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Op 8-8-2022 om 20:06 schreef MichaelJF:
>
> Very nice, indeed. Seems I should take a look into the general
> discussion occasionally. IMO there is a small drawback. The "caustics"
> at the table did not correspond to the light sources within the HDRI
> image. But I'm nitpicking ...
>
You are right as I added an additional light source and the hdri light
sources have been overflooded. I needed it mainly as a backdrop to the
scene.
initially, I wanted to concentrate on the hdr light sources though...
--
Thomas
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Op 9-8-2022 om 14:53 schreef Thomas de Groot:
> initially, I wanted to concentrate on the hdr light sources though...
>
...and when I do, no photons are generated!
I use
photons {
refraction on
reflection on
}
for the sphere with the hdr map, identical to the code for the light
source. Decreasing spacing down to a ridiculously small value doesn't
change anything. I must be missing something here...
--
Thomas
Post a reply to this message
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On 8/9/22 10:50, Thomas de Groot wrote:
> Op 9-8-2022 om 14:53 schreef Thomas de Groot:
>> initially, I wanted to concentrate on the hdr light sources though...
>>
> ...and when I do, no photons are generated!
>
> I use
> photons {
> refraction on
> reflection on
> }
>
> for the sphere with the hdr map, identical to the code for the light
> source. Decreasing spacing down to a ridiculously small value doesn't
> change anything. I must be missing something here...
>
I'm perhaps not following, but...
Taking your hdr sphere to be an actual hollow sphere, you are making it
a photon target for any photon light sources by adding the photon block
above. In other words - as far as I know - there is no way to shoot
photons from other than a traditional light sources.
Aside: I've never tried to shoot photons from a light source inside a
hollow object at the inside surface of that object. I'm not sure it
would work given the how the radial 'shooting pattern' is aimed at
target objects. Perhaps this the reason why you get no photons? Hmm,
maybe a spot light would work... Too long since I've played with photons.
Bill P.
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Thomas de Groot <tho### [at] degroot org> wrote:
> I was happy to read the instructions for a version 3.8 glass material,
> provided by Alain Martel
>
>
https://news.povray.org/povray.general/thread/%3Cweb.62e942de1adc8eb48a3c0aee5cc1b6e%40news.povray.org%3E/
>
> and wanted to try them out myself. This is the result. The different
> variations include air bubbles and the albedo keyword in the cylinder, a
> scattering media inside the ovus, and appropriate fade_color and
> fade_distance for the different objects. The background is a hdr map,
> and a single additional point light are completing the setup.
>
> A big thanks to Alain! This is an excellent starting ground for quality
> glass material indeed.
>
> --
> Thomas
This is why I love working with POV and this community. There's always someone
who has thought about the same problems and is willing to share their experience
(and code!)
-- Chris R.
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Am 09.08.2022 um 17:16 schrieb William F Pokorny:
> On 8/9/22 10:50, Thomas de Groot wrote:
>> Op 9-8-2022 om 14:53 schreef Thomas de Groot:
>>> initially, I wanted to concentrate on the hdr light sources though...
>>>
>> ...and when I do, no photons are generated!
>>
>> I use
>> photons {
>> refraction on
>> reflection on
>> }
>>
>> for the sphere with the hdr map, identical to the code for the light
>> source. Decreasing spacing down to a ridiculously small value doesn't
>> change anything. I must be missing something here...
>>
>
> I'm perhaps not following, but...
>
> Taking your hdr sphere to be an actual hollow sphere, you are making it
> a photon target for any photon light sources by adding the photon block
> above. In other words - as far as I know - there is no way to shoot
> photons from other than a traditional light sources.
>
> Aside: I've never tried to shoot photons from a light source inside a
> hollow object at the inside surface of that object. I'm not sure it
> would work given the how the radial 'shooting pattern' is aimed at
> target objects. Perhaps this the reason why you get no photons? Hmm,
> maybe a spot light would work... Too long since I've played with photons.
>
> Bill P.
Unfortunatelly, Bill seems to be right. I tried a bit, but it seems to
be impossible to persuade a HDRI light to cast photons, so we need POV
4.0 ;)
Best regards,
Michael
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Op 09/08/2022 om 19:09 schreef MichaelJF:
> Am 09.08.2022 um 17:16 schrieb William F Pokorny:
>> On 8/9/22 10:50, Thomas de Groot wrote:
>>> Op 9-8-2022 om 14:53 schreef Thomas de Groot:
>>>> initially, I wanted to concentrate on the hdr light sources though...
>>>>
>>> ...and when I do, no photons are generated!
>>>
>>> I use
>>> photons {
>>> refraction on
>>> reflection on
>>> }
>>>
>>> for the sphere with the hdr map, identical to the code for the light
>>> source. Decreasing spacing down to a ridiculously small value doesn't
>>> change anything. I must be missing something here...
>>>
>>
>> I'm perhaps not following, but...
>>
>> Taking your hdr sphere to be an actual hollow sphere, you are making
>> it a photon target for any photon light sources by adding the photon
>> block above. In other words - as far as I know - there is no way to
>> shoot photons from other than a traditional light sources.
>>
>> Aside: I've never tried to shoot photons from a light source inside a
>> hollow object at the inside surface of that object. I'm not sure it
>> would work given the how the radial 'shooting pattern' is aimed at
>> target objects. Perhaps this the reason why you get no photons? Hmm,
>> maybe a spot light would work... Too long since I've played with photons.
>>
>> Bill P.
> Unfortunatelly, Bill seems to be right. I tried a bit, but it seems to
> be impossible to persuade a HDRI light to cast photons, so we need POV
> 4.0 ;)
>
That was also the conclusion I reached.
POV 4.0, where are you? :-)
--
Thomas
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Op 9-8-2022 om 17:18 schreef Chris R:
> This is why I love working with POV and this community. There's always someone
> who has thought about the same problems and is willing to share their experience
> (and code!)
>
I uploaded my scene file in p.b.scene-files (same subject line).
Enjoy!
--
Thomas
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Le 2022-08-09 à 10:50, Thomas de Groot a écrit :
> Op 9-8-2022 om 14:53 schreef Thomas de Groot:
>> initially, I wanted to concentrate on the hdr light sources though...
>>
> ...and when I do, no photons are generated!
>
> I use
> photons {
> refraction on
> reflection on
> }
>
> for the sphere with the hdr map, identical to the code for the light
> source. Decreasing spacing down to a ridiculously small value doesn't
> change anything. I must be missing something here...
>
The HDR map never emit photons.
What you can do to get caustics from an HDR map is to use radiosity. As
the surface receiving the caustics is close to the objects causing it,
your radiosity settings can still be lenient. You only a small
error_bound value.
Try this as a starter :
global_settings{ assumed_gamma 1
radiosity{
error_bound 0.1 // may try smaller
count 150 1111
low_error_factor 0.2
pretrace_end 0.005
}
}
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Le 2022-08-09 à 08:43, Thomas de Groot a écrit :
> Op 9-8-2022 om 11:40 schreef Mr:
>> Was it slow to render ? There seems to be no anti aliasing.
>>
> I used +a0.3 +am2 +bm2 +bs8 maybe not the best aa setting but I was
> playing ;-)
>
> I think total render time was about 2 hours or a bit more.
>
Just using +a0.1 instead of +0.3 should improve the result and should
not increase the rendering time to much.
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Op 10-8-2022 om 17:42 schreef Alain Martel:
> The HDR map never emit photons.
> What you can do to get caustics from an HDR map is to use radiosity. As
> the surface receiving the caustics is close to the objects causing it,
> your radiosity settings can still be lenient. You only a small
> error_bound value.
>
> Try this as a starter :
>
> global_settings{ assumed_gamma 1
> radiosity{
> error_bound 0.1 // may try smaller
> count 150 1111
> low_error_factor 0.2
> pretrace_end 0.005
> }
> }
Excellent suggestion, concentrating on the caustics! Thanks Alain. This
is the result with:
error_bound 0.01
low_error_factor 0.1
pretrace_start 8/max(image_width,image_height)
pretrace_end 1/max(image_width,image_height)
and stochastic render:
+am3 +a0.01 +ac0.90 +r3
render time was only about 10 minutes.
--
Thomas
Post a reply to this message
Attachments:
Download 'glass_test_04.png' (554 KB)
Preview of image 'glass_test_04.png'
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