VFX Artist Explains the HARDEST Visual Effect to Make

Squarespace ► Head to squarespace.com/corridorcrew to save 10% off your first purchase!
Join OUR Exclusive Streaming Service ► www.corridordigital.com/
THIS EPISODE ► Wren explains the most scientifically difficult visual effect to pull off - light caustics. But what exactly makes caustics so difficult to simulate?
Check out OTOY for the latest in unbiased GPU rendering ► home.otoy.com/
SUPPORT ►
Join Our Website: bit.ly/Crew_Membership
Instagram: bit.ly/_Corridor_Instagram
Twitter: bit.ly/_Corridor_Twitter
Buy Merch: bit.ly/Corridor_Store
OUR GEAR, SOFTWARE & PARTNERS ►
Our Go-To Gear: bhpho.to/3r0wEnt
Puget Systems Computers: bit.ly/PC_Puget_Workstations
ActionVFX: bit.ly/TheBest_ActionVFX
Lighting by Aputure: bit.ly/CORRIDOR_LIGHTS
Cinema4D: bit.ly/Try_Cinema4D
Nuke by The Foundry: bit.ly/Nuke_Compositing
Insydium: bit.ly/Insydium_Plugins
Octane Render by OTOY: bit.ly/Octane_Wrender
Boris FX - Mocha, Sapphire & Continuum: bit.ly/2Y0XLUX
Motion Captured with Xsens Suit: bit.ly/Xsens_MoCap_Suit
Reallusion: corridor.video/Reallusion_3Ds...
Unreal MegaGrant: bit.ly/Unreal_MegaGrant
MUSIC ►
Epidemic: bit.ly/Corridor_Music click this link for a free month!

[@crazybobby14]

Imagine that the reason for "Avatar: The Way of Water" to have taken so many years to be released was due to the caustics finally finished rendering.

[@silverhawkscape2677]

Possible.

[@cyanjackson7689]

honestly makes a lot of sense LOL

[@austinsavage5962]

That would be hilarious if they made that beautiful film like a year after the first one but the rendering just took forever

[@TheNamesNobody]

A huge portion of making films like this is waiting for rendering regardless..

[@Dynelegacy]

good thing there wasnt a power outage at 99 percent XD

[@SirPembertonS.Crevalius]

I always loved seeing the ins and outs of VFX, it's a perfect example of "if you do things right, people won't be sure you've done anything at all."

[@SAbdullah03]

I'm taking this quote

[@feniksix31]

One of my favourite quotes from Futurama 😁

[@killakori]

"I was god once." "Yes, I saw. You were doing well until everyone died."

[@TheSpoonDeLauro]

I just rewatched this episode and thought the same thing haha!

[@craigrussell3062]

GOD: Bender, being God isn't easy. If you do too much, people get dependent on you. And if you do nothing, they lose hope. You have to use a light touch, like a safecracker or a pickpocket. BENDER : Or a guy who burns down a bar for the insurance money. GOD : Yes, if you make it look like an electrical thing. When you do things right, people won't be sure you've done anything at all. The quote gains in majesty from its context

[@jgust]

Just watched avatar the way of water and it’s definitely simulated. The light patterns changes accurately when a creature is disturbing the water surface. It’s crazy how good it looks.

[@SkulShurtugalTCG]

How do you know they didn't just take a camera to Pandora and film it for real?

[@justinyearing3489]

There’s a video about it. They actually took the actors and put them in a Vfx suit, then dropped them into a tank of water.

[@salimsawandi9829]

i think they used real water and edited to fit with the characters movements

[@maBasmi]

@@salimsawandi9829 not true. everything is rendered, especially the water. There are two shots I think (an eye close up and one indoor scene (?)) that are not rendered. all outdoor scenes are practically completely CGI

[@salimsawandi9829]

@@maBasmi proofs? you have the production files?

[@bentheboss3734]

omg I cant believe mark is actually doing normal stuff for the channel this is so cool. this just made corridor crew 10x better.

[@2teepeepictures382]

The history of long hair in animated movies. Simulating hair has been such an interesting subject. I think it would make a pretty good video.

[@donhoolieo4896]

Hair, water, and glass in my opinion, are the hardest things to simulate. I agree with you. I find this stuff fascinating when you dig into the details on why simulating something would be hard. It’s almost reverse engineering reality.

[@SirWrender]

Ooooooo I like this idea!

[@2teepeepictures382]

@@SirWrender I know. I feel like hair was the thing that everyone always talked about in the special features of animated films. Then after brave came out people just stopped talking about it. I wonder if the issues are still issues now or if it’s an old problem. I heard it described sort of like an atomic bomb. Each hair strand bumps into each other building up momentum until the simulation just freaks out for no apparent reason. I feel like monsters Inc. was another ground breaker in that department.

[@2teepeepictures382]

@@SirWrender ha! Just realized who this was. If you’re looking for ideas than a video exploring the question of whether it’s physics or relatedbility that make hand-to-hand combat for almost human shaped CG creatures believable. For example something that is shaped like a bear would not be able to generate much power using tae kwon do kicks. Would it look more believable to have realistic technique or realistic weight distribution?

[@captainviggo4575]

I remember watching behind-the-scenes videos of Final Fantasy: The Spirits Within back then, talking about how maybe like half of the rendering time of the movie was just for Aki's hair. It also explains why all the other characters have short hair, hair tied back or even no hair…

[@carlosnascimento9269]

"Real life runs constantly in real time without ever crashing." Well, I would certainly hope so. Great video Wren.

[@MaxBrix]

"As the frame rate shifts so do we." Einstein, sorta.

[@ShaneCourtrille]

Er.. how would we know? maybe when you forget where you were going that's a crash :D

[@HAWXLEADER]

Maybe it crashed multiple times, got rebooted and restored to the last auto save, you can never know!

[@H3xx1st]

Brains crash all the time, seizures. Some people have them due to light. Its people that crash not the world, it kinda makes me think where the rendering is happening, in the world or in our minds.

[@yubelious5584]

People who create worlds of their own merit have more right to speak on reality than I ever will.

[@TheBrownieSundownHD]

These Wren videos are some of the highest quality videos out there. His understanding and ability to explain these concepts is so unreal. Great stuff!

[@CaptainOblivion]

I think the main case where simulated caustics for an underwater shot would be more notably different than the gobo option, is when the thing catching the caustics is very close to the surface of the water. The parts of the dinosaur that are right up against the water would catch very different caustics than the parts further away, not just in brightness but in sharpness as well. If you move the dinosaur further underwater, the difference between the close parts and the far parts becomes less significant, and the result looks a lot more like the gobo.

[@overanimated626]

it's a shame to come back to a video i used to enjoy, now knowing this company is so comfortable with art theft and is even complicit in it.

[@secretsandwich9693]

Same here

[@grinchfingers6741]

I’m glad he looks like he is enjoying it 😆

[@jonathanarocho893]

I'm so confused. Why is he there? It's funny lol but I don't understand

[@herlastborn]

@@jonathanarocho893 He lives there now. They don't let him leave.

[@jadonyohannan5864]

@@jonathanarocho893 Markiplier is a fan of this channel and the Corridor Team, and got in contact them a little over a month ago where they (including Markiplier) reacted to his KZbin series "Markiplier in Space." He had another video with them "VFX PRO Must Guide Noob Through CGi Hell" where he has become their intern and I guess he just shows up now here and there 😂

[@The_Razielim]

Man I missed Wren's deep-dives into very specific topics. I enjoy most of the content on this channel, but those hit particularly hard for me since he usually does either a science-y topic, or something crazy and obsessive about a sci-fi franchise... in either case, I love the effort you (Wren + the whole team involved) put into these vids.

[@anirudhnavin4568]

His deep DIVES ?? XD

[@The_Razielim]

@@anirudhnavin4568 that wasn't an intentional pun but goddammit I hate you for pointing that out lmao

[@rickydo6572]

Ironically enough, the dude in your pfp has a very complicated relationship with water lol

[@The_Razielim]

@@rickydo6572 Tumbling... burning with white hot fire...

[@anirudhnavin4568]

@@The_Razielim All in a day's work

[@_Prince_Of_Darkness]

As far as I'm concerned I saw the trailer of Avatar the way of water multiple times and each time I caught some new details but talking about Caustics, yes they were both a mixture of original shots under water and perfect cgi because one can clearly see the rays of light in the trailer but that doesn't happen in real life and the Caustics get dull as depth increases also the clarity of water is the biggest factor in play here, cleaner the water more crisp are the Caustics

[@demondaviee1005]

Congratulations, Wren. I think this is the best video you've ever done. Well done, you did a great job putting this together

[@branbroken]

When you consider if someone were to actually run that 11 year render, by the time it finishes you would probably be able to run an equivalent render in an hour with the advances in both hardware and render algorithms, probably also with some sort of AI enhancement thrown in.

[@bloodypommelstudios7144]

Yeah I've thought that about stupidly long renders before. If it takes 18 months of tech progress to double your rendering speed you're better off waiting 18 months if a render takes more than 3 years. I guess if you ever found yourself in a situation like that you'd start rendering the first third of the animation and when the new system arrives use that to render the the remainder.

[@MrGamelover23]

@@bloodypommelstudios7144 or just use render farms.

[@ryanmccampbell7]

Quite likely that the entire process will just be AI (neural networks) eventually.

[@UltraNoobian]

A similar concept is the Wait Calculation for Interstellar travel. Do you depart now with current technologies, or wait until you get even faster spaceships?

[@theastronomicalmouse1828]

You can't wait for technology. It's why "The Works" was never completed - it would have been the first full 3D rendered movie, but the continual resetting because of technological advances meant it was never completed.

[@mrandersen6872]

Wow I can't believe wren was able to speak under water so clearly!!! Fantastic job!

[@zonesproductions]

He's a pro

[@melliecolesg231]

That's a secret power only VFX artists have.

[@LuisSierra42]

He was also able to breathe

[@mrandersen6872]

@@LuisSierra42 truly a master of his craft.

[@adeoyesimeon3821]

The cameraman is the true god here

[@redglassesart]

I love these kind of videos from Corridor it’s fun and educational and Wren does a great job explaining how or why something works as it does

[@Insertnamesz]

I love Wren's solo vids. Learnt a lot once again. Keep it up.

[@goodwincek]

happy Wrendnesday to us

[@danelyman]

Wren is honestly a great educator. Has a passionate energy, knowledgeable background, and ability to simplify complicated ideas. He really could have his own education channel and I bet it'd be huge!

[@VMYeahVN]

He 100% has Bill Nye energy and i love it.

[@azimhulaimi]

@@VMYeahVN omg you're right now that you mentioned it! haha

[@bcgolfguide]

yep!

[@tylerismyname]

This was fascinating and I feel like contained knowledge applicable outside of just caustics. Loved the deep dive!

[@RobertsMind]

Thank you for this video. I am working on learning how to make water in Unreal Engine 5 right now. I have only been in the learning to render and model space for about 2 months and I think I missed my calling. I have been a software and web applications engineer for 26 years and it doesn't bring me near the pleasure I am getting from the open world game I am building and all of the rendereing, modeling, and animation that I am having to learn to build it. Thank you for all of the great content you have and will produce. Keep up the great work and keep inspiring everyone that watches your videos. If I ever had the chance I would love to come work with you guys and learn some of the craft and tricks of the trade from you and the rest of the Corridor Crew.

[@shubhajitghosh123]

Take it this way... The movie Avater 2 is truly coming after 13 years, so maybe they shot it that time and... Waited 11 years for the render!

[@hiteshadari4790]

lmfao makes sense

[@Tooth_Fairy]

Your fbi agent doesn't like that you've revealed confidential info mate!

[@mookymookymooo]

Whooaaa

[@jainikpatel575]

Whoo, can be true.

[@themannyzaur]

Woah woah woah how did you know?

[@StewartFletcher]

That montage of all the glass renders was honestly one of the most beautiful things I've seen

[@ZazivartumaV2]

adult swim vibes

[@johnlol2507]

music choice at 10:35 is amazing im so glad to see drum and bass lol cause a lot of mixes on yt have old renders

[@PavlosPapageorgiou]

I was working on that in uni decades ago. The reason caustics are hard is there's no obvious way to trace a path from the camera to the light through 3rd surfaces. Normally you trace from camera to surface and then you trace in the direction of each light to see if the patch of surface is illuminated. But if light is to come through reflection or refraction it could be coming through any path. You'd have to render the entire scene from the PoV each surface patch just to calculate 2nd level lighting. Or you could trace photons forward from the light, have them deposit on surfaces randomly like textures, and then trace the scene from the camera and hope you got enough photons. That's the slow technique that I worked on way back. You could do better with fancy sampling and compression of photons, or some differential approximation of path tracing, which I'm guessing form part of the new renderer.

[@jasonchiu272]

Wren: "It will take 11 years to render it!" AI: Two more papers down the line. Take it or leave it.

[@matthahne]

WHAT A TIME TO BE ALIVE!

[@DoctorNemmo]

You know, I'm something of a fellow scholar myself

[@thespacemanfil4921]

Two minute papers but all of the videos are longer than two minutes

[@maxmuller445]

My papers almost flew away

[@hmm7458]

isn't it carzy we all got the reference 🤣

[@vanshgarg5514]

Wren : finds an amazing shot Wren a few minutes later: realizes the shot was simpler than imagined Also Wren : fuck it, I wanna try the hard way and see it's worth it And that's why we love this channel

[@spiderjerusalem8505]

"we"? I don't :/

[@BilliesAltfroid]

@@spiderjerusalem8505 "We" are the ones who love their content. Why would he count you as US anyways? lol

[@spiderjerusalem8505]

@@BilliesAltfroid, he didn't specify the group of people he meant be "we", I had to ask. Pretty depressing thought, being a part of "you" 😔

[@FloopDeMoop]

@@spiderjerusalem8505 Aww, sad troll is sad. Why waste your time watching videos you don't like? Go be sad elsewhere.

[@EkardRimidalv]

@@spiderjerusalem8505 You need help

[@Boredman567]

I think the gobo shot can be improved just by altering the actual video used for the light. So if you want to change the light falloff, you could try and change the light gradients and shapes, and adjust the intensity and contrast of the light source.

[@DjamTG12345]

These videos made by wren are some of my favorite videos on corridor

[@wunkskorks2623]

4:15- that guy is SO stoked to talk about his work. That’s a rare gift, to have your work be something that excites you that much.

[@JMPERager]

Wish I had that, or if I already do, could find that thing NOW. I'm in desperate need of direction in my life...

[@debtoralive4693]

If you or I were to have a creative job like his, I'm sure we'd be as excited as he is. I know I feel really great when I'm creating art.

[@henrikmikaelkristensen4784]

Wish we could see it in their products too.

[@bazinga2]

You have officially won in life when you go into a field of work that you love. No matter your age it’s never too late to pick up a new hobby and potentially go into the field!

[@BookmansBlues]

Jules is awesome, and very passionate about these kinds of thing.

[@xodiaq]

The randomness on the simulated caustics is why they feel better to my eye, the gobo is very cyclical. If it was an isolated beauty shot, the simulated will make a HUGE difference, but in the Dino scene it’s probably not worth it. Really cool topic!

[@catsnorkel]

it is also not too hard to create gobos that are procedural and do not loop like this.

[@chopsuey4698]

@@catsnorkel exactly

[@VertexPlaysMC]

you could make better gobo caustics if you adjust the settings or use different water footage.

[@propyro85]

@@catsnorkel I know precious little about VFX, but would it be possible to create a gobo that's the the length of time you need for your caustic effects? Like you have a 2 minute scene where you need that effect, so you make a 2 minute gobo, so there's no obvious loop in it? Would that be any easier or is that pretty much working out to the same effort to fake it from the start?

[@catsnorkel]

@@propyro85 yes that's technically possible, but by that point it would probably be a lot easier and more efficient to do it procedurally

[@StephanBuchin]

10:36 Wow! The results are amazing and they look so real. The morphing purple sphere is deeply pleasing to the eye.

[@rebirth4119]

I find it interesting that caustic filters of animation and film is like the filtering of convolution reverb on audio. You can take the room sound reflection response of something and put it on audio to simulate that a recording is taking place in a specific place like a bathroom or a tunnel.

[@williammanning5066]

Much of computer graphics can be viewed as 2d signal processing

[@Mystikan]

I've always simulated water wave caustics simply by using a Voronoi noise shader in World space under a Colorizer filter in the Luminance channel. The gradient of the colorizer is then mapped to an inverse-square falloff (I use a Python node to generate the gradient knots from a formula) to give it the sharp contrast between the bright thin regions and dim falloff characteristic of these kinds of caustics. It looks very close to real, and adds zero to the render time.

[@rano12321]

6:50, you can get that, physically correct caustics in Blender as well, and Blender has had that feature for over 6 months now and it's using a much more complex and advanced algorithm than photon mapping, it's called "manifold next event estimation" and it's based on a research paper released by weta digital, so there's a good chance they've used that method to calculate real caustics in avatar 2 by using their own renderer called Manuka. Great video nonetheless.

[@intgr]

Though mnee calculates the caustics within the shadow of the object only, whereas photon mapping produces more realistic caustics inside and outside of the shadow

[@thespinningcube]

@@intgr I guess luckily for Avatar, everything under the ocean surface is in shadow.

[@RandomNirvanaSXE]

I have a manuka tree in my yard.

[@TiagoTiagoT]

You can use LuxCore on Blender to get more complete caustics. The material system is only partially compatible with Cycles materials though.

[@FaZekiller-qe3uf]

@@RandomNirvanaSXE ok

[@kilgo5439]

4:27 OMG! ITS MARK!! So happy to see him on corridor crew!

[@danieltodorovic3879]

Dude that caustic render sequence with the drum n bass was so sick

[@Jet7Wave]

After diving into making a washing machine tech visualization for school with simulated water exploding out of the drum and rendering it all with VRay with both caustics and motion blur I can certainly relate. This was a lovely video to see and man, I gotta check out Photon Tracer.

[@McCallahanIndustries]

Wren emerging from the deep is a callback to Sync when the main character wakes up in the ocean.

[@DLCS-2]

I thought it was how we evolved from the sea

[@dilanrajapaksha]

Man I loved Sync best show Corridor ever made

[@LaSerpentDEden]

Sync is such a good movie

[@derigel9783]

Oh God, how long ago was that show?

[@evolutionarytheory]

As a professional rendering engine developer, can I just say guys, this is a REALLY good video. Well done. Also, it's cute that you think 100 hours is slow to render. r.e. Avatar, WETA can certainly render caustics of the nature you showed "for real". Their renderer Manuka has a very flexible raytracing architecture that they can tune per shot. They have also released a phenomenal number of advanced papers recently for rendering complex light-transport scenarios, so I would guess that yes, those shots proabably were fully physically-plausible caustic renders (probably also with some creative license thrown on top for good measure).

[@kentslocum]

I imagine they had to improve their rendering game for all of the underwater scenes in Avatar 2.

[@Deliveredmean42]

So this is why it took them a decade to get Avatar 2 release...

[@wjrneo2]

@@kentslocum And they aren't doing it even on a high end single workstation. No single system today can compare with a state of the art Render Farm.

[@Idiomatick]

They would have also had access to ML tweaked versions to cut render times like probably the one Wren talked about.

[@evolutionarytheory]

@@Idiomatick ML isn't used as much as you might think in production rendering. IMO it's a hugely over-hyped technology. It's too difficult to control, and when it doesn't work, it's useless. So most of the time we specifically choose not to use it, especially for things like caustic rendering that demand reasonable frame-to-frame coherency, something ML is often terrible at.

[@seanloughran6714]

That was awesome! Loved the deep dive into this niche area!

[@rushingninja6640]

Wren is always so fun to watch. i was barely able to follow as couldnt really understand and yet he still makes it so enjoyable and easy to watch :)

[@somedude8604]

Mark casually being an intern always cracks me up. Loved the video, very interesting topic.

[@linkz101]

Love to see intern Markiplier doing the hard work

[@being47]

I was beginning to believe no one saw him.

[@xenon9200]

@@being47 i was gonna say the same thing, lmao

[@justinmcgough3958]

Glad you said something cause I wasn't sure if I was just being dumb or if that was actually Markiplier

[@cliffemall7984]

@@justinmcgough3958 For real, I was so confused because it came out of nowhere.

[@cli]

i was like holy shit is that markipoo

[@madoss_1838]

This is something all of the content creators should adopt in their videos " Enthusiasm " Cause when you are actually having fun doing what you're doing the viewer feels the energy and it prevents him from moving an inch. I personally enjoyed every second of this video.

[@MrTrollstash]

How old are you?

[@madoss_1838]

@@MrTrollstash 😅😅 why is that?

[@MrTrollstash]

@@madoss_1838 Curiosity

[@madoss_1838]

@@MrTrollstash I am 21 mate 😁

[@MrTrollstash]

@@madoss_1838 Damn only one year older XD and to think that once 20 was a big number. Anyway what I wanted to say was that it is a normal thing on the youtube platform to be enthusiastic about something 😂 Tho yes not much, I have to agree. But if you are interested in game development or stuff like that then lmk and I can hook u up with some of the best channels 😁

[@debtoralive4693]

I have watched several of your videos now because I'm interested in the process and it's apparent limitations and well, all computer generated graphics. In this video I got a better sense of what you really mean when you say rendering, which helps me understand so much more. I just have one question: you seem to have a lot of fun there, which is great, but how do you guys ever have the time to get all these great videos done???

[@NourArt02]

Wren: I'm gonna render this scene at 16000 samples. Also Wren: Why is it taking so long ?

[@poonamr9870]

BRUH XD

[@niemanickurwa]

ikr :D

[@TINYArmy]

seriously...watching him turn on EVERYTHING (GI, Photon Emission, AO, DoF, etc.) and running the entire scene at super high sample rates and telling the world that refractive caustics take forever to render was a bit cringe. 100hr 720p render....you'd be fired from any lighting/rendering department for that kind of move.

[@donflamingo795]

Bruh moment

[@farpurple]

@@TINYArmy 100 hours is just a bit more than 4 days afk, it isn't so much

[@ponta2852]

This is honestly one of the most interesting things I've seen in a while, caustics are so mesmerizing! Would totally watch if you went more in depth on other types of effects!

[@jonyconde]

Amazing information on this video as always thank so much guys. 🙏😍

[@Kajed8963]

Damn it feels like forever since the last "Wren explains cool shit" video. I missed this.

[@d.b.4671]

Wren: "surely they're not called caustics because they burn things, right?" Also Wren: proceeds to burn things with caustics (In fairness, I also didn't make the connection until he said the exact words "catch things on fire".)

[@richardpike8748]

Wow me neither! Thanks for pointing that out

[@willbe3043]

That's a really interesting point!

[@alexivanescu8682]

most under appreciated comment ever!

[@atheistlinguist542]

The term "caustic(s)" literally comes from the classical Greek word for "burn."

[@thewolfstu]

I actually used this vid as inspiration after watching it the first few times and ended up using caustics in some background renders for my art and in a piece I recently did for Valentine's day I even used it to simulate an old CRT TV and it's been fun messing with caustics in Blender.

[@Nevarent]

This is such an informative video, driven by the true power of science: curiousity and willingness to experiment. I love it.

[@legofisch9753]

I second what a few others also said: The differences between gobo-caustics and simulated ones are probably way more noticeable once anything interacts with the cause of the caustics. In the case of water the surface. Like an underwater shot of someone breaching the surface from below. The caustics on the part of the body still underwater would change as the surface would get distorted. And also there will be bubbles the light has to go through. Same for let's say a boat passing over your underwater scene. It would not just be a shadow as another gobo layer on top of the "fake" caustics. The wake of the boat would change the caustics. Although in contrast to the first example it would probably be reasonably easy to record the caustics patterns of a model boat in a pool to simply get a better "fake" layer. Oh and my guess on why the simulated magnifying glass looked slightly different is, that you modelled a perfect lens. But real lenses, especially cheaper ones, often have slight imperfections in their surfaces. And the refractive index varies as well. There is a reason you pay several 100$ for good lenses that size.

[@Timberwolf581]

"my guess on why the simulated magnifying glass looked slightly different is, that you modelled a perfect lens." I think the same goes for the other examples he made. They all look a little too neat and too sharp.

[@lucadeandraderibeiro]

I'm researching caustics and its 3d rendering at university and I must say: this was a great video. It was very informative without being overcomplicated. Also, the message about how computer graphics is all fake is super important because it's easy for us artists to forget that cgi is entirely simulation, that, for instance, no rays or photoms are really being traced or that no particle or wave is really interacting with matter and transfering energy to it etc. I say its easy to forget because I myself did it, focusing too much on physical accuracy when in the end rendering algorithms are just mathematical models that try to replicate real phenomena (and generally from the limited pov of a camera). It doesn't matter how good they are, they will never reach reality. At most they will seem visually close enough. When we remember that, we are free. Free not just to take some shortcuts as shown in the video, but free to explore cgi as what it is, a simulation, and embrace both the limitations of innacuracy and its hidden powers as part of the artwork, as a way of subverting the laws of physics and, because of that, creating better and more powerful scenes (yet physically innacurated) and telling better and more touching stories with them.

[@DeGuerre]

I'm reminded of a Usenet discussion from the 90s when "A Bug's Life" and "Antz" were out around the same time, and a lot of people were talking about which film looked more "realistic". A renderer engineer from Pixar ended the discussion with a three word sentence: "The ants talk."

[@jjbarajas5341]

Fake particle physicist

[@fish2785]

Just the random montage with the breakcore is awesome

[@samuelebarberi8631]

i liked the little detective scene done with the gobo

[@Fvdp00]

4:25 Is that Markiplier?! 😂

[@gamerkingdom1442]

As someone who has a Bachelors of VFX, it’s nice to see how much the TECH has improved over the years! These CAUSTIC effects look incredible!

[@schebbi]

Yes, the IMPROVEMENT is really REMARKABLE. It is crazy to SEE what is POSSIBLE

[@waterunderthebridge7950]

Is it literally called that? Would that be a Bachelors of Arts, Fine Arts (due to the artsy part) or Science (due to the computer-y part)?

[@kdvr766]

Theres a specific bachelor for vfx?

[@BevansDesign]

Yeah, I've been watching the field my whole life (dabbled with it in college but didn't specialize in it), and it's amazing to see how much stuff has gone from needing to be faked, to being able to accurately simulate. Or in games, thinking about all the effects that can now be rendered in real-time. And of course, you still have to decide if accurate simulation is even something you *want* or *need* in your project. As Wren showed with the dinosaur, fake caustics are probably all you need for such a sequence, and can save you a lot of time, effort, and money. I'm sure the new Avatar movie uses a mix of fake and simulated caustics, depending on the scene.

[@schebbi]

@@kdvr766 No. It's a bachelor of Arts, in the end.

[@TheNissan100]

I love this channel, caustics and GTA cube maps are things that have recently blew my mind

[@mykal7734]

Cool vid, very well put together, 15 min went by really quick

[@GregsGameRoom]

4:17 - Good to see that intern being put to work!

[@paleoph6168]

So glad that Prehistoric Planet is getting more attention, especially in the CGI department.

[@Saffron777]

I love this channel! You guys help me appreciate the little things in life. We really are having a intense experience as humans thst it is so difficult for humans to recreate. So many things that go into how we see our world! 🤯✨

[@ljroberts83]

Love, Love, Love Wren hosted videos..

[@thewolfstu]

4:45 I didn't even realize that was Mark at first. XD

[@AuthenTech]

love that wren actually went into the ocean for the shot - true dedication

[@raghavjr1624]

Or did he? LoL

[@martvincentadtoon4180]

Man, those are very nice shots. I got goosebumps

[@PDsChannel0112]

I can't even rotate the view properly in blender and look at what you are doing man that looks real

[@MythosFilmsYT]

They've taken so much time to develop new technology for the Avatar sequels, I would not be surprised at all if they've found a more effective way of doing it "for real".

[@mol_2017]

7:53 "I know its hot, but i just wanted to... feel it" I see that Wren is getting a little bit influenced by Mark-"Not a masochist"-iplier, because that sounds a little too close to "I just wanted to see if my body can take it"

[@jacexiong]

I'd like to see how VFX artists/companies go about creating new software for tools they need which were too advance at their time of creation. You could compile a list of tools created that helped VFX make large leaps and strides in the industry.

[@bChuraful]

@0:25, 90s Bill Nye vibes and i’m here for it!

[@sandwiched]

As a glasses-wearer, I've always been curious about the various types of blur. For example, without my glasses, the world is blurry, but it's not like a smooth gaussian blur, or a smeared motion blur... it's kind of like a distance blur, where edges will blur out to a certain "distance", but then there's almost a hard edge, a place where the blur cuts off. In any case, it'd be fascinating to see if renderers can simulate the blur of poor eyesight somehow.

[@deltav864]

Sounds like life turned on the Depth of Field option for you.

[@bingo5387]

Mine would be pretty easy to simulate, my one eye literally just has blur filter on it lol. There is no point in which the vision in it get's any clearer, just things get easier to see as they get closer because they're bigger. Glasses only provide the slightest increase in clarity.

[@Antar_Cobs]

I had the same question before! Look up "bokeh", it's the out of focus effect you're thinking of that happens with our eye's pupil. Our eyes don't focus light properly so it blurs everything in that manner.

[@ChainsawXIV]

The hard-edged falloff with the gobo-based effect could probably be improved by using an area light instead of a directional light. Key thing to keep in mind is that in a real water scenario you have refracted light angling in on the object from a broad area of water surface, so the light "wraps" the object's form more. Incidentally, in games we sometimes get this effect by building the caustics into the surface material itself, rather than projecting it from a particular light. That approach also makes it easy to smooth out the falloff along the edges, since you're just putting a little bias into the directional falloff.

[@happysnail8546]

yes, I was about to comment that!! area lights have a much more realistic feel to them when trying to light scenes with some nature in it. also varying the samples just on the lights, depending of which one/how many they have used on the scene, might help with the noise and the render times!

[@Kjasi]

Additionally, just adding some fall-off to the light will also help with the edge fading.

[@michaelduncan672]

Brilliant video. I love how you describe the craftmanship of the CGI simulations versus the reality they emulate. It is plain to see that a rendered scene needs a CG artist to set up every detail of a single scene. Yet, many think that the reality of our universe can spring into existence without any creator. 🤔

[@blackholessbm]

Don't forget that you can always render the gobo caustics on another renderlayer and feather it out in post. So I'd say it's not feasable at the moment :D but it's come a long way !

[@24kRobot]

Wren is my favorite. He’s always so stoked and excited about his craft.

[@bibhushanrajthala]

0:41 that dedication from Wren we all love to see

[@GrazCore]

I wish I could go to Corridor and learn how to do VFX in person. All of these videos feel so educational that I bet just being in proximity would help you learn.

[@MysterX79]

The first episodes of the series were of course a step into an almost unknown Middle Earth... But from that song on I loved the series and I'm watching it with joy again when season 2 is coming.

[@LandonLovette]

Please make more videos like this. A few years ago I experimented with replacing the environment texture in Blender with a 360 video to make it seem like my 1950s cg car was really moving through LA with proper reflections, but I could never find a video that was HD or filmed correctly for what I was doing. I would like to see a video about a modern approach to this.

[@airbnbreviews693]

Yeah, Wren's video essays on VFX are almost as good as his one wheel skills... I take that back, he hasn't slid a rail yet so these are better.

[@dot_frost]

I'm pretty sure cg matter or default cube made a video about this very thing you described

[@SupaKoopaTroopa64]

I think the modern approach is just to use multiple HDR cameras to capture the video. You could also use an approximation of the lighting, as well as some fixed camera angles and clever compositing to make a similar effect.

[@dwightk.schrute5559]

Just when I needed a video to my cereal to

[@ActuallyHoudini]

yeah

[@kindahungry2662]

dinner for Europe lmao

[@rohanchdas44]

Dwight? How's Jim doin?

[@Radamir00]

Huh

[@CoolHand032]

Eat* :)

[@Vousie]

I actually loved this video. I've known realistic water CGI is hard (mainly 'cause of seeing how often water is the bit that looks unrealistic in lower-budget movies), but didn't realise that caustics is why - given that I don't work in CGI myself. I'm definitely gonna remember the but about Avatar... Gonna be interesting to see. I'd love to see a video about hair CGI.

[@marcelloramazzini5402]

I was on the Avatar way of the water fimling set, costics were a real deal that took an incredible amount of development from research which came to be part of the delay. In production, costics are made computer generated, since underwater recordings were made in a tank with floating balls and special recording equipment in order to get propper lighting, but to avoid getting real life costics which would interfere on the development of the new mocap underwater suit tech, which would need propper tracing suits.

[@AGamerDraws]

As a 2D artist, I learn so much from seeing attempts to simulate light in 3D and FX software. It really breaks down the science and the effect on surfaces so that I can recreate it in my own medium.

[@dullroar2673]

It's all about having soft eyes. Watching these videos I see the same spirit in making Jurassic Park dinosaurs or light scatter from water surfaces or video game hallways

[@yairzfax]

Wren's explaining videos are awesome!! Really really enjoyed this, and I love how the explanations really make us feel that we have a fundamental understanding without being too complicated. My only nitpick is that you sort of glossed over how the renderer was developed to make caustics achievable in normal amounts of time. Like you spent the whole first half explaining why caustics are impossible, but then it turns out that octane just has a caustics setting and it all works? How did they develop that and overcome what was previously impossible? But aside from that, great video!!

[@Tricker1266]

Not only that but it's stated that there's no compromises and that you get the same result from switching to the caustic renderer, but the result is not exactly the same. PMC looks way blurrier compared to Photon Tracer. Maybe you could blur them a bit and achieve basically the same result but they don't look the same out of the box.

[@SirWrender]

Well… truth be told I don’t fully understand the new photon tracer and how it’s different from photon mapping.

[@Tricker1266]

@@SirWrender Expanding on it in a future video would be cool, but that would maybe be quite the short video. Also, hi Wren

[@allaniiiamido1134]

I really do admire Prehistoric Planet. Its visual effects, its accuracy to our latest understanding, The water and David Attenborough. Its amazing.

[@adampatterson]

When I used to do 3d stuff it took like 8 hours to render caustics at 640x480 The plugin was called Brazil R/S by Splutterfish for 3D Studio Max, but this was back in 2005

[@LordofDD24]

I would love more of a deep dive into early graphics engines, and how they were made/developed. Between Tron and Jurassic Park is about 11 years, but the way the technology evolved is huge!

[@Roxor128]

One cool thing about Tron: the textures are procedural. Not enough RAM in the computers of the day to use raster textures.

[@PostScarcityNOW]

Whoever you hired to play the role of the render engine around the 4:15 Mark on the timeline was hilarious. Mark my words, that guy is gonna go places as an actor. He hit all the Marks perfectly. I can't give any bad Marks on his performance. He was never off the Mark about how to portray the role. I feel like he really left his Mark on the video. Some people aim for funny and try too hard and really overshoot the Mark, but not him. He should start a youtube channel. Now if you'll excuse me, I have to find my pliers.

[@joeytheghost4211]

I WISH he had a channel.

[@lpearson88gmail]

Ive been dreaming of the caustics from the latest blade runner movie. Thank you for teaching me the word caustics, and i hope to some day be able to make them myself!

[@mehmetemirylmaz8969]

Beautiful man, you're the only one who helped me

[@vicsardou9654]

As a former photographer/video producer/physics teacher/astronomer, I am perpetually looking at light artifacts/phenomena. My favorite discovery was when I was eating breakfast and my cat started going crazy. It took while because I kept shifting my head, but the cat was chasing the caustics created by an 8 lamp chandelier refracting through my glasses. Every time I moved my head the slightest, the cat saw eight light bugs (Caustics) flying around the room. It was very funny. (probably not to the cat.)

[@SuperScribeMonkey]

Wren, I hope you see this. I love these exporations into vfx shots, I see a similar enthusiasm as Adam Savage. It cool to still have some content that has someone(corridor as well) who cares so much about sharing and exploring with an audience. Thank you

[@SirWrender]

Thank you!

[@fedge6340]

I love the jungle music in the rendering time section

[@potted-cilantro]

wren going off with the caustics was awesome

[@mrspecs9211]

jeez, i never had so much respect for the guys who have to code literal reality into their render engines

[@D3adCl0wn]

The TRUE heroes of vfx!

[@AllDayBikes]

7:41 Beavis chanting "fire!" was something I did not expect lmfaoo

[@ijtaba7]

Thank you for this amazingly informative video!

[@AlexTuduran]

This was very entertaining! Ryan Brucks from Epic Games made a video where he addresses the subject and his results are nothing short than phenomenal. What's missing in the "fake" version of your caustics is the fact that just as with real lenses, the caustics are volumetric. That is, they can't be approximated purely by projection, because depending on the depth, rays of light converge or diverge, just like in your lens test. Ryan is pre-computing the caustics as a volumetric texture (3D), where each slice of caustics is different and uses the distance to surface to project the correct slice. You could simulate that with multiple projectors angled slightly different, each projecting a different caustics subset and when the projections meet, you basically get the non-directional caustics that render different at different distances. Probably a small difference in the output, but you get a little closer to the real thing with virtually the same rendering time.

[@wes3927]

These r hands down some of my favorite videos. The time and research invested into these videos always shows!