Severi Salminen wrote:
> Mike Raiford wrote:
> 
>> You didn't answer his question. I'm also curious about render times, but
>> you completely dodged the question.
> 
> See the indigo site gallery. Some captions include render time. Of
> course that tells you nothing about how good/bad the image looked in
> less time. Remember that with brute force you see a lot even after 1 minute.

How long do you have to wait before the graininess has reliably become 
unnoticeable?  That's a question I need an answer to before I can use 
any unbiased renderer for animation work.  I need a renderer that won't 
give me a picture unless the quality is consistent from one frame to the 
next.

With scanline and ray-tracing renderers, there comes a specific point at 
which the renderer is *done* with the image and is ready to render the 
next image.  Unbiased renderers are never really done; they just go 
until the user decides the quality is good enough.  Sure, the user may 
be able to set the renderer to go only a certain amount of time, but 
except for a very short clip, and only after rendering a couple of 
frames in that clip, can the time required for each frame be predicted 
with any meaningful reliability.

Regards,
John

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> With scanline and ray-tracing renderers, there comes a specific point at 
> which the renderer is *done* with the image and is ready to render the 
> next image.  Unbiased renderers are never really done; they just go 
> until the user decides the quality is good enough.  Sure, the user may 
> be able to set the renderer to go only a certain amount of time, but 
> except for a very short clip, and only after rendering a couple of 
> frames in that clip, can the time required for each frame be predicted 
> with any meaningful reliability.

On the only unbiased renderer I used, it uses passes. Being *based* on 
random numbers (shooting rays in random directions), of course the time 
each pass takes is non-deterministic, but you surely could render the 
same number of passes for all frames (instead of leaving it the same 
amount of time), and you would get approximately the same amount of 
noise on all.

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Nekar wrote:
> Do scientist completely understand all the
> properties of light?

Pretty much, yes. :-)

-- 
   Darren New / San Diego, CA, USA (PST)
     On what day did God create the body thetans?

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news: 47bc9dbf$1@news.povray.org...
> How long do you have to wait before the graininess has reliably become 
> unnoticeable?  That's a question I need an answer to before I can use any 
> unbiased renderer for animation work.  I need a renderer that won't give 
> me a picture unless the quality is consistent from one frame to the next.

I saw a commercial (an animation of course) rendered with MaxwellRender the 
other day on TV so whatever theoretical problems exist with unbiased 
renderers and animation seem to be have been solved in production (perhaps 
with the help of a large render farm, but that another issue...). IIRC 
there's a page about animation in the Maxwell manual, you can look it up 
(it's free for download).

G.

-- 
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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47bc9c10$1@news.povray.org...

> If you buy top hardware, model, texture, and drop accurate lighting in 
> your scene, PoV can do it, too.
> The trick is the accurate lighting.  It's not impossible to do in PoV.

Unfortunately, it is.

POV can do a lot of things, but there are many common lighting situations 
that are just out of reach from a practical point of view. It's not just the 
lighting model, but also the texturing model that is insufficient.

When I was busy playing with POV, the key to get good images was to 
precisely to avoid these kind of lighting/texturing situations. There are 
things that POV sucks at rendering unless one spends a lot of time trying to 
find workarounds (or brushing off artifacts...).

The area_illumination feature that Warp introduced in the latest 3.7 beta is 
one of those things that the previous versions couldn't do: of course one 
could simulate it with grids of point lights, but it was just too 
impractical for common usage. Another feature that is sorely missing is 
efficient blurred reflection. There's a trick to do that in POV but the 
results are usable in only certain (limited) circumstances. In modern 
renderers, blurred reflection can be applied to all the materials in the 
scene, thus allowing correct specularity and (inter-)reflections, and this 
adds tremendously to realism.
The beauty of using more advanced renderers (biased or unbiased) is that 
those blocks no longer exist, either because the results are accurate from 
the start (unbiased) or because they are lots of optimisations for speed 
(biased). Just describe accurately your lights and materials, and the system 
works out of the box.

G.


-- 
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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John VanSickle <evi### [at] hotmailcom> wrote:
> How long do you have to wait before the graininess has reliably become 
> unnoticeable?

  I wonder if an automatic measurement and then a threshold couldn't be
developed. For example, if a given pixel hasn't changed color for the
last n rays which have affected that pixel, then that pixel is done.
When all the pixels fulfill this requirement, the image is done.

-- 
                                                          - Warp

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nemesis <nam### [at] nospamgmailcom> wrote:
> >   POV-Ray is simply a great tool to create "3D'ish" images like those.
> > It's easy and fast.

> so, pov-ray will end up its days as a 3D button design tool?  Are 
> pov-ray users ok with that evolutionary idea?

  Why are you trolling?

-- 
                                                          - Warp

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Btw, does unbiased rendering support volumetric lighting? I can't find
any example image in this site nor int the indigo gallery.

-- 
                                                          - Warp

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Gilles Tran wrote:
>> The trick is the accurate lighting.  It's not impossible to do in PoV.
> 
> Unfortunately, it is.
> 
> POV can do a lot of things, but there are many common lighting situations 
> that are just out of reach from a practical point of view. It's not just the 
> lighting model, but also the texturing model that is insufficient.

Impossible and impractical are not the same thing.  Impractical is fine 
for us geeks with lots of time to fiddle on our hands.  XD

> Another feature that is sorely missing is 
> efficient blurred reflection. There's a trick to do that in POV but the 
> results are usable in only certain (limited) circumstances. In modern 
> renderers, blurred reflection can be applied to all the materials in the 
> scene, thus allowing correct specularity and (inter-)reflections, and this 
> adds tremendously to realism.

Ah, I missed reading that 'efficient' bit when I hit reply.  The blurred 
reflection that you can do in POV is physically accurate per 
'micronormals are how you get blurred reflections anyhow'.

'course, until the next version of Moray gets released, I'm stuck with 
good old POV 3.5 anyways...

-- 
Tim Cook
http://empyrean.digitalartsuk.com

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"Darren New" <dne### [at] sanrrcom> wrote in message
news:47bca80c$1@news.povray.org...
> Nekar wrote:
> > Do scientist completely understand all the
> > properties of light?
>
> Pretty much, yes. :-)

But not _perfectly_. if they understood light perfectly there wouldn't be
any search for unified field theories, etc. :o]


--
- Nekar X -

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