reference. I don't trust Tariq & Ibarria's results (and besides it seems that
they just vanished from the 'net these days), and the original paper by Jensen
et al. does not specify the values used for their "marble" bust shots showing
the individual components, which they custom-tailored to get an approximately
1:1 contribution of both terms.

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"nemesis" <nam### [at] gmailcom> wrote:
> The waxy look without volumetrics is to be expected, but the performance is
> worth it.

The best thing about current performance is that the code hasn't even been
examined for possible optimizations yet.


> Is it texture dependent?  In Blender, one can overcome the waxy look somewhat by
> layering a few textures with different SSS settings.

Hey, give me a chance - I've only just started on this! :P

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Thomas de Groot nous illumina en ce 2009-03-22 04:06 -->
> That is very good indeed!
> 
> However (there always is a however it seems) what is missing now is the 
> shadow as it were of the finger bones. The fingers now seem empty wax 
> containers. You could try with the Poser skeleton maybe. I am not sure, as I 
> have never used it, but it should be complete and accurate.
> 
> Thomas
> 
> 
Acording to my own experience, when light diffuse trough the hand's skin like 
that, you have a hard time noticing the bones at all, maybe a prety slight 
darkening in the middle, but that's all.

So, for the hand, ignoring the bones seems to be an acurate compromise.

-- 
Alain
-------------------------------------------------
Islam: If shit happens, kill the person responsible.

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