Sun Pool Caustics Revisited with Unbiased TR1

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giannis
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Fri Apr 13, 2012 9:42 am

Dear friends,

you may know that Thea can handle sun pool caustics with its unbiased TR2, which was in fact the subject of an older tech announcement. It was a sad thing though that TR1, a superb unbiased render engine, could not resolve sun pool caustics. For those that are not familiar with the subject, let me say here, that the so called "sun pool caustics" is a particularly difficult lighting transfer to solve with unbiased rendering. This is why it has not been addressed by the vast majority of other commercial unbiased renderers.

The sun pool caustics are such so strong visual cues, that we definitely wanted to see them resolved by TR1 as well. Rendering nowadays an exterior scene with a pool missing caustics, would not make the render look convincing (this is why some users had actually used TR1 and TR2 combined to get fast exterior rendering with the caustics included).

Thus, I am very happy to present a solution to this problem, with TR1 being able now to resolve this lighting (with a restriction*). This makes possible now to render exteriors with these visual cues (much) faster than TR2. Also a requirement for us, not to have any speed penalty in other scenes rendered with TR1, is satisfied. This is why this addition is a win-win enhancement in all cases. :)

Best wishes

* Restriction: the water surface must have zero roughness.
TR1_Sun_Pool_Caustics_15min_quadcore.png
Sun pool caustics rendered with TR1 in the standard example scene that comes with Thea, in 15 minutes on quad core machine.
TR1_Sun_Pool_Caustics_15min_quadcore.png (657.36 KiB) Viewed 13715 times
Pool_TR1_Caustics_01.jpg
Exterior scene rendered with TR1, sun pool caustics included (image kindly provided by "Javadevil").
Pool_TR1_Caustics_01.jpg (120.29 KiB) Viewed 13715 times
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Fri Apr 13, 2012 10:52 am

This is great news. The tenacity at which you guys in the Thea team work towards making the Thea package imitate reality to the finest detail is amazing. Nice work once again. Looking forward to working on a realistic swimming pool one day soon :)
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Pixero
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Fri Apr 13, 2012 11:52 am

Beautiful!
Now, when is TR2 still better than TR1?
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Hieru
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Fri Apr 13, 2012 11:57 am

Great stuff. Looks like we've got a few nice updates heading our way.
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giannis
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Fri Apr 13, 2012 12:02 pm

Pixero wrote:Beautiful!
Now, when is TR2 still better than TR1?
Good question!

TR2 still evaluates robustly more lighting transfers, also related to sun pool caustics (much more complex caustics paths). What we have here is nailing with TR1 the most important visual cue, without resorting to workarounds like rendering the water area with TR2 and merging renders.

Best wishes
Science may limit knowledge but should never limit imagination - Bertrand Russell
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Frankych
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Fri Apr 13, 2012 2:11 pm

Hi Ioannis,
how's this for TR1 caustics 8-) ?

Cheers
Francois

Edit: sorry can't attach image...
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tildee
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Fri Apr 13, 2012 2:58 pm

It would be nice to have a small "chart" as an overview, in which scenes it is better to use which render engine.

That would save many hours of rendering, I think and much more easier for beginners.

I know that sometimes there is no exact answer.

But :shh: : I first have to read the whole documentation, maybe there is something similar...
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Frankych
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Fri Apr 13, 2012 3:16 pm

Here's the image I wanted to post before...
http://www.thearender.com/forum/viewtop ... =92&t=7675

Cheers
Francois
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giannis
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Sat Apr 14, 2012 11:36 am

Frankych wrote:Here's the image I wanted to post before...
http://www.thearender.com/forum/viewtop ... =92&t=7675
Hi Francois

thank you for the picture. I will need to take a look at the scene to say exactly how these caustics are rendered. My best guess now is that there is a transparent/alpha component added to the water surface so that these caustics are visible.

Best wishes
Science may limit knowledge but should never limit imagination - Bertrand Russell
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Frankych
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Sat Apr 14, 2012 12:57 pm

Hi Ioannis,
here's a link to some explanation and the material pack.
http://www.thearender.com/forum/viewtop ... 421#p64421

Cheers
Francois
giannis wrote: Hi Francois

thank you for the picture. I will need to take a look at the scene to say exactly how these caustics are rendered. My best guess now is that there is a transparent/alpha component added to the water surface so that these caustics are visible.

Best wishes
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