"St." <dot### [at] dotcom> schreef in bericht news:4509911a@news.povray.org...
>
>
>    That's what I wanted to say! Really, I admire Thomas' work, but I too 
> have no experience with Rad, and consequently, don't know what an 
> 'artifact' is. When they're spoken of, I always find it hard to see what 
> the author is seeing.
>
I did not answer fully your comment. Sorry for that.
Apart from the column shafts, you can see those black spots towards the 
base, on the horizontal surface just below the torus. Those are definitely 
artefacts. So, although I feel not happy about the shafts, the image is 
almost there.

Thomas

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This is almost 'perfect' :-)
Still a bit of artifacts visible, but not much.
Essentially, what I have changed since the preceding render are:
increasing nearest_count to 10
increasing error_bound at 0.5 in the first pass
increasing low_error_factor to 0.9
increasing count to 250
decreasing recursion_limit to 2
decreasing brightness to 0.8 in the second pass

...and I gained a couple of hours at the first pass! So I can use that to 
increase count even more.

Again, many thanks to all for your very helpful comments!!
People! listen carefully to your betters!!!  :-)

Thomas

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Attachments:
Download 'Eavesdropping_wip07.jpg' (52 KB)

Preview of image 'Eavesdropping_wip07.jpg'

"Thomas de Groot" <t.d### [at] internlnet> wrote in message 
news:450ac173@news.povray.org...
> This is almost 'perfect' :-)

    Agreed. This is looking much better! And yes, I now see where the 
artefacts were.  ;)

     But, you've got to do something about that texture (on the lower 
pillars), because it looked SO good in your other image! Perhaps some kind 
of procedural crackle might do it? (Not sure).

       ~Steve~




> Thomas

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Thomas de Groot wrote:

> ...So.... it is a story, a myth, a dream... whatever you want... :-)
> Still, I feel it important that the elements seem to go together, and blend 
> into a credible scene.
> 
Thanks to Gena, we know it's a "Capriccio"

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Thomas de Groot wrote:

> Again, many thanks to all for your very helpful comments!!
> People! listen carefully to your betters!!!  :-)
> 
>
Oh, and what do you know? I have been "eavesdropping" on *that* little 
conversation.

With the technical problems gone, this image takes on a compelling 
narrative interest. Figure gestures, camera angle, and so on. Nice work. 
  Don't know where all this is coming from, or going to, but I love it. 
  Are your images collected anywhere such that we might see the development?

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Thomas de Groot wrote:
> This is almost 'perfect' :-)
> Still a bit of artifacts visible, but not much.
> Essentially, what I have changed since the preceding render are:
> increasing nearest_count to 10
> increasing error_bound at 0.5 in the first pass
> increasing low_error_factor to 0.9
> increasing count to 250
> decreasing recursion_limit to 2
> decreasing brightness to 0.8 in the second pass

It looks much better (although difficult to judge at this small size) 
but under the aspect of the argument i gave concerning the adaptive 
error_bound using a higher one in the pretrace than in the final trace 
is counterproductive.  Of course the adaptation will automatically 
increase it in the final pass but this will make it slower than 
necessary.  If you set the starting value of the adaptation to the same 
as in the pretrace this will probably make it quite a bit faster and not 
much worse (although it is difficult to say for sure). Since there have 
not been a lot of tests made with the adaptive error_bound it might be 
interesting to see the (non-jpeg-compressed) results of this in 
comparison.   If you could quote the number of samples taken in pretrace 
and in the final pass that would also help to say if these assumptions 
are correct.

BTW using different brightness in two passes is handled by POV-Ray AFAIK 
but there is not much point in doing this.

Christoph

-- 
POV-Ray tutorials, include files, Landscape of the week:
http://www.imagico.de/ (Last updated 20 Aug. 2006)
MegaPOV with mechanics simulation: http://megapov.inetart.net/

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"Jim Charter" <jrc### [at] msncom> schreef in bericht 
news:450af2a3$1@news.povray.org...
> Thomas de Groot wrote:
>
>> ...So.... it is a story, a myth, a dream... whatever you want... :-)
>> Still, I feel it important that the elements seem to go together, and 
>> blend into a credible scene.
>>
> Thanks to Gena, we know it's a "Capriccio"

Thanks Jim! That is exactly the right description. Forgot about Gena's.

Thomas

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"Jim Charter" <jrc### [at] msncom> schreef in bericht 
news:450af426$1@news.povray.org...
.
>
> With the technical problems gone, this image takes on a compelling 
> narrative interest. Figure gestures, camera angle, and so on. Nice work. 
> Don't know where all this is coming from, or going to, but I love it. Are 
> your images collected anywhere such that we might see the development?

Thank you indeed, Jim! It is going in the direction I want it to go.
I have no idea where the image is coming from. It is one of those typical 
hunches/visions I often have about scenes, stories, projects. Most of the 
time, it comes to nothing; sometimes I try to keep a record on them; in a 
few instances they turn into images, stories, or projects. It depends very 
much on how compelling the hunches really are. Sometimes the vision is so 
compelling that I work on it for a couple of days/weeks, totally mesmerized, 
like if somebody was dictating me what to do (sounds familiar?) and then 
most often, it remains dormant for a long time.... or forever.
Quite possibly, this images is going to turn into a short story one day, or 
become part of a larger whole. I don't know. With a friend, we write an 
unending stream of short stories (in Portuguese), sometimes based on 
randomly selected old photographs or pictures. It's fun to do. 
Interestingly, before even knowing about Gilles Tran's Book of Beginnings, I 
had started something similar but with finished very short texts around an 
image. It too started suddenly as a hunch.
I am working on a website where (part of) my work will be on display. I 
admit that I started it already years and years ago, but since a few weeks 
it seems to pick up speed. So... be patient.

Thomas

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"St." <dot### [at] dotcom> schreef in bericht news:450ae56f$1@news.povray.org...
>
>     But, you've got to do something about that texture (on the lower 
> pillars), because it looked SO good in your other image! Perhaps some kind 
> of procedural crackle might do it? (Not sure).
>
Steve, I am not sure I get your meaning. The texture is not looking so much 
different from the non-radiosity image I believe. There is already a (agate) 
turbulence/normal controlling the layered, averaged texture (visible on the 
closest pillar to the left). Towards the middle distance this becomes 
necessarily less visible. The same would hold for a crackle (for instance), 
so you would not really see it. And then, radiosity is also playing its part 
here.

Thomas

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"Christoph Hormann" <chr### [at] gmxde> schreef in bericht 
news:eeesuu$npn$1@chho.imagico.de...
> Thomas de Groot wrote:
>> This is almost 'perfect' :-)
>> Still a bit of artifacts visible, but not much.
>> Essentially, what I have changed since the preceding render are:
>> increasing nearest_count to 10
>> increasing error_bound at 0.5 in the first pass
>> increasing low_error_factor to 0.9
>> increasing count to 250
>> decreasing recursion_limit to 2
>> decreasing brightness to 0.8 in the second pass
>
> It looks much better (although difficult to judge at this small size) but 
> under the aspect of the argument i gave concerning the adaptive 
> error_bound using a higher one in the pretrace than in the final trace is 
> counterproductive.  Of course the adaptation will automatically increase 
> it in the final pass but this will make it slower than necessary.  If you 
> set the starting value of the adaptation to the same as in the pretrace 
> this will probably make it quite a bit faster and not much worse (although 
> it is difficult to say for sure). Since there have not been a lot of tests 
> made with the adaptive error_bound it might be interesting to see the 
> (non-jpeg-compressed) results of this in comparison.   If you could quote 
> the number of samples taken in pretrace and in the final pass that would 
> also help to say if these assumptions are correct.
>
Thanks Christoph. I much appreciate your comments as I feel that I still 
have a lot to learn about this matter. Forgive me if I seem obtuse, but I 
find this a difficult matter to understand, despite the excellent tutorials, 
by the way, of you and others.
Let's see if I get this correctly.
Concerning error_bound, what I should do is (for instance):
error_bound 0.5 //first pass
error_bound {0.5 adaptive 1.5, 20} //second pass
OK? The quality of the results might then dictate using 0.5 or lower (or 
higher, to see where acceptable boundaries are).
My initial assumption was that by making error_bound adaptive (at least in 
the final pass) megapov would determine automatically what the necessary 
values were, thus gaining time and quality.

I saved the message files fortunately. These are the number of samples taken 
during pretrace:
Radiosity samples calculated:           424116 (1.34 %)
Radiosity samples reused:             31208079
  Samples (final trace)                  59336
  Samples (recursion 1)                  78012
  Samples (recursion 2)                 346104

And these of the samples taken during the second pass:
Radiosity samples calculated:            65094 (1.16 %)
Radiosity samples reused:              5549135
  Samples (final trace)                  64420
  Samples (recursion 1)                   7061
  Samples (recursion 2)                  58033

With the changes to error_bound, I shall make a new render and post both 
images (the present one and the new one) together in png format.

> BTW using different brightness in two passes is handled by POV-Ray AFAIK 
> but there is not much point in doing this.
>
Oh? I confess I followed the teachings of  Tim Nikias in this matter.

Thomas

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