On 28-12-2013 1:20, Cousin Ricky wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> On 26-12-2013 20:53, Cousin Ricky wrote:
>>> I just rendered the Lightsys IV examples using POV-Ray 3.7, and this is how
>>> demo_outdoor.pov rendered:
>>>
>>
>>
>> Hmm... /this/ is what I get however.
>>
>> Only added the version and uncommented the assumed_gamma. Did you make
>> other adaptations?
>
> I made no changes to the scene description file.  I put Version=3.5 on the
> command line.  In my version of demo_outdoor.pov, dated 2009 August 11 19:21:16
> (11:21:16 pm UT), the assumed_gamma is not commented out.

why version 3.5? It seems to me that if you want the scene rendered in 
POV-Ray 3.7 that should be the version number... or do I miss something 
here?

>
> What you posted looks similar to my POV-Ray 3.6.1 run, but the trees are in
> different locations, the grassy terrain is different, there is no cliff to the
> right of center, and there is a path going from the center to the lower right.
>

That path is a cliff similar to the one in my image but at another 
position. I cannot explain the differences.

Thomas

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On 28/12/13 08:24, Thomas de Groot wrote:
> On 28-12-2013 1:20, Cousin Ricky wrote:
>> Thomas de Groot <tho### [at] degrootorg> wrote:
>>> Hmm... /this/ is what I get however.
>>>
>>> Only added the version and uncommented the assumed_gamma. Did you make
>>> other adaptations?
>>
>> I made no changes to the scene description file.  I put Version=3.5 on
>> the
>> command line.  In my version of demo_outdoor.pov, dated 2009 August 11
>> 19:21:16
>> (11:21:16 pm UT), the assumed_gamma is not commented out.

I have to agree with Cousin Ricky. I attach two images. The first is
rendered using v3.7 (setting #version 3.7;) and the second using v3.6.1
(setting #version 3.6;)

> 
> That path is a cliff similar to the one in my image but at another
> position. I cannot explain the differences.
> 

I also attach the original scene file (without #version)

John
-- 
Protect the Earth
It was not given to you by your parents
You hold it in trust for your children

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Attachments:
Download 'demo_outdoor.png' (54 KB) Download 'demo_outdoor_36a.png' (226 KB) Download 'us-ascii' (3 KB)

Preview of image 'demo_outdoor.png'

Preview of image 'demo_outdoor_36a.png'

Doctor John <j.g### [at] gmailcom> wrote:
> On 28/12/13 08:24, Thomas de Groot wrote:
> > On 28-12-2013 1:20, Cousin Ricky wrote:
> >> Thomas de Groot <tho### [at] degrootorg> wrote:
> >>> Hmm... /this/ is what I get however.
> >>>
> >>> Only added the version and uncommented the assumed_gamma. Did you make
> >>> other adaptations?
> >>
> >> I made no changes to the scene description file.  I put Version=3.5 on
> >> the
> >> command line.  In my version of demo_outdoor.pov, dated 2009 August 11
> >> 19:21:16
> >> (11:21:16 pm UT), the assumed_gamma is not commented out.
>
> I have to agree with Cousin Ricky. I attach two images. The first is
> rendered using v3.7 (setting #version 3.7;) and the second using v3.6.1
> (setting #version 3.6;)
>
> >
> > That path is a cliff similar to the one in my image but at another
> > position. I cannot explain the differences.
> >
>
> I also attach the original scene file (without #version)
>
I try to render the scene with a modification of camera position ( location
<0,24,-100>*<1,1.25,1> ), here are the two versions of the scene:
First pov3.6

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Attachments:
Download 'outdoor_demov36.png' (382 KB)

Preview of image 'outdoor_demov36.png'

And second Pov3.7:

A lot of differences!

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Attachments:
Download 'outdoor_demov37.png' (424 KB)

Preview of image 'outdoor_demov37.png'

On 12/28/2013 04:24 AM, Thomas de Groot wrote:
> On 28-12-2013 1:20, Cousin Ricky wrote:
>> I made no changes to the scene description file.  I put Version=3.5 on
>> the
>> command line.  In my version of demo_outdoor.pov, dated 2009 August 11
>> 19:21:16
>> (11:21:16 pm UT), the assumed_gamma is not commented out.
>
> why version 3.5? It seems to me that if you want the scene rendered in
> POV-Ray 3.7 that should be the version number... or do I miss something
> here?

Because it was written /for/ version 3.5--or at least seemed so until I 
discovered that the modification date was in 2009.  The intention was to 
invoke any available backward compatibility concessions so that the 
scene would render as intended at the time it was written.  But 2009 was 
during the 3.6 time frame, which shouldn't make all that much of a 
difference from 3.5.

The point is that backward compatibility is not available for the 
crackle pattern, which was the basis for defining the land form.

Anyhow, here is a comprehensive set of POV-Ray 3.7 runs:

demo_outdoor-v3.7-noset.jpg  - no Version on the command line
demo_outdoor-v3.7-set3.5.jpg - Version=3.5 on the command line
demo_outdoor-v3.7-set3.6.jpg - Version=3.6 on the command line
demo_outdoor-v3.7-set3.7.jpg - Version=3.7 on the command line

The only differences I can see are to the brightness of the scene.

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Attachments:
Download 'demo_outdoor-v3.7-noset.jpg' (25 KB) Download 'demo_outdoor-v3.7-set3.5.jpg' (33 KB) Download 'demo_outdoor-v3.7-set3.6.jpg' (32 KB) Download 'demo_outdoor-v3.7-set3.7.jpg' (24 KB)

Preview of image 'demo_outdoor-v3.7-noset.jpg'

Preview of image 'demo_outdoor-v3.7-set3.5.jpg'

Preview of image 'demo_outdoor-v3.7-set3.6.jpg'

Preview of image 'demo_outdoor-v3.7-set3.7.jpg'

"Fractracer" <lg.### [at] gmailcom> wrote:
> And second Pov3.7:
>
> A lot of differences!

Ah, that's because CIE_Skylight.inc uses ambient 1 on the sky dome, which
doesn't work in POV-Ray 3.7 when radiosity is used.  (This is an example of why
I used Version=3.5 on the command line instead of Version=3.7.)

For public include files and demo scene files, I suggest changing all
occurrences of ambient 1 to:

  #if (version < 3.7)
    ambient 1
  #else
    ambient 0 emission 1
  #end

Of course, for your own scene files, where you know you'll be using 3.7, you can
just use emission 1.

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Thomas de Groot <tho### [at] degrootorg> wrote:
> Hmm... /this/ is what I get however.
>
> Only added the version and uncommented the assumed_gamma. Did you make
> other adaptations?

Hey, when I change the camera location to <0,25,-100> and set Version=3.6 (to
keep the skylight), my result is identical to yours (save for the aspect ratio)!

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Thomas de Groot <tho### [at] degrootorg> wrote:
> > What you posted looks similar to my POV-Ray 3.6.1 run, but the trees are in
> > different locations, the grassy terrain is different, there is no cliff to the
> > right of center, and there is a path going from the center to the lower right.
> >
>
> That path is a cliff similar to the one in my image but at another
> position. I cannot explain the differences.
>
> Thomas

Hmm, at the moment I have no resources left to play with things. In the first
thread to this topic by Cousin Ricky from October 2011
(http://news.povray.org/povray.beta-test/thread/%3Cweb.4e8cedc01e77e1ef78641e0c0@news.povray.org%3E/)
Christoph replied

>In a sense yes - the crackle pattern has changed. The general properties
>of the pattern haven't though, so the description in the docs is still
>valid.

>There are a few other random-determined patterns that have changed as
>well in a similar manner. I can't tell off the top of my head though
>which those are.

I have no idea what he ment with "in a sense" really. The crackle pattern is
based upon the calculation of Voronoi diagrams, a (very) well defined issue
within computational geometry. May be the algorithm to calculate Voronoi
diagrams was exchanged with a better one. But as Christoph continues "other
random-determined patterns [...] have changed as well in a similar manner" (the
random part with crackle is the positioning of the points in space to calculate
the Voronoi diagram). That gave me the suspicion that not the pattern are
changed but the noise generator again (last official change after 3.1). That
would explain a lot of the issues you all report here. But it is only a guess
finally.

Best regards,
Michael

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Am 28.12.2013 18:43, schrieb MichaelJF:

>> In a sense yes - the crackle pattern has changed. The general properties
>> of the pattern haven't though, so the description in the docs is still
>> valid.
>
>> There are a few other random-determined patterns that have changed as
>> well in a similar manner. I can't tell off the top of my head though
>> which those are.
>
> I have no idea what he ment with "in a sense" really. The crackle pattern is
> based upon the calculation of Voronoi diagrams, a (very) well defined issue
> within computational geometry. May be the algorithm to calculate Voronoi
> diagrams was exchanged with a better one. But as Christoph continues "other
> random-determined patterns [...] have changed as well in a similar manner" (the
> random part with crackle is the positioning of the points in space to calculate
> the Voronoi diagram). That gave me the suspicion that not the pattern are
> changed but the noise generator again (last official change after 3.1). That
> would explain a lot of the issues you all report here. But it is only a guess
> finally.

I can confirm that it's not just a guess - it is indeed exactly what is 
happening.

(I must confess though that I'm not into details /why/ the random 
generator was changed. Supposedly it was necessary to make the whole 
crackle mechanism work with multithreading at reasonable speed.)

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On 28-12-2013 17:45, Cousin Ricky wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Hmm... /this/ is what I get however.
>>
>> Only added the version and uncommented the assumed_gamma. Did you make
>> other adaptations?
>
> Hey, when I change the camera location to <0,25,-100> and set Version=3.6 (to
> keep the skylight), my result is identical to yours (save for the aspect ratio)!
>

What I had not consciously realized before was that the camera in your 
image happened to be /below/ the landscape. Michael's and Clipka's 
explanation about the random generator make a lot of sense now imho.

Thomas

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