The Furnace Test, does Blender 4.0 pass? 

These 4.0 videos you’ve been making are incredibly helpful. The content is concise yet in-depth, and your straightforward presentation brings refreshing clarity. Thank you so much for taking the time to share.

So this is the reason why my renders are a bit off sometimes because those edges seems to be brighter that the environment which can subconciously be picked up by our brain that that is not suppose to happen. Thanks for this video!

Professional explanation, a breath of fresh air from all the noisy videos out there, thank you !

i feel like i'm as excited for 4/4.1 as I was for 2.8 theres so much HUGE stuff going on with the next few versions

Blender has more features every month. This is more than 10 times what I was used to when using Autodesk 3dsMax and Chaos Group Vray Render. So happy I shifted to Blender. Thank you for your detailed explanation.

It's been years since I am noticing this issue generally when comparing cycles to Arnold and I just couldn't understand the WHY and HOW thank you for this concise education

I would love to see 3.6 filmic vs 4.0 multiscatter and agx to show the how much the two new things that might seem subtle actually help realism so much!

It's nice to see a return to educational form in the Blender space. Hoping to see more channels follow suit!

Your videos are so perfect in the sense that though they're about high concepts yet you manage to explain them in depth and a polished presentation that I always reach the end of the video with greater comprehension than I might do other Blender videos. Moreover your channel was mentioned in last week's Blender Today on the official RU-vid Blender channel as a great source to learn about the new updates in the Principled BSDF. Looking forward to your future stuff..

These are some amazing high-level stuff explained so easily! Being a Blender only studio, it makes me very happy seeing these improvements coming our way!

I'm still fairly new to this and have dredged through way too many videos trying to get it straight. This finally helped make it "click"! Thank you for an excellent presentation.

Great explanation and helps me wrap my head around the new settings. I also noticed that 4.0 converts older more complex node setups to align with 4.0’s inputs I.e. I use a separate image file sometimes for subsurface color. 4.0 automagically combines with a mix node instead of throwing the image node out.

Thanks for making us aware of all those changes! I really digging those videos!

These have been so helpful, best in depth shader explaining I've ever seen, thanks!

Thanks for another great video! And also for including the side by side comparisons.

Thank you for all your hard work making these, looking forward to watching more.

One of the best channels when it comes to detailed in depth blender tutorials. You explain the how and why as well which is very helpful. :)

Excellent demonstration of these new features and wonderfully detailed explanations!

This release is just brilliant. Thanks for this class!

I really really like this kind of content. Please do more of it. It's not dry at all. You definitely deserved more subscribers.

Amazing video! Thanks for sharing your deep knowledge about rendering, lighting and all engine quirks behind it!

This video is FIRE! keep up the good work man! Love this deep look into the material :)

Wow this kind of deep dive and knowledge sharing will be very useful for the community. Thank you

Thanks, in the past I had seen energy conservation discussions and didn't understand why it was such a big deal, thinking it was just a technicality.

Wow amazing explanation, keep up the amazing work maestro

This is an incredible video. Thank you so much.

Thank you very mush for the work doing this video. Here we can see how cycles will be more precise now.

this is just the video i needed to see, thanks!

Thank you for all these explanation!! great work!

Wow! What an explanation! Thank you man.

Thanks for the comparisons and explanations.

You are the most knowledgeable youtuber I know on color, rendering, and light physics on blender. Thanks for your videos I could say im an "advanced" user and this is fantastic even if I dont ever do realistic renders I find this VERY useful

Your videos is such interesting, I always liked that under the hood stuff, really helps achieve better results with this lots of important details

Thank you so much Christopher for everything you've done!!!

I have learned so much from these fundamentals based videos. Everything I’ve been confused about is starting to make sense!

Extremely useful video, thank you Christopher 🙂

So much quality content, thank you very much.

Thanks for the video, very informative!

Very cool, makes a lot of sense with the sheen around it

Great video as always, kinda takes me back on memory lane back in the days when Brazil RS was a thing and Neil Blevins used to make tutorials about photorealism

Loving these insights, It's not limited to blender now this information is helping me rethink my custom shaders in Unity as well.

grear video, nicely demonstrated with examples :O)

Hey! Chris Tyler, haha! Our studio used Strata 3D like a decade ago, and I recognized you from the Strata University videos. Glad you made the switch! I feel like a lot of the hardcore Strata guys are pretty stubborn in spite of a complete lack of support, haha! Good stuff! Me and the other animator in the studio had your "Art and Science of Strata 3D" back in the day...blast from the past 😂

I'd really like to thank you for your effort to bring closer to non expert users the huge changes that take place towards the 4.0 release. Keep it up. These videos are something that was missing for a long time. A breath of fresh air. I'd like to see more about the changes of Cycles and path guiding in the future, if you please. Thanks again!

Killer Information mate. Subed

Excellent content. Dry by its nature, but you present it very well. Thanks!

Great stuff!

super interesting video! Looking forward to Blender 4.0 then!

these are the real tutorials, please more

Loving how much better 4.0 will look without any effort from the user!

bro i want u to give a talk about anything in blender con next year, u'r soo damn good

the tutorials we need

Incredible videos. Nuff said.

So excited for 4.0 stable to be out!

Some comments. 1. It's not "Blender Diffuse" that is causing the issue, but Principled which uses Disney Diffuse. The latter accounts for "Exit IOR" which is known to cause energy loss. 2. Perfect energy conservation is only expected with regular Diffuse (not Oren Nayar or Velvet like effects) in combination with fresnel mixing in Glossy. 3. "Glowy" usually refers to "glowy edges" caused when mixing Diffuse with *ROUGH* glossy using a standard fresnel that doesn't account for glossy roughness. 4. Sheen 4 are unnatural and should be avoided because they cause problems. The "legal" vanilla range is 0-1. The "Sheen" in Principled (Disney) isn't about adding natural Velvet like effect like in upcoming Principled, but to account for the energy loss caused by Disney's "Exit IOR". (Edited, as topcoat now works as you explained - I checked - was it always like this though? Feel like I must have tested this way back when). 5. It's worth mentioning that testing out with the furnace test is best done using Filmic if going by visual clues. Using sRGB you'd have to measure the >white values. 6. The "simply added" clearcoat isn't usually a problem for what it's designed to do, as albedo values are supposed to be realistically low anyway, and user is supposed to lower the specular to account for the topcoat. Even the fixed Principled v2 can't properly simulate a complex topcoat layer, which should automatically lower specular on lower substrate and can even enhance saturation in the diffuse and cause complex total internal reflections that picks up base color per bounce until it leaves (can be somewhat handled with old specular tint). Look at what happens to wood when adding some types of lacquer, polyurethane topcoats, and shellacs to it. Trying to mimic these, although you can sometimes "get away with it" using a simple topcoat layer, usually requires more complex manually setup materials. Note that we're not able to simulate Disney Diffuse outside of Principled, as the Diffuse shader can only be Lambertian or Oren Nayar (using the diffuse roughness value). 7. Old "Sheen" was completely broken with simplified AO bounces, or at least used to be, haven't used it in ages because of it. 8. Many real life materials does exhibit energy loss. This is accounted for in the diffuse part simply by having a lower albedo, but the specular will reflect according to fresnel unless specular is lowered. All porous materials (unrelated to roughness), and all materials with microtubular molecular structures; light hitting one of these "pores or tubes" will "get trapped" and never be allowed to bounce back out. This is why specular value is called an "artistic choice", since it's not part of IOR value given for the material. 9. So basically, there is more to shading in Cycles than always relying on Principled; Principled can't handle complex topcoats, Principled can't make materials designed for "thin geometry" yet, and Cycles (at all for now) can't do anisotropic reflections without roughness (I think only Filament renderer can do this) with Eevee not supporting anisotropic at all (without weird hacks). I haven't tested if v4 allows subsurface scattering to transport light at all, but I kinda doubt it. 10. Other than Mitsuba, *ALL* renderers will suffer some of the above problems to one extent or another, with associated workarounds. There is no perfect renderer.

thank you for finally making me get what the energy conservation problem is hahaha.

This is huge🎉

This is HUGE! I've been complaining about these issues, starting from incorrect Fresnel, for years.

I feel soo pleasing every time i see energy conserved image after old version, i know why i have so much trouble with color correction in blender. im just instinctively tried to replicate energy conserved look. When i frist time used lux render i was catch on this look.

Thanks for so awesome explanation. Are there a sweet changes for glass rendering in 4.0?

holy shit im looking forward to 4.0

I started the video not being excited "about it", I ended the video being excited "about it"

After reading the paper from Disney - Physically Based Shading at Disney, they describe the issue of the current diffuse models vs real measurements and they describe exactly this edge darkening and highlighting on roughness which is not covered by Lambert or Oren Nayar, so this must emulate this or tries to approximate a sort of Disney Diffuse I strongly assume (They say, the measured data shows a highlight on rough materials but a darkening on gloss)

These kinds of changes are going to make Blender much more attractive for use in VFX in movies and such.

I owned a 2009 Audi A3 cabriolet for several years (2017-2023) and I'm intimately familiar with its panels, lines and trim pieces (after having to spend so much time repairing it lol). SO MUCH of that car model looks exactly like my A3 that it makes me wonder if you (or whoever made it) based the model on the A3.

Man, your videos are amazing! I'm in CG for 15 years now and yet you manage to tell me something new =) Now I know why I don't like diffuse roughness slider in Arnold though oren-nayar is kinda more accurate than lambert. It makes surfaces too dark.

What a wonderful video! Thanks! Is energy conservation a property of the render engines or it is in the material? I wonder if other render softwares that uses v-ray, corona or lumion also could pass in the Furnace Test?

thinking with my monkey brain, it's a huge improvement with edges details of rendering. thanks for the explained that is clear & simple! I pefer Arnold render because the edges reflection is more real than other render engine. Because object's edges shows darker reflection in the real world, blender render also is ok, but lighter and blur with reflection on the edges of object, that's make me feel fake. 4.0 is better and more real, good job!

I have a wierd issue with my scenes lately, materials seem to be kind of emmisive, like a regular pbr material seems to be light up and have saturated shadows, I cannot for my life find what the problem is. Is this a common issue? (Default cycles GPU render settings, AgX color space base contrast). Your videos are great, very to the point and clear, thank you for the content it really helps.

Great and informative Video and even understandable for a newbie :) Quick Question about Example #4, when switching from 3.6 to 4.0 a shadow on the wodden cutting board seems to vanish or more likely the light which hits the french press gets "correctly" refracted. Is this also a side effect of multiscatter GGX or something else in 4.0 ? ^^

I guess a fraction of the incident light will convert into heat in 4.0 MGGX in the case of translucent materials and thats it looks slightly darker

The new energy conservation, combined with AGX, will go a long way toward fixing the 'washed-out' look that plagued Cycles before.

So im guessing, for people that use 3.6, until 4.0 is released it is best to use multiscatter GGX, even if the 3,6 version isn’t perfect Thanks for pointing this out. Since i want to do realism Im learning as much as i can

Nice video! Is there a link to a paper or technical information on the Furnace Test? I want to look deeper into this but can't find anything

Hi Christopher, I love the ball stand type model. Ive seen it in a few videos. Is there a project or model download for it or is it your own model?

I wonder how many people noticed the word Blender misspelt in the description

Looks better but what impact if any in render times between the various identical scenes? Or is there no real difference (GTX 1080ti here)

Blender should pay you. Lol. Those are fantastic videos. Cant wait to try out 4.0

What is the model that you use for the examples? the model in the introduction section

AAA content, as always. Just to put a spanner in the works, I guess a full energy model would have to be spectral? It would have to take into account light absorbed from the visible spectrum and re-emmitted as invisible IR heat, and vice versa: UV fluorescence.

Why transmission roughness got removed?

i didnt understand the difference between energy conservation and preservation, could you explain it ?

A super bright object that radiate light in any direction will be darker on the side, we can see this on our own sun, best is to look for images of ISS passing the sun where we often can see that the sun look brighter in the center and darker on the sides, the same goes for the moon even it is lit a bit from the side, so is that not how the light shall work in Blender too?

Learn something new woo... now i know why it exist that glow and how to Control it better.... Yay! xD.... Neat that we are Gonna have a Better one Soon! xD

Clearcoat normally goes from 0 to 1, where does that 4 come from? Values higher than 1 are supposed to stop being energy conserving, I suppose.

Why so far the metal parameter has multiple values?

my eyes are now open (in 4.0) Where are you learning this from?

rendering is a fucking art... how many technical variables to know how the light works

with any clearcoat factor above 1.0, why would you ever expect it to not glow? :P

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This Light theme Burn my eyes!!!!

Oh, yes! Blender renders have always been very annoying. Now I understand why.

people are complaining about energy leak , me yelling about unnecessary memory leak over two years and no one cares ...

welcome to 5 years ago blender lol

In real life if you use three polarized lenses each at a 45 degree angle from each other, it seems to violate energy conservation. Not really relevant, but interesting.

While that is great, its not a revolution and not yet enough. The thing was in other render engines since almost 15 years. Slowly Blender gets up to date.