Hello Thomas,

thanks again. May be I read this section some years ago but it did not 
came into my mind. The only problem was, that it led me to a wrong track 
regarding the container issues with the steam fog approximation. I will 
not use an emitting media as sun but will follow an approach by Johannes 
Eriksson (May-June competition of the IRTC in 2006). But this is a 
legacy scene and the conversion is not as simple as I expected.

Best regards
Michael

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Le 19-02-28 à 13:25, MichaelJF a écrit :
> I commented the steam fog approximation out, so it rendered a little bit 
> faster. One sees two instances of the same object (it is the example 
> from the tutorials shipped with POV but in a box {-2,2 } instead of a 
> sphere). The only difference is
> 
> object { Sonne
>     scale <500,500,500>*5
>     translate MediaPos
> }
> 
> object { Sonne
>     translate <3,1,5>
> }
> 
> with MediaPos=< 649.685959 , 1442.616855 , 39968.697311 >
> 
> Obviously I will not use it in my scene. It's just a riddle I 
> encountered by chance. I played a little bit with intervals, samples, 
> variance, confidence but without any success. It seems to be due to the 
> scaling alone.
> 
> Best regards
> Michael
Hints :

Don't change intervals from the default of 1. Higher intervals count = 
slower render and may introduce artifacts.

Variance and confidence are used for sampling methods 1 and 2, and are 
not used with method 3 (default).

If you use two value for samples, the second will be silently ignored 
when using method 3.

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> Hints :
> 
> Don't change intervals from the default of 1. Higher intervals count = 
> slower render and may introduce artifacts.
> 
> Variance and confidence are used for sampling methods 1 and 2, and are 
> not used with method 3 (default).
> 
> If you use two value for samples, the second will be silently ignored 
> when using method 3.

Many thanks, I think this issues should be stated in the docs more clearly.

Best regards
Michael

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Am 24.02.2019 um 20:43 schrieb MichaelJF:
> Am 23.02.2019 um 10:12 schrieb Jörg "Yadgar" Bleimann:
>> Hi(gh)!
>>
>> On 22.02.19 20:04, MichaelJF wrote:
>>> Hi to the crowd,
>>>
>>> this image has still a lot of flaws (sun colour and reflections, the 
>>> swan model itself, textures of the cattails) and may be limitations 
>>> to media by POV. media seems to be handling color_maps or 
>>> density_maps different than pigment or texture having no 
>>> interpolation between the map entries but shap edges. This is what I 
>>> derived in a first attempt. Rendering time was a little bit longer (3 
>>> weeks).
>>
>> Just my mustard ;-):
>>
>> The rising fog should be turbulated more, now it looks like small 
>> straight columns of mist... and what about using Chris Colefax's 
>> lensflare macro?
>>
>> See you in Khyberspace!
>>
>> Yadgar
> Hi Yagdar,
> the rising turbulence is just my problem (see the code I posted some 
> minutes earlier). I cannot see a reason to add lens flare to the image. 
> Especially since we have no conversion of the lens flare macros by chris 
> colefax to POV 3.7. They did not work with 3.7 so far. I played around 
> with them to solve this issue a while ago, but failed unfortunatelly.
> 
> Best regards
> Michael
After looking at a lot of photographies of sundowns and sunrises again I 
now understand your recommendation of the lens flare macros. But they 
are still resistant to my conversion efforts. To chance ambient by 
emission simply doesn't work here. If you study his disc approach it 
should work, but there seems to be a hidden secret I have not detected 
so far. With Jaime's lightsys this simple exchange works.

Best regards
Michael

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Am 22.02.2019 um 20:04 schrieb MichaelJF:
> Hi to the crowd,
> 
> this image has still a lot of flaws (sun colour and reflections, the 
> swan model itself, textures of the cattails) and may be limitations to 
> media by POV. media seems to be handling color_maps or density_maps 
> different than pigment or texture having no interpolation between the 
> map entries but shap edges. This is what I derived in a first attempt. 
> Rendering time was a little bit longer (3 weeks).
> 
> Best regards
> Michael
> 
Hi to the crowd again,

since I lost all the code of the original approach of this image due to 
a headcrash, I had to restart this scene from scratch. Only the 
erroneous density I posted here was left and the corrections Thomas and 
Alain proposed of course. Here is the actual WIP. I wondered how a white 
sun can cast yellow beams, but I took this RL image

https://de.wikipedia.org/wiki/Sonnenaufgang#/media/Datei:Sonnenaufgang_penon_de_ifach.jpg

as a basis for the sky_sphere, the sun, and its reflections. I failed to 
model this thin slice of white in the reflections in the original 
photography so far. But I think to "forget" it, is a venial sin.

I plan to add some pines, cattails, gras, broom, and the swan of course, 
but nothing more. The steam fog over land will be invisible after the 
addition of the plants (hope so). Additional suggestions are welcome as 
ever.

At the moment the rendering time is manageable: some hour with 16 
threads at 3.6 GHz (intel core i9).

Best regards
Michael

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Attachments:
Download 'gelaende_pov_scene13.png' (849 KB)

Preview of image 'gelaende_pov_scene13.png'

MichaelJF <mi-### [at] t-onlinede> wrote:
> I failed to
> model this thin slice of white in the reflections in the original
> photography so far. But I think to "forget" it, is a venial sin.

Maybe you can add a cylinder of media that is bisected by the water's surface?
Or layer an AOI texture onto the water?

Other than that, I'd look to prior art in the archives, or in other graphics
groups...

Great job so far!   :)

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Op 16/08/2020 om 18:27 schreef Bald Eagle:
> MichaelJF <mi-### [at] t-onlinede> wrote:
>> I failed to
>> model this thin slice of white in the reflections in the original
>> photography so far. But I think to "forget" it, is a venial sin.
> 
> Maybe you can add a cylinder of media that is bisected by the water's surface?
> Or layer an AOI texture onto the water?
> 
> Other than that, I'd look to prior art in the archives, or in other graphics
> groups...
> 
> Great job so far!   :)
> 
> 
> 

Great job indeed. First thing I thought concerning this issue was: Tom 
York's diffuse modulation. Maybe it can help you: see his comment in the 
following thread:

http://news.povray.org/povray.newusers/thread/%3Cweb.4393311ed86e519e4114da700@news.povray.org%3E/?ttop=338362&toff=650

-- 
Thomas

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Am 17.08.2020 um 08:45 schrieb Thomas de Groot:
> Op 16/08/2020 om 18:27 schreef Bald Eagle:
>> MichaelJF <mi-### [at] t-onlinede> wrote:
>>> I failed to
>>> model this thin slice of white in the reflections in the original
>>> photography so far. But I think to "forget" it, is a venial sin.
>>
>> Maybe you can add a cylinder of media that is bisected by the water's 
>> surface?
>> Or layer an AOI texture onto the water?
>>
>> Other than that, I'd look to prior art in the archives, or in other 
>> graphics
>> groups...
>>

>>
>>
>>
> 
> Great job indeed. First thing I thought concerning this issue was: Tom 
> York's diffuse modulation. Maybe it can help you: see his comment in the 
> following thread:
> 
>
http://news.povray.org/povray.newusers/thread/%3Cweb.4393311ed86e519e4114da700@news.povray.org%3E/?ttop=338362&toff=650

> 
> 
Thank you both for your suggestions. May be the addition of an other 
media may cure the problem but I had a lot of difficulties to adjust the 
media as they are so far and will not risk to disturb them by another 
one. The other approach proposed by Thomas is the use of a texture_map 
to the lake similiar to the construction of my sky_sphere. Fortunatelly 
air has no ripples or waves and is more predictable as water. May be I 
must have more patience in modellng a filtering disc with a proper 
scaled hole

disc {
    0,z,20000, unkown hole size
    pigment { colour srgbf <1,0.847,0.333,1> }
    rotate <0,0,-90-degrees(acos(vnormalize(SolarPosition).z))>
    translate SolarPosition/10000
    no_image no_reflection
}

Best regards
Michael

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Op 17/08/2020 om 19:11 schreef MichaelJF:
> Am 17.08.2020 um 08:45 schrieb Thomas de Groot:
>> Op 16/08/2020 om 18:27 schreef Bald Eagle:
>>> MichaelJF <mi-### [at] t-onlinede> wrote:
>>>> I failed to
>>>> model this thin slice of white in the reflections in the original
>>>> photography so far. But I think to "forget" it, is a venial sin.
>>>
>>> Maybe you can add a cylinder of media that is bisected by the water's 
>>> surface?
>>> Or layer an AOI texture onto the water?
>>>
>>> Other than that, I'd look to prior art in the archives, or in other 
>>> graphics
>>> groups...
>>>

>>>
>>>
>>>
>>
>> Great job indeed. First thing I thought concerning this issue was: Tom 
>> York's diffuse modulation. Maybe it can help you: see his comment in 
>> the following thread:
>>
>>
http://news.povray.org/povray.newusers/thread/%3Cweb.4393311ed86e519e4114da700@news.povray.org%3E/?ttop=338362&toff=650

>>
>>
> Thank you both for your suggestions. May be the addition of an other 
> media may cure the problem but I had a lot of difficulties to adjust the 
> media as they are so far and will not risk to disturb them by another 
> one. The other approach proposed by Thomas is the use of a texture_map 
> to the lake similiar to the construction of my sky_sphere. Fortunatelly 
> air has no ripples or waves and is more predictable as water. May be I 
> must have more patience in modellng a filtering disc with a proper 
> scaled hole
> 
> disc {





> }
> 
> Best regards
> Michael
> 

Best approach I guess is the one made by Jaime Vives Piqueres. I have 
been working with his code lately for a couple of months (adding foam to 
sea water for instance; see my 'Nature Beyond' thread).

See the following link for the technical aspects:

http://www.ignorancia.org/index.php/galleries/old-images/sea-buoy/

-- 
Thomas

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> Thank you both for your suggestions. May be the addition of an other 
> media may cure the problem but I had a lot of difficulties to adjust the 
> media as they are so far and will not risk to disturb them by another 
> one. The other approach proposed by Thomas is the use of a texture_map 
> to the lake similiar to the construction of my sky_sphere. Fortunatelly 
> air has no ripples or waves and is more predictable as water. May be I 
> must have more patience in modellng a filtering disc with a proper 
> scaled hole
> 
> disc {





> }
> 
> Best regards
> Michael
> 

When working with disc, don't forget that they have an interior that is 
not limited to the visible part.
Whenever you have media, you need to add hollow to any disc in the scene.

This :
disc{0 y 10}
have the same interior as this :
plane{y 0}

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