1. The POV image appears to have some radiosity artifacts. Any that appear
in the Bryce image (as graininess) will be due to the number of rays used
(114). Again, in POV, the default radiosity settings were plonked in.

2. POV has taken the background white into account and so the ground is
brighter. In Bryce the atmosphere is off and the Sun too.

3. When developing the POV scene, prior to adding the radiosity features,
the sphere's roundness was still in visible due to shadow. However, in
Bryce, once the ambience was whacked up, the shadow was lost.

4. POV relies on the diffuse element of a texture, whereas Bryce uses the
ambient element. One can specify in Bryce an ambient colour and an ambient
level. In POV, one merely specifies an ambient colour. However, I used
"ambient 1" in POV as it seemed to eliminate more of the self-shadow that
was not visible in Bryce.

Conclusion: The Bryce version looks more pleasing but I suspect that there's
a good reason they call it "true ambience" rather than radiosity. I should
imagine that with some knowledgeable tweeking in POV, those artifacts could
be got rid of.

PS. After creating these 2 images I decided to determine the most accurate
POV camera angle for emulating the Bryce camera. With only about a pixel's
difference the angle appears to be 48 degrees - how this relates to Bryce's
FOV of 60 degrees I don't know, but when viewing the Bryce camera from above
it does appear to be approx 45 degrees.


The Bryce camera viewing angle in POV appears to be 48 degrees. Bryce has a
default of

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Attachments:
Download 'POV_radiosity.jpg' (30 KB) Download 'Bryce_true_ambience.jpg' (42 KB)

Preview of image 'POV_radiosity.jpg'

Preview of image 'Bryce_true_ambience.jpg'

IMBJR wrote:
> 
> 4. POV relies on the diffuse element of a texture, whereas Bryce uses the
> ambient element.

This isn't entirely true. In POV, objects with an ambient value will 
glow when radiosity is used.

> One can specify in Bryce an ambient colour and an ambient
> level. In POV, one merely specifies an ambient colour.

I suspect this distinction is semantic, as using numbers with higher 
values in POV will produce more ambience; essentially, the color is ALSO 
the level. You may find it intuitive to multiply your color vectors by a 
  value, which will have the effect of strengthening or weakening the 
ambience while retaining the same ambient color.

> Conclusion: The Bryce version looks more pleasing but I suspect that there's
> a good reason they call it "true ambience" rather than radiosity. I should
> imagine that with some knowledgeable tweeking in POV, those artifacts could
> be got rid of.

Radiosity tweaking can often produce good results, yes.

Without the benefit of your scene code, or knowing the "default" 
radiosity settings you're using offhand, it's impossible to suggest 
specific problems or improvements, but based on your other image posts I 
suspect that a poor understanding of POV-Ray on your part is causing you 
to write scenes that don't imitate your Bryce scenes as well as you 
think they should.

-Xplo

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"Xplo Eristotle" <xpl### [at] infomagicnet> wrote in message
news:3d69c985@news.povray.org...
>
> Radiosity tweaking can often produce good results, yes.

error_bound 1 might do the trick.

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Xplo Eristotle <xpl### [at] infomagicnet> wrote in message
news:3d69c985@news.povray.org...
> IMBJR wrote:
> >
> > 4. POV relies on the diffuse element of a texture, whereas Bryce uses
the
> > ambient element.
>
> This isn't entirely true. In POV, objects with an ambient value will
> glow when radiosity is used.
>
> > One can specify in Bryce an ambient colour and an ambient
> > level. In POV, one merely specifies an ambient colour.
>
> I suspect this distinction is semantic, as using numbers with higher
> values in POV will produce more ambience; essentially, the color is ALSO
> the level. You may find it intuitive to multiply your color vectors by a
>   value, which will have the effect of strengthening or weakening the
> ambience while retaining the same ambient color.
>
> > Conclusion: The Bryce version looks more pleasing but I suspect that
there's
> > a good reason they call it "true ambience" rather than radiosity. I
should
> > imagine that with some knowledgeable tweeking in POV, those artifacts
could
> > be got rid of.
>
> Radiosity tweaking can often produce good results, yes.
>
> Without the benefit of your scene code, or knowing the "default"
> radiosity settings you're using offhand, it's impossible to suggest
> specific problems or improvements, but based on your other image posts I
> suspect that a poor understanding of POV-Ray on your part is causing you
> to write scenes that don't imitate your Bryce scenes as well as you
> think they should.

I think it is more the case that the 2 will prolly never be truely married.
Of course, some greater understanding will reveal what the unbridgable
difference is.

>
> -Xplo
>

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3d6959fa@news.povray.org...
> Conclusion: The Bryce version looks more pleasing but I suspect that
there's
> a good reason they call it "true ambience" rather than radiosity.

The reason is that the Bryce folks know very well what good radiosity/GI
support is and that they know that what they implemented in Bryce 5 is
somewhat experimental. They'd like to implement GI and photon mapping (and
these could be in a future version of Bryce - no rumour here, got this from
a direct source) but they want to do it in a way consistent with what their
user base expect.

> I should
> imagine that with some knowledgeable tweeking in POV, those artifacts
could
> be got rid of.

High sample count, low error bound, lots of RAM and long hours of twindling
thumbs.

G.

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

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IMBJR wrote:
> >
>>Without the benefit of your scene code, or knowing the "default"
>>radiosity settings you're using offhand, it's impossible to suggest
>>specific problems or improvements, but based on your other image posts I
>>suspect that a poor understanding of POV-Ray on your part is causing you
>>to write scenes that don't imitate your Bryce scenes as well as you
>>think they should.
> 
> I think it is more the case that the 2 will prolly never be truely married.
> Of course, some greater understanding will reveal what the unbridgable
> difference is.

I'm not sure how you expect to "marry" POV-Ray and Bryce, considering 
that they don't share the same rendering engine, or even the same 
rendering method (Bryce being mainly a scanline renderer if I'm not 
greatly mistaken), and that they're both using techniques which may not 
realistically model physical phenomena (meaning that they're not 
necessarily even TRYING to achieve the same thing).

With that said, I think my reproduction of your glass sphere 
demonstrates that it's possible (and even easy - most of my time on that 
scene was spent moving objects around) to get very similar results to 
Bryce if you know what you're doing.

-Xplo

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Xplo Eristotle wrote:
> With that said, I think my reproduction of your glass sphere 
> demonstrates that it's possible (and even easy - most of my time on that 
> scene was spent moving objects around) to get very similar results to 
> Bryce if you know what you're doing.

Uh, shouldn't it be the other way 'round?  Trying to achieve POV-like
scenes in Bryce? ;)

-- 
Tim Cook
http://empyrean.scifi-fantasy.com
mirror: http://personal.lig.bellsouth.net/lig/z/9/z993126

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GFA dpu- s: a?-- C++(++++) U P? L E--- W++(+++)>$
N++ o? K- w(+) O? M-(--) V? PS+(+++) PE(--) Y(--)
PGP-(--) t* 5++>+++++ X+ R* tv+ b++(+++) DI
D++(---) G(++) e*>++ h+ !r--- !y--
------END GEEK CODE BLOCK------

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Timothy R. Cook wrote:
> Xplo Eristotle wrote:
> 
>> With that said, I think my reproduction of your glass sphere 
>> demonstrates that it's possible (and even easy - most of my time on 
>> that scene was spent moving objects around) to get very similar 
>> results to Bryce if you know what you're doing.
> 
> Uh, shouldn't it be the other way 'round?  Trying to achieve POV-like
> scenes in Bryce? ;)

Probably so; in my limited experience Bryce seems to be a mediocre 
renderer at best (not to mention slow). Sadly, that's not what's being 
discussed here.

On that note, a while back someone said in response to all the copycat 
renders that were being posted here that someone should make a POV-Ray 
scene that everyone ELSE would be trying to copy. I thought it was a 
good idea, but no one seems to have done it (which is not to say that 
people haven't made things with POV-Ray that are WORTH copying!).

-Xplo

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Xplo Eristotle <xpl### [at] infomagicnet> wrote in message
news:3d6a7ef8$1@news.povray.org...
> Timothy R. Cook wrote:
> > Xplo Eristotle wrote:
> >
> >> With that said, I think my reproduction of your glass sphere
> >> demonstrates that it's possible (and even easy - most of my time on
> >> that scene was spent moving objects around) to get very similar
> >> results to Bryce if you know what you're doing.
> >
> > Uh, shouldn't it be the other way 'round?  Trying to achieve POV-like
> > scenes in Bryce? ;)
>
> Probably so; in my limited experience Bryce seems to be a mediocre
> renderer at best (not to mention slow). Sadly, that's not what's being
> discussed here.

Slow? That really does depend on what you are doing with it. Most of my
stuff comes in well under a couple of minutes, but then I like the
minimilist scene.

As for mediocre, that's perhaps a bit too sweeping a statement. Sure there
are somethings in Bryce (the sky, metaballs) that really could use
improvement, but as a hobbyist's renderer it really fits the bill.

>
> On that note, a while back someone said in response to all the copycat
> renders that were being posted here that someone should make a POV-Ray
> scene that everyone ELSE would be trying to copy. I thought it was a
> good idea, but no one seems to have done it (which is not to say that
> people haven't made things with POV-Ray that are WORTH copying!).
>
> -Xplo
>

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3d6a7ef8$1@news.povray.org...
> I thought it was a good idea, but no one seems to have done it (which is
not to say that
> people haven't made things with POV-Ray that are WORTH copying!).

It has been done now.

Original in Pov-Ray
http://www.zazzle.com/posters/gallery/product.asp?product%5Fid=70002764

Later remade by someone else with Lightwave (?)
http://www.zazzle.com/posters/gallery/product.asp?product%5Fid=70008908

G.

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