C4D + Redshift - How to fix your caustic render!

Follow Me
/ taylor_kenny
/ the_astropath
/ tk_mograph
Here's more information on the "Warm Edge Lighting Effect" chrisbrejon.co... scroll down to the "Warm Edge" section.
Being able to art direct your caustics is important when trying to hit a specific look in your render.
In this example I created a simple still life render. There are a few mason jars on a wood table that I want to reflect caustic rays. These caustic reflections will be created by an infinite light that's pointed through the window.
I've added RS object tags on the mason jars and turned on the "Cast Caustic Photons" option in the visibility overrides.
For lighting I have two infinite lights for a "Warm Edge effect". I'll link to further information about that lighting technique in the description.
Both lights have the "Emit Caustic Photons" option turned on and are emitting 200,000,000 photons each. I should note that I had trouble previewing this in the render view for some reason and could only see the final results in the picture viewer. At lower numbers of photons, 10,000,000 - 20,000,000 for example the render view worked fine and that should be more than acceptable for setting up your scene before the final render. I set both light's intensity multipliers to 1.25. My "Caustic Blur Radius" was set to .2.
Additionally I needed to adjust the settings of the glass material for both the window and jars in order to get a more accurate result. In the material settings I've disabled the "cull dimm internal reflections" under the optimizations tab. I set the shadow opacity to 0.2 in the "advanced tab" and set the refraction-transmission color to around 96% so it's not completely transparent.
First I'm going to render this without the window and it's frame for reference. (Hit render) You'll see that the jars are reflecting the caustics like I wanted but now we're missing the window and it's shadows in the scene.
Lets add the window and it's frame back into the scene. On the window geo I've added a redshift tag and turned on the "Cast Caustic Rays visibility" override under global illumination. (Hit render) All of a sudden our scene is very bright and we've lost the caustic reflections from the jars amongst the brightness.
Now that the window is casting caustics, it's doubling the intensity of the light that passes through the window. There's one emission of rays for the initial lighting and another for the caustics. Since there are no intricate patterns in the window's glass to refract the caustic rays you get this over exposed look.
Now lets turn off "Cast Caustic Rays" and the "Visible to Caustic Photons" options. What this does is tells the window geometry to NOT cast caustic photons and makes it invisible to the photons being emitted from our infinite light. Now the photons will pass through the window as if it didn't exist.
Lets see how this looks. (Hits Render)
Finally the caustics are reflecting off the jars properly and our window geo is in the scene to give us the light effects we're after.
_________________________________
Thanks for watching this short example of Redshift Caustics in action. If you found this video helpful please hit that like button down below and subscribe for more tutorials! If you have any questions drop them down below and I'll do my best to answer them.
I'll see you in the next tutorial!
#c4d #cinema4D #redshift #render

[@tondann]

Just what I needed to render some beautiful water caustics! thanks

[@zacharywalsky6722]

Thank you for teaching me about Caustics!

[@the-astropath]

Your welcome friend!

[@art_means_artificial]

lovely! keep updating your stuff on youtube!

[@the-astropath]

That's the plan, I have more videos in the works!

[@art_means_artificial]

​@@the-astropath thanks mate! subscribed! if you can, could you make about arnold denoiser for animation? if it is in your plan in near future. cheers

[@the-astropath]

@@art_means_artificial funny you ask I have one on my channel already - it may be a little dated now but it should definitely get you up and running.

[@art_means_artificial]

@@the-astropath hm I am not able to find ... could you point me which one? thanks!

[@the-astropath]

Ah I see you said Arnold I thought you meant Redshift. I do not have a video on the Arnold one but I can put that on the list!

[@JordEmery]

Thanks a lot !

[@fabriziotorchia8376]

Beautiful tutorial. I recently switched to redshift, but caustic photons doesn't work !! Do you by any chance know the reason for this problem? I have a 2080 rtx and I have updated all the drivers, but nothing.