Improved Shadow Catcher

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Tue Jun 30, 2015 12:47 pm

Dear friends,

as you probably know, our shadow catcher implementation is basically an "ambient occlusion"-like shadow catcher that is computed based on only the IBL image. Many users have been asking for a possibility to have the shadow catcher working for sun as well. Also, for those looking for higher quality, the ambient occlusion shadows were not really that convincing, especially if the IBL image was not uniform in terms of lighting intensity.

Creating a shadow catcher working realistically inside the render itself is not easy, as one may imagine. The result can also be less than perfect in many situations. Indeed, that's why in v1.4 we went directly to supporting shadow channel (for Presto), which supports all lights and it is the best for those who use lot of post production.

Still, having an integrated shadow catcher working out of the box, is never a bad idea. So we thought, it is about time to deal with this matter once and for all! And that's exactly what we have done, making a list of advances that altogether contribute to a substantially improved shadow catcher:
- New shadow catcher works not only now for IBL images but also for sun-sky (and omni point lights in general).
- New shadow catcher takes into account the directionality of the IBL images, so as to produce much more realistic shadows.
- We introduced the horizontal infinite plane supported now by Presto as well, for easier workflow (instead of creating custom rectangular floor, scaling it, etc.).
- New shadow catcher can work also in conjunction with a reflective BSDF. This gives the ability to have reflections on the shadow catcher plane, with arbitrary (user defined) colors, reflectivity and roughness.

Here is a comparison render between shadow catcher in v1.4 and improved one. Notice how the shadows in v1.4 are uniform and weak but in the new shadow catcher implementation, there is strong directionality in visual accordance with the reflections on the objects.
Shadow catcher in v1.4, weak ambient-occlusion-like shadows.
New shadow catcher with stronger shadows following the lighting direction.
Same scene as above but also with reflections added on the shadow catcher.
New shadow catcher with reflections.
As always, the renders have been created by Patrick. Note: the noise seen under the central statue is not engine noise but it is coming from the scanned model geometric fluctuations.

Best wishes
Science may limit knowledge but should never limit imagination - Bertrand Russell
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Tue Jun 30, 2015 2:23 pm

I am waiting for this upgrade for some time, but I was confident! Great Giannis! :clap: :clap:
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Tue Jun 30, 2015 3:24 pm

It's also looking very good. This is indeed a nice addition!
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Tue Jun 30, 2015 3:40 pm

Just recently I ran into these problems and all of them seem to be solved now :-)

:thumbup: :thumbup: :thumbup: :thumbup:

Cheers and thanks,

Peter H
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Tue Jun 30, 2015 5:39 pm

:clap: Awesome new toy. Thanks a lot. :D

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Tue Jun 30, 2015 10:59 pm

Having these real shadows makes it look likes it's really there. Awesome job. :thumbup:
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Wed Jul 01, 2015 12:28 am

Great News! Thank you so much! :clap:
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Wed Jul 01, 2015 1:56 am

This is looking really promising !!
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Wed Jul 01, 2015 8:03 am

Just awesome Giannis !!! Cheers! :clap: :clap: :clap:
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Wed Jul 01, 2015 10:02 am

Waw, "Joli" Giannis ;)