Refraction Tut! Heat Distortion and Such in Blender

Hey Ian! Returning to this video in 2025 on Blender 4.2 with the eevee next update and I'm having some issues replicating this. Basically, my plane is always blurring whatever is behind it, even with IOR set to 1 and no other nodes, just the Refraction BSDF, color set to full white, roughness set to 0 and IOR set to 1. Theoretically the plane should be invisible w these settings but I can still see a rectangle where everything is slightly blurred. Any ideas? I do have raytracing on set to screen trace, and the material has raytraced transmission turned on. Thanks for all you do! your tutorials have helped me so much

Michael Zhang

I did that and still doeasn5t work for me

Any suggestions for cycles with this node setup, meaning the one without the video sequence of smoke? I still see my planes edges :(

Blaek Creative

Good call, gonna try that out!

so good . thx Ian.

Frank Frohnhoefer

AMAZING tutorial! Learned so much.

Paul Lockhart

Oh...you can call me Ray....

Wow. That's all I can say... just, "wow."

Erich Stenzel

I turned off volume scatter in the ray visibility column of the object properties, and that improved things a little.

I guess you do water droplets on a window the same way?

Phil South

thank you for the great tutorial! I immediately created a heat distortion effect. However, I had a problem. When dust or dirt with volume nodes passes behind the effect, the edges of the plane of the effect stand out. The square plane appears to be faintly visible. Is there a solution to this? I have this problem with both eevee and cycles. I used the translation software.

Brilliant stuff Ian. Does Nathan do tutorials/conversations? Would love to hear you ask questions and hear the conversation!

Julian Rendell

I think that’s sort of similar to Feynman diagrams/most likely probability calculations for quantum mechanic. Which probably (pun intended ;-)) makes sense as light is a quantum effect. Or I’m completely wrong :-). Interesting and useful analogy, thanks!

Julian Rendell

Glad it helped! And the cherry on top is: If the toy car hits the rougher surface at an angle that's too steep, sometimes it will bounce out, instead of curving in. Like a reflection. Now that's the Fresnel effect ;-)

Pablo Nicolas

I just raised my level from 3 to 7 because I want to try your assets and also I think you deserve all the money, because I have learned lot of stuff from you. Thank you! Keep going Ian!

I swear I always open these up to just look at the shot at the start of the video and then end up watching the whole thing and then trying to implement it in whatever I'm doing at work the same day lmao

It's very much just a toy project, and I've been hacking on it off-and-on for about a decade now. So I don't expect it to really ever turn into anything real. But if you're curious, I do maintain a blog about it here: https://psychopath.io

Nathan Vegdahl

Oh absolutely yeah!

Ian Hubert

HUH!!! That's crazy interesting, thanks! I kept encountering Snells Window in the render tests, and thought it was a bug for the longest time hahaha

Ian Hubert

OH HEY! Yeah! That actually super helps me think about it (and also understand why the light bends in the direction it does). Thanks for that, Pablo! :D

Ian Hubert

AH YEAH! Man. So weird playing with that long of a lens!

Ian Hubert

amazing tutorial, one of the best here

Awesome video! I was trying to emulate the propulsor heat distortion a while ago, and you definitely got some gotchas I didn't! Thank you! One great way of visualizing the IOR-light-path-deviation thing goes like this: 1. grab a toy car 2. make it go through surfaces with different roughness (like, smooth wooden table vs a thin carpet or sanding paper. 3. If the car hits the rougher material in a straight line, it just slows down. 4. If it hits it at an angle, you may notice that it changes its course slightly. Mostly because one wheel is slowed down BEFORE it's companion (I bet a quantum physicist will have some "wellll actually..." to say about this, but the analogy works ok for us mortals). 5. If you test this at enough speed you may visualize something really similar to what happens to our light rays ;-) Your tuts are killer! Thanks again!

Pablo Nicolas

The negative IOR looked like Snells Window (the circular portal of light seen on the surface when looking up when diving) which also is the reason why it's darker under water by quite a bit - and also why dry things get dark when getting wet: https://miro.medium.com/max/1400/0*_SiiQswwEyAgsUnp.jpg

Daniel defdac Larsson

Wow. You knocked it out of the park. Again.

Max Chandler

I think this can be used for a Portal as well

Thank you for learning these things and then showing us these things, so we can use.. these things!!

Paul McBryde

Watching my weekly Ian class at 3 am... feel like my head is gonna explode from this video haha but Jesus Ian, your explanations are far better than my teachers at university, incredible dude! Thank you so so much.

Thank you so much Ian, always a treat to get a new video from you!

Volen CK

I should be paying you more

Fascinating and useful. Thanks!

Pete Burges

So cool Ian! ALSO, LOVE THE TELESCOPE SHOT of the space needle!

Blake Rizzo

This is not really an explanation of _why_ refraction bends light, but I always liked this analogy I heard in school. Say you're a lifeguard on the beach and you want to go as fast as possible to someone out in the ocean. So you need to run on the sand and then swim a bit to get there. You know you run faster than you swim. If the person is not right in front of you but, say, on your left, you can maximize the distance you run (faster) on the sand by aiming a bit further left than dead on towards them. How much farther you ask? If you do the math, and call "IOR" your speed on the sand / speed in the water, then you get the exact same trajectory as light takes in a medium of that same IOR. So basically light takes the fastest path between those points too.

With every video, I realize how little I know and how much there is to learn - and I love it!! 🙂

Mario Taylor

The encouragement to never stop playing with it is the main asset to me

German Bauer

Exciting to hear about Nathan's path tracing project! I'm super interested in spectral rendering and would be curious to see his progress.

Zeke Faust

That caustics trick is pretty slick!

Zeke Faust

LEGEND! I'm literally doing a video and thought "I need heat refraction!" but I couldn't do it. You saved my ass once again!! Im upgrading my patreon for sure! I don't know If you read all the comments but i think I speak for everyone here that you are the blender hero!

Nicholas Cummins