Silverwing Quick Tip: Understanding Caustics (Or why caustics are so hard to render)

This tut is made with Octane Version 2022.1_R5 and Cinema 4D Version 2023.1
Hello everyone.
This week a Day early as I am invited to a birthday Party tomorrow yay.
Its a very theoretical video this week as it lets you peek behind the inner workings of a renderer and tries to answer the question of why Caustics are so darn hart to render in most of todays render engines.
P.s. leave a comment if you have any good Idea for a future quick tip / tut.
0:00 Intro
1:00 Establishing the Baseline
1:58 What Light is doing in Reality
3:14 The CGI Process
5:46 Caustics in Reality
6:17 Caustics in CGI
8:00 What happens with "Fake Shadows"
9:11 Looking at Photon Caustics
10:24 Examples in 3D
11:27 Explaining "Caustic Blur"
13:40 Photon Tracer "Photon Gathering Radius"
15:45 Outro

[@ThePuka]

Otoy owes you. You continue to educate on a fairly deep level about the use cases of octane features. Ideally I would have always liked video materials on each feature of octane that was called up inside the app. The manual is ok but often you need to know why you use a feature at all. Something like Jake In Motions amazing AE breakdown of every effect would help octane users so much. I hadn’t considered how the caustics were calculated, glad to understand now. Be interesting to see how this develops with the brigade transition.

[@SilverwingVFX]

Thank you very much! Yeah having a video on every Feature sure would be a super nice thing. But it is also a lot of work and tedious to maintain. In the meantime you can request tuts and quick tips for the stuff you think is important for you ☺️

[@proceduralnodes3d]

Great tutorial!! You really explained why there is an issue and how the photon kernel helps remedy it.

[@SilverwingVFX]

Thank you. Great to hear that I managed to bring the thought across 🙌

[@vladolareanu]

Exactly what I needed now! Thank you :)

[@SilverwingVFX]

Oooh, that´s nice to hear. Cheers 🙌

[@oursonwelles]

Always the best 3D content here 👌

[@SilverwingVFX]

Trying my best! Glad to hear that 😊

[@amisheetrit2119]

Raphael, as always you keep things interesting by explaining how its actually works in real life+cgi. Thank you so much for your time & effort! this Tutorial is amazing

[@SilverwingVFX]

Thanks a lot Ami. Appreciate your nice words. Maybe I should have explained what caustics are in the first place... 😇 Anyway, very glas you liked it!

[@zotake]

I was waiting it! You are killing with those Quick Tips! Thanks again for sharing it.

[@drbolick]

Nice work! Thank you!

[@alexp5054]

Brilliant stuff, really good info thanks

[@impylse]

Wow! always wondered how fake shadows and caustic blur worked... thank you Raphael!

[@SilverwingVFX]

Very glad you liked it. With those technical explainer videos, there are always 1000 more things one could explain in more detail. So its nice to hear you found it satisfactory.

[@DomZeal]

Really good explanation

[@SilverwingVFX]

Very glad to hear that. I was not sure how understandable it was 😇

[@ThomvanVliet]

Always learn something new, even going in to this video thinking I won't need caustics information I still learned about fake shadows and caustic blur, incredible!

[@SilverwingVFX]

Ha ha this is soo cool. I always try to sprinkle in helpful bits here and there. Glad it worked!

[@anastasiaantoshkina7720]

Thank you very much :)

[@nicolasnayok]

Amazing! Thanks

[@MGrillo3D]

Just what I need to see, thanks for making Sir!!!

[@SilverwingVFX]

Thank you very much for watching and commenting kind sir 🎩

[@goner13]

Everytime you add another piece to my knowledge :D

[@SilverwingVFX]

That´s so nice to hear. Cheers and thanks a lot 🙏

[@afewhourslater_dion]

sooo great lecture. You did amazing thing

[@SilverwingVFX]

Thank you very much. Great to hear that you liked it 🙌

[@darkworx-films]

I like your tutorials very much. I always watch them during my break on monday. I am also interested in another fusion tutorial regarding multipasses and how to combine them from the ground up. Thus Aces with a model with more layers to it, dif dir/ind refl dir/ind etc etc, the way to combine them exactly is something interesting to me and perhaps you would love to elaborate on that as well:D keep up the good work!!!

[@SilverwingVFX]

Hey Nick, that´s super nice to hear that you made a habit out of watching my vids 🙌 Thank you very much for your suggestion for another fusion tut. Generally fitting together passes should be super easy. Most of them get added (Refl Direct / Inderect) for example The same like I showed in the first Fusion tut with the light passes. To be honest, I don´t use such "complex" comping techniques myself. I usually get good results by just combining the light passes tweaking them a little and adding overall grad / look to my comp 😅 The only other thing I use from time to time is render layers. Like what I did in the Tutorial for AE. Would it be of interest to you to see that done in Fusion? Cheers and a good start into the week to you!

[@hihihing7302]

quite interesting!! Thanks bro!

[@SilverwingVFX]

Hey hey. Wow you are on a comment spree. Thank you for all of those!

[@hloshak]

Brilliant video man!

[@SilverwingVFX]

Thank you so much!

[@bharat5194]

Thanks

[@SilverwingVFX]

You are very welcome!

[@emmanuelchacon8900]

Master Silverwing.

[@SilverwingVFX]

Thank you 😳 🙏

[@DIRK_H.]

very good explanation, thanks a lot!!!🙂🙂🙂

[@SilverwingVFX]

Thank you very much. Glad to hear you found it useful 🙌

[@bulba1561]

big brain explanation. another banger bro

[@SilverwingVFX]

Thank you very much. So glad to hear you like it!

[@bulba1561]

@@SilverwingVFX i love these types of tutorials with the diagrams/charts

[@Clemyfourtwenty]

Yay happy fun learning time!

[@SilverwingVFX]

Ha ha nice to hear 🙌

[@paulpaulsen416]

Thank you! 👍 Herzlichen Dank! 👍

[@SilverwingVFX]

You are very welcome 🤗

[@jj89677]

Oh mannnn, vielen Dank! Ich lern so viel durch dich *_*

[@SilverwingVFX]

Das ist sooo co zu hören! Vielen Dank für Dein Kommentar!

[@vinicimmm]

nossa, muito obrigado, esse vídeo é uma verdadeira aula.

[@SilverwingVFX]

Thank you very much. Much appreciated!

[@yassinrupp146]

yeh, nice one! thank you.

[@SilverwingVFX]

Also thank you for watching and commenting!

[@alokitpathik811]

excellent so happy from OTOY for this update can we have complete scene tutorials like using this photon update on a perfume bottle !!

[@SilverwingVFX]

Yes, I think it helps mostly with beauty product and beverage commercials. For bigger scenes there are some things still missing imho. As control via light / hdri to cast caustics etc. Also an option to fine tune HDRIs. Some of them can cause quite some photon fireflies.

[@gv0zdysh0k]

Thank you so much! I'm amazed by your tutorials/researches. Last time I asked you about intersecting and overlapping volume objects, I want to add to the list of questions the topic of noises, especially in dark scenes. Sometimes it's impossible in octane to render without noise no matter how many samples do you use, how it is? I'm a corona user as well and rendering one picture for 8 hrs I'm sure that it will have no noise at all, but in octane 16000 passes with all maximum values I have no guarantee that it will be clean - that is so embarrassing and annoying

[@SilverwingVFX]

Hey and thank you for your comment. The intersecting volumes suggestion is still on my tut list. Though as I usually rather rarely deal with this, I would have to do some research to be really sure. For now, as I probably said last time, for overlapping volumes, make sure that the step length is the same for all of the overlapping ones. About Noise: That one os really tricky to answer as it really depends on the scene and the lighting. Geberally what Octane does not like is small bright light sources, non rough surfaces. In general high energy always causes fireflies and everything to divert / spread the energy is a help to reduce noise Also of couse Adapive Sampling and GI Clamp (the default here is really high in Octane and I believe is much lower on Corona) With the right precautions Octane in almost all cases renders rather quick and noise free. But maybe this is another good foundation for an Octane optimizing tut. Hope those few hints help a bit. Other then that you are welcome to write me an email and send me some example renders of scenes that I can take a look at. The mail address is on my website. Cheers and a fantastic start into this week to you!

[@gv0zdysh0k]

@@SilverwingVFX thank you som much! You are great!

[@sunbok.]

🔥🔥🔥🔥

[@SilverwingVFX]

🙏🙏🙏🙏

[@johnford8425]

do you ever use the photon tracer on larger scenes like a swimming pool? I am finding they work quite well on smaller scenes but for archviz work they work, but have issues - lots of black squares that many times to not resolve.

[@johnford8425]

actually - I just realized - the problem was multiple cards - if I use only one gpu, the problem is gone - in case anyone else runs into this.

[@SilverwingVFX]

@@johnford8425 Hey John, thank you very much for your comments. I am in contact with the dev team about this issue. Hopefully it can be fixed soon. Other then that. I use photon tracing only if I need very detailed caustics. Otherwise you would get longer render times for nothing. Since I am almost always doing small scenes besides from tests I have not had the opportunity to use it on bigger scenes like the mentioned pool.

[@Amorstopineed]

Hello raphael, its very intersting, i really want to make such interesting casutic scenes - but not sure which render works better- redshift or octane, you prefer octane to redshift regarding this difficult, detailled scenes?

[@SilverwingVFX]

Hey there. I think the best way to determine which renderer is best for you is to try both and then decide which one you can operate best. There are differences between Octane and RS of course. Octane is more restrictive to physical behavior while you can fake a lot more in RS what also gives you more flexibility if you need it. It´s pretty much down to the user and to his needs and what workflows he uses. Hope that helps you to make a decission. Raphael

[@Amorstopineed]

@@SilverwingVFX thank you very much!

[@austinpinilla7409]

I recently updated to octane plugin for c4d 2022.1-R5, and tested out what you did here with a platonic (both filled and hollow), and I didn't get a different in caustics or visuals from PT and Photon. Any suggestion on what could be the problem?

[@SilverwingVFX]

Have you enabled photon caustics in the material you used on the platonic. Its in the Index tab and called "allow caustics" also make shure "fake shadows" is turned off. Hope that helps!

[@user-vh3gu3di5y]

Hello! I'm leaving a comment because I'm curious. 1. Photon Tracing seems to take longer rendering time than Path Tracing. Is that correct? 2. Photon Tracing seems to have much better caustic representation than Path Tracing. Then, is there no need to use Path Tracing? I'm Korean and it's a shame that I'm not good at English. So I don't fully understand this deep and great tutorial. I'm still reading and watching it. Thank you.

[@SilverwingVFX]

Hey there and thank you for your comment: Photontracing = Normal Pathtracing + Photons Therefore it renders longer for situations where you do not need accentuated caustics. Rendering without strong caustics = Pathtracing Rendering with strong emphasis on caustics = Photon Tracing I hope that makes it clearer. Greeting to Korea and a great weekend to you!

[@user-vh3gu3di5y]

@@SilverwingVFX I understand perfectly! Thank you so much🥹👍

[@SilverwingVFX]

@@user-vh3gu3di5y 👍 🙌

[@cowboytanaka6675]

was ist das allererste was sich jemand der in C4D interessiert ist angucken sollte? Ich gucke mir VFX gerne an aber hab keine ahnung wie es geht und wie gesagt du hast es durchgespielt also gibts sowas wie "VFX for dummies"?

[@SilverwingVFX]

Ha ha vielen Dank. Ich offe, dass es zumindest für die Leute, die Octane machen, ein wenig Aufschluss bringt. C4D selbst hat natürlich nochmal sehr viel Quick Tip Potential. Freut mich immer, von Dir zu hören. Grüße und ein tolles Wochenende Dir!

[@DommageCollateral]

hey ich arbeite mehr mit blender, houdini, unity und threejs...aber hast du einen discord?

[@SilverwingVFX]

Hey hey, danke für Dein Kommentar. Sorry, hab keinen eigenen Discord-Channel. Bin aber im Octane Render Official. Allerdings nicht wirklich aktiv dort. Bei Fragen darfst Du mir aber gerne eine Mail schicken!