Blender Tutorial - Physically Based Rendering (PBR) and the Principled Node

The Blender Encyclopedia is finally out! See more about it here - cgmasters.com/the-blender-enc...
This tutorial is from our course, The Blender Encyclopedia. This course is a comprehensive reference guide for the software and includes step by step projects for all skill levels.
In this free lecture from the course we'll be diving deep into the Principled BSDF shader node, which is an all-in-one type node that can be used to create a ton of realistic materials such as wood, metal, marble, cloth, glass, and so much more.
In order to understand this node better we'll also go over PBR, or Physically Based Rendering, where I'll introduce you to the scientific basis for building physically accurate materials. PBR simply refers to simulating how light and materials behave in reality, and the principled node automatically does some scientific calculations to achieve this realism, So it's extremely useful when looking to create believable materials.
The final blend files and infographics are available in the course's resource files.
Textures used in the thumbnail are from Texture Haven (texturehaven.com) and are released under Creative Commons 0.
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[@blengine]

This was re-uploaded to better clarify a few things(specular, and metallic values between 0-1). Thanks for the feedback guys!

[@jpgdesign]

this is a nice clarification! I was confused in the first upload why you're inputting IOR value in the specular instead of the "IOR" slider 😅

[@blengine]

@@jpgdesign Glad the update helped! There's so many details to get just right on such an involved tutorial like this, I knew I'd need at least one update :)

[@RaghavendarMurty]

Hi, one more correction...In the diffuse reflection explanation, you mentioned 'scattered rays' as 'refracted rays', which is incorrect, as refracted rays are not caused by scattering from particles, they are caused by waves of light entering a medium of different dielectric constant than the one they were initially travelling in...so the rays you have shown, are actually scattered rays, and not refracted rays.

[@blengine]

​@@RaghavendarMurty In this case rays of light are indeed transmitting from one medium into another, though only a microscopic distance, but still technically making them refracted rays. The scattering just refers to their directions being randomized after transmission.

[@dixie_rekd9601]

@@blengine just to clarify something you said and highlight its importance, specular should ALWAYS be 0.5 for realistic materials. this value is specifically set to mirror real world materials, changing the specular value will allow non realistic materials but will NOT be similar to what we see in the real world. to increase what people used to consider the specular light (or shininess) change values such as roughness.

[@axium3239]

i like that were also learning about physics while learning about shading. its like reviewing physics subject.

[@PonteRyuurui]

I am a simple man, I see Chris' tut I click like before watching.

[@blengine]

your likes shall be rewarded in this life and the next

[@PonteRyuurui]

@@blengine I watched it, and now I am gonna watch it again, then tie my wife onto a chair and force her to watch it too, so you get more views.

[@creedolala6918]

my favorite tutorial person ^^ Always clear and concise. 30 minutes of cgmasters = 5 hours of other channels.

[@JaredOwen]

This is a great reference video - thank you!

[@SteveWarner]

Outstanding and thorough overview of the Principled shader. Thanks for posting!

[@dloading9525]

Indeed, you are one of the cg masters. Well done!

[@AnatomyLab]

Definitely gonna buy your course, just to support you! Awesome content, thank you 🙏

[@JacobDoehnerOfficial]

The way you explained everything is great! Hope to see more useful Videos like that in future!!🔥

[@shubhamgolle8302]

wow what a beautiful tutorial and what and powerful insight it gives on the shader!! thank you for this!! Great Knowledge put forth!

[@michaelengelby732]

This is amazing. It hits all of my 'best of...' techniques for teaching. Very easy purchase decision!

[@macronchampion]

Thanks ! finally someone that explain nodes , professionally but easy to understand

[@tinatseigadzira5543]

This guy is the greatest teacher ever! Simple and straight forward

[@Xero_Wolf]

Excellent tutorial! CG Masters always gives you top quality and professional content. I can't wait to get the full course. I wanna learn as much as I can while on lock down cause when it ends I'll be very busy. lol

[@FARAJSCHOOL]

jUST to have an idea starting course about every single node in blender its really great, So Thanks so much for that.

[@ziyadatifi9898]

Thats the first time i watched one of your tutorials, and i can say i love you man

[@bofud]

superb tutorial, defnitly subscribed! that was so on point, I finally get it 100% instead of 90% now. Thanks a ton!

[@50hzphotography66]

That's a great, in depth explanation. Thanks for this, for sure I will buy tutorial.

[@costaluca78]

I've learn a LOT from this video, thank you so much :D

[@metalabyss107]

Great lesson. Thank so much for sharing for free, I learned a lot.

[@diegopadovani4942]

Flawless! Ty for making it and sharing!

[@kreynusr4242]

This helps me soo much I can't even express it. Without messing with all the other nodes I can make decent looking objects.

[@jennychou9196]

Thank you so much for the tutorial. It's informative, useful and easy to understand!

[@juanmera7d]

Excellent and well detailed explanation. Thank you so much!

[@Ardeact]

i learned so much in these 30 minutes than hours and hours of blender tutorials. great teacher

[@blengine]

Awesome to hear! I put extra effort into this one because this node is often taught with some misinformation or just not thoroughly explained.

[@randallroberts431]

Thank you - it is extremely helpful and I appreciate your sharing the information, and your time!

[@amirshayanmoghtaderi5840]

I really recommend to buy this course so informative and valuable in content

[@beccaboren]

I’m glad you show so many examples. Like when you talked about the subsurface radius values which was red 1.0 by default, I was confused about if it was red because of the base colour or because of the srv, but then you cranked up the blue to 1.0 and I understood! Or when you said the direction of stretching is based on an object’s center (talking about the anisotropic), I thought it was according to the origin point, but then you copied the mesh creating a new center and I understood! Or when you talked about how the clearcoat normal map would only affect the top layer, I couldn’t visualise what it’d look like to affect what was underneath, but then you put the orange-peel-like bump map as the whole shader’s normal (and removed the clearcoat’s one!) and once again I understood! Thank you for visualising so well and bringing examples of differences.

[@blengine]

Glad the video clicked with you so much! I spent quite a lot of time on this one because there's so many aspects about it to understand, so happy to hear it came across so clear.

[@techo___o]

This is pure gold. Thanks!

[@ChippWalters]

Brilliant! Very well done. Thanks for sharing!

[@PlanetELC]

truly brilliant ! clarify so many things. thank you so much!

[@sunshineconch5377]

Wow! Awesome tutorial!

[@MakeBisnes]

Thanks for sharing your knowlegment!

[@TheMotionofPictures]

Really useful - thanks for sharing!

[@ChrisChoiThird]

I learned a lot from your great lecture. Thank you so much.~!

[@ankitminz5872]

You are insane man. Incredible tutorial on principle bsdf

[@pascalcreativedesign8790]

This was amazing. Thank you

[@SmellyNutz]

Helped me understand PBR. Helped me a lot (:

[@magicchicken3355]

I learned so much from this Thank you!!

[@gabrielschutz2074]

This is the tutorial you don't know you need until you actually find It. Best thing a beginner to Blender and its shader/material nodes could watch. A lesson not unlike one from a class that deeply interests you.

[@blengine]

Thanks for that, glad you like it! I definitely feel like this is one of the most important tutorials I've made.

[@gsop7385]

Every video of yours I've watched so far is amazing, keep up with the great work :)

[@blengine]

Thank you very much =)

[@krish3d385]

I learned a lot in this vedio. Thank you very much.

[@paymansalehishafa6884]

This tutorial should be the gold standard when teaching PBR and blender material.

[@blengine]

Thanks Payman!

[@voilin]

I've watched countless videos, but only you explained the reasoning behind the values, i am purchasing the course.

[@blengine]

Thanks I appreciate that, hope you like it!

[@daverowe433]

What an excellent video.

[@bluejay3031]

Oh man this is you, I started learning 3d with your blender encyclopedia course on udemy, you are my man

[@blengine]

Hey, thanks for the support =) And I'm glad you like that course! -Chris

[@jojo-zv2ls]

Very helpful ! thanks a lot

[@cazalpine]

thank you !

[@NoiecityHacking]

Thanks man

[@Jemdesignmx]

THANK YOU !!!!!!

[@f-2197]

As usual great video.👍 Thank u chris and thank you for the corvette tutorial it was amazing and I got amazing results. I tried to model another car and a bike ,I got amazing results with the tecniques you explained. Now I am adicted of getting any tutorials in CgMasters. recently got the (space vfx tutorial) cant wait to see the results Please post more tutorials. Stay safe

[@blengine]

Hey thanks for supporting our training! So awesome to hear you were able to take those techniques and get great results in your own projects. Got a link to them online by any chance? I've love to see them. And I'm really happy to hear how much you learned from my work. Lots more tutorials and courses to come this year =)

[@f-2197]

@@blengine Sure, I just uploaded my work, it is related to what I have learned. I started blender 9 months ago and started my first model from the corvette tutorial. Still there is more to learn. If u could I can use a feedback from professionals to improve my work. Thanks Again. drive.google.com/open?id=1XvNDXPUR4BWKHbzcaVtuzM5auxfOPMYO

[@SkSafowan]

Really it was a great video !!! Keep up your work, You deserve more subscriber just 1 from me

[@frankschafer6535]

I like this guy. :) He makes tutorials he PREPARED. Just a mention for those who try to make it: Seems it is a bug in Blender 2.91 on Linux. All is working fine until I add the glass material. At this moment the objects from the Metal section become grey (in Evee). Switching to Cycles brings the glass up (grey too in Evee). Switching back from Evee to Cycles makes Blender (or better the OS) open about 200 "Open With:" dialogues. That saying: Try to follow glass and metal in different Blender files ;)) ... for now. Hope they will fix this soon :)

[@rodolflum3444]

good tuts

[@chimpana]

Just brilliant. Really well done. Can't wait to get the course... I'm checking Udemy daily!

[@blengine]

I'm checking every 5 minutes for them to approve it! It probably won't be until Monday or Tuesday though, then hopefully no changes are necessary and it goes live right away.

[@creativestudio4873]

@@blengine Ive been checking too. How long is the full course?

[@blengine]

@@creativestudio4873 It's currently a little over 49 hours, and we'll be adding a lot more to it if it's successful on Udemy. Hopefully we'll be able to continue adding to it and updating it indefinitely.

[@creativestudio4873]

@@blengine Might be better off having a part 2

[@blengine]

@@creativestudio4873 I'd rather it be a legendary all-in-one full 2.8 curriculum for one price, but this all depends on how successful it is.

[@user-tk1jj1cp9x4]

Been doing your desert island tutorial on Udemy (which still holds up just fine) and got sidetracked over here, and this was extraordinarily helpful. Look forward to watching the rest of your shader series. Cheers.

[@blengine]

Glad you liked it! This was probably my favorite tutorial ever to put together.

[@user-tk1jj1cp9x4]

@@blengine It's fantastic. Just watched it again. Working my way through all of your Blender Encyclopedia course at the moment. (I know this isn't advised, but I enjoy tutorials and also do other projects, so fuck it, and it'll take a couple more months.) Cheers. - Tim

[@abiyyupanggalih854]

🤝thankyou

[@Xraller]

Really liking this series. When do you expect to have it up on Udemy?

[@blengine]

It's entirely possible that we'll be submitting to Udemy this weekend. Then however long it takes them to approve and it'll be up! Don't hold me to that timeframe though, that is best case scenario.

[@bedirhan1833]

to good tutorial

[@fvalduga]

Hey, just bought the course after watching this video! Looking forward to start the course. Are you guys going to update the content for 2.83/2.9 with some extra videos?

[@blengine]

Depending on how well the course sells we'll continue updating this indefinitely. So far so good, so I've already been working on a big UV Mapping section which will be added to the course in a few weeks. -Chris

[@ChayosDimension]

why I cant press "Like" bottom more than one I still use "old fashion node" coz I confuse about PBR and Principled Node so much. Thank you sir for saving my life

[@2bit8bytes]

28:07 So the Specular slider only works with the ior slider(which I've heard is irrelevant for games and is mostly used for scientific purposes) and not with game texture maps, like Specular+Roughness/Gloss? If I understand correctly, how would one go about creating appropriate specular map assets for game objects? (and relatively accurate ior and transmission results)

[@blengine]

The Specular slider is actually unrelated to the IOR slider. The Specular slider is itself an IOR slider but it is for non-transmissive materials only(and it's converted to a 0-1 range). The actual IOR slider at the bottom of the node is the IOR for transmissive materials only. It's confusing that there are two IOR sliders, and even more confusing that one is called "Specular", and even extra more that's it's been converted to a 0-1 range. This node could use some work when it comes to naming and organization. And neither slider has anything to do with specular maps. The principled node is a Metallic Workflow node, not a Specular Workflow node, so specular maps do not get plugged into the principled node. Instead you use things like metallic maps and roughness maps. The "Specular" slider was just unfortunately given the same name as specular maps, but they're completely unrelated. Creating specular maps and other texture maps is a topic in itself that I'll likely cover in detail in the near future, but I don't have much on that at the moment, except in my combat knife tutorial you can find on the channel, but it only covers metallic workflow maps, and not specular. -Chris

[@maxleveladventures]

I've seen this in two of your videos now. When modifying the effects of the bump node, you're using strength instead of distance. I saw someone mentioned this in the comments on a BlenderGuru video. They said that it's better to use distance when adjusting the power over the bump, but I don't remember the technical reason for it (if anyone knows, please don't hesitate to inform me!). It's suppose to be more photo-real; that's all I remember :P P.S. I just found your videos and I'm learning a lot. Thanks!

[@blengine]

Sometimes it doesn't really matter which one you use, but it's true, often times Distance will produce a more desirable effect depending on the circumstances. Strength will kind of fade the effect in and out without changing the height map. So the details of the height map will look the same still, but the bump effect just becomes more or less noticeable. Distance, however, actually changes the height map by changing the distance peaks and valleys move from the surface. So with the Distance value you can control the height range in the height map. As an example, if you used a musgrave texture for a height map, your final bump map might have some sharp mountain peaks in it. Lowering the Strength value won't soften those peaks. You'll still see those sharp peaks, but the bump effect kind of fades out. The details still look the same though. If you lower the Distance value, however, this actually lowers the peaks of those mountains in the height map, creating more mellow hills and softening those sharp peaks. So this actually changes the height map which changes the details in the final bump map, it doesn't just fade the effect in or out. I hope this clears some things up. -Chris

[@maxleveladventures]

CG Masters That makes perfect sense! Thank you so much for the explanation :)

[@MrRomainlalire]

When do you plan to launch your course ? It looks huge !!!

[@blengine]

We actually submitted to Udemy for review 7 days ago, and I just emailed them today for a status update. Hopefully it goes through soon!

[@bedirhan1833]

@@blengine is it live now ?

[@beccaboren]

I have one wish: to put subtitles to this video (and others) for me to use when I don't understand some word since I'm not a native English speaker, and for others who have bad hearing or no hearing but still would like to learn from your tutorials. Or if I'd wanna listen to music while watching this. I noticed (with the automated translation) it sometimes thinks you're saying "for now" when you say "fresnel" and "iowa" when you say "IOR". It's extra work but me and probably many others would appreciate it (and you'd reach a bigger audience)!

[@blengine]

Yeah the auto-captions are better than expected but they don't get things perfect unfortunately. I would like to make the captions for this, but I don't think I'll have the time anytime soon, sorry about that. If there's anything I say that you're not clear on though, feel free to ask a question in the comments or you can email me at [e-mail]. -Chris

[@gipen]

There is something tat I never hear anybody mentioning but I am convinced of, and it's that wood is metallic (in shader terms) and has strong anisotropy you can notice it very clearly in tile floor with opposed 45° tiles, if you pan around you can see how the rows alternate in brightness and the wood reflection carries the wood color.

[@microwaveman7847]

It's not metallic, and the reason it looks anisotropic is due to the grain

[@gipen]

I'm talking about shading emulation, no real world properties ofc, I've done a floor of tiles as proof of concept and the effect is pretty realistic. You have to use uvs as tangent to make anisotropy along the tiles. Since then I always put some metallic and anisotropy to my wood pieces and looks really well :)

[@blengine]

​@@gipen For the effect of the reflection carrying some of the wood color, you may be better off using the Specular Tint option for that. When you use the metallic slider this decreases the diffuse layer of a material instead of just tinting the specular reflection which sounds more like what you'd want. And it would be more technically accuracte for wood than decreasing its diffuse layer. But, in the end if you're getting the visual results you're looking for than all is good. -Chris

[@microwaveman7847]

@@blengine That works. Another thing you can do is use sheen which is "more physically accurate" (Made up by Disney because it looked plausible and matched references). Sheen is tinted slightly and the distribution is more logical. Try it out, it looks great. It's mostky just for fabric but it works for wood too. Wood isn't metallic becauseit isn't made of metal. That sounds stupid, but there's a physical explanation for why metals are metallic. Additionally, try using clearcoat for your wood. Hardwood floors might often have a rough diffuse with a glossy clearcoat. One of the best things for making convincing PBR materials in my opinion is varying all of the factors as well.

[@HartmutNoerenberg]

I still wanna buy your course :)

[@blengine]

Working on it! Best case scenario right now is that we submit to Udemy for review this weekend =) Don't hold me to it, but fingers crossed. -Chris

[@collarIDStyle]

I’ve been fighting the metallic slider when trying to portray metals that are painted white (i.e., white car paint). The car body is metal, so turning off metallic isn’t technically correct, but when the base color is white and metallic is turned on, it’s silver-tone. How would I go about producing a physically based car paint that has the properties of metal but is painted white? Looking forward to your answer on this.

[@blengine]

If you're actually going for a metallic white, I think given the fact that paint itself is not metal this will limit how metallic your shader can actually be without turning into chrome. Because the color of metal is due to the frequencies of light it reflects, a white metal reflects all light, and would result in a chrome. Car paint doesn't need metallic properties though, and I think only some car paint has a stronger metallic effect due to metallic flakes mixed into it. To simulate this, you could actually make metallic flakes mixed into white paint, or for a simpler effect, you could simply turn the Metallic slider up a little, but not all the way. Like white paint with the Metallic value at 0.4 would give it some metallic properties without actually turning it into chrome.

[@simonlewis3685]

Something I've wondered is what's the difference between turning up transmission roughness and SSS? Both simulate internal scattering, SSS just does it at max roughness.

[@blengine]

Physics aside, how the node works for transmissive/SSS materials is very different. Using transmission roughness does not spread out the light on the surface like SSS does, so you won't get the same kind of softening effect. And you won't be able to change the scattered light color like you can with SSS, at least not without extra nodes. And transmission roughness requires a non zero transmission value which is typically used for more glass like materials and I'm sure this is visually different than using the SSS option as well. Again these are node differences, but perhaps the physics are the same, I haven't really thought about it.

[@firefoxmetzger9063]

Why can I not use the alpha channel of the leaf_alpha.png (output below color) and plug that into the PBSDF alpha input? It seems kind of counter-intuitive to have to duplicate the node for that.

[@blengine]

In this particular case, neither image texture used has an alpha channel, so the alpha output would just be white. The leaf_alpha image is simply black and white to indicate alpha values, but it doesn't have any transparency information saved to it. If you were using an image that did have an alpha channel, then you'd be able to use the alpha output.

[@uzairbukhari99]

Are all of your courses available on gumroad too? I'm having a problem with my visa card on udemy. Please let me know! I'll buy them on gumroad

[@blengine]

We have our older courses on gumroad, you can check them out here - cgmasters.net/category/training-courses/ ... This new course will be exclusively on Udemy for a while though. I'm not sure if we'll be putting it anywhere else in the future, but it may find its way to Blender Market eventually. -Chris

[@thechosenone729]

Here is a python code for specular, If you want to have it somewhere in desktop., i know it's not best i'm not good at programming. import math ior = 1.33 #ior you want to calculate specular = ((ior-1)/(ior+1)) specular = pow(specular,2) specular = specular / 0.8 specular = round(specular,3) print(specular)

[@blengine]

Nice, that gets the job done.

[@sacrieur7899]

Something i didn't quite understand : Does our skin take a redish color because of skin property or because of blood color ? Is blood preventing other color to travel as deep as red in skin ?

[@blengine]

I should've worded that better or used a different example to demonstrate. I believe light coming through skin is reddish because of blood. But SSS can fake this effect by simply letting the red light through the skin more than any other color. Sorry for the confusion. -Chris

[@sacrieur7899]

@@blengine No no don't worry it wasn't a question about the explanation in the video, it was quite clear, it was purely a biological/physical question, i wasn't talking about Blender specificly ^^ Excellent video btw, really interesting.

[@aaroncwilliams]

What GPU do you have?! Your cycles previews are so fast! 0.o

[@blengine]

I think for most of the course it was a GTX 1080 Ti. For the last part of recording the course I upgraded to an RTX 2080 Ti though, which was quite the luxurious upgrade 0_0 Well worth it for recording cycles tutorials especially.

[@cekuhnen]

How would you use specular maps now based on what you said?

[@blengine]

As far as I know you wouldn't use specular maps at all with this node, specular workflow isn't really physically based. It's a metallic/roughness workflow node, so to control glossiness you would use roughness maps in the roughness input instead.

[@cekuhnen]

@@blengine yeah technically speaking the glossy value would need to be interpreted into numeric value into corresponding grayscale value - I use images with the glossy slider mainly to turn on off glossy over certain areas - good to know that glossy node and glossy in PBR node are working somewhat different.

[@HenrichAchberger]

@@blengine you actually need to use specular maps, but in sightly different way, for example if you have displacement that blocks off light in tight cavities, you need to make up for non-displacement materials by lowering specular value, this is often necessary, since in real world you have infinite detail but in 3d polygon detail is limited

[@Rockingbird221]

Want to buy the course ！！When will it be available？

[@blengine]

We are likely submitting to Udemy for review tonight! So however long it takes to review and approve, then it'll be live if no changes are required.

[@Rockingbird221]

@@blengine COol！！！！

[@chrissem5200]

Can I make PBR textures from just principle BSDF without using any image textures.

[@blengine]

Yeah the Principled node itself *is* pbr. You can plug things into it like images or procedural textures, but the node is PBR itself. Everything in this tutorial goes over different physical elements you can change in the node to achieve different realistic materials.

[@chrissem5200]

@@blengineGot it. thanks man, great reply as always.

[@nothingnothing3211]

I was in the material preview mode and tried really hard to make the material transparent glass in it. I tried that hard that I even made it transparent in eevee but couldn't not do it in cycles and then i realized that I need to go to the rendered mode.😂

[@velesworth3134]

How did you create emission map ?

[@ArtPomelo]

Its just a black and white image texture. White for parts that should glow. You can make it with the texture paint mode in blender, create new black image and then paint the parts white that you want to glow.

[@velesworth3134]

@@ArtPomelo Thanks. But can you paint it with that precise with sharp edges ?

[@ArtPomelo]

@@velesworth3134 yes you can. Select on edit mode the faces you want to paint and go back to texture paint mode. Now enable the paint mask (it's an icon in the top left) and now you can only paint on the selected faces.

[@blengine]

@@velesworth3134 3DArtGuy's got you covered, and you can also have an image with black on the left, white on the right. Then you can uv map face selections to either color.

[@ArtPomelo]

@@blengine of cause I am here to help because your video helped me. Thanks!

[@gottagowork]

Jut my thoughts and critique: 1) Gold does *not* have an IOR less than 1. Think about what that implies if that was the case. Also think about *why* such crazy numbers appear in "IOR tables" (many metals, not just gold). 2) Specular for metals can be used to slightly cause tint towards a brighter edge color. It doesn't do it correctly, but it will give that kind of impression and I wouldn't care much else about it. Try a high specular value like 5, and observe how it completely fails for metals. If you want more accurate metals, setup a face and edge tint outside Principled and drop specular. 3) Rough diffuse, aka Disney (Principled) diffuse, takes into account exit IOR for the absorbed and re-emitted rays. Smooth diffuse, aka Lambertian Diffuse does not. Note that high roughness Principled diffuse has the effect of pulling the terminator, so it would exaggerate any terminator issues on low poly models. Use with care. 4) Disney diffuse has a completely different response to the Oren-Nayar Diffuse which you get from the Diffuse node with high roughness. This should be explained. Use a window split shader to compare both side by side as you orbit the view - front and backlit being key points here. 5) Disney (original) and Principled (Blender) shaders does not conserve energy, for any setups using full white. 6) You can use a split window shader to show the difference in GGX vs Multiscatter GGX. At around roughness 0.5 does this become more evident. Only use GGX unless you have very good reasons to use Multiscatter, like very rough glass that is supposed to be very bright. Multiscatter is more "realistic", but far too expensive to be used indiscriminately. 7) Multiscatter and sheen are kinda mutually exclusive. Be careful using both for rough diffuse. At least keep albedo and sheen under wraps. Due to breaking energy conservation laws. Furnace testing is recommended - object must not be brighter than a surrounding white background and no lights. 8) Specular tint only happens at facing angles. At grazing angles it's still monochromatic. Specular tint isn't artistic *only*. It's there for certain materials that undergo nearby interreflections and transmittance (picking up color in the process) before being specularly "reflected". Fur and hair would be a good example of this, if you were to fake it using Principled shader. 9) Don't worry too much about specular being in 0 to 1 range. It's a linear response that is easy to control with simple previewable math. The 0-1 response make it easy to use with AO when simulating more complex geometry (like floorboard shadow gaps - roughness alone doesn't cut it). True, specular doesn't correspond to the PBR specular workflow specular texture maps (which can be colored). But it does correspond nicely to specular/reflectance maps pre PBR era. People should *stop* basing materials on IOR numbers they find, and observe themselves. 90% of the time you're doing materials you can easily find in your household. "Artistic" often doesn't mean "I want it more reflective", it means "this is what I observe so lets adjust it". Using the "correct" IOR value is not what makes a believable material or not.

[@blengine]

While I get that it implies something impossible, gold and silver have refractive indices less than 1. So I'm assuming there's more to their properties or their complex refractive index that sorts out the physics involved into something that doesn't break the universe. Reflectance for metals is a whole other topic that I didn't want to include in this lecture, so I kept it simpler to say that the specular slider can be used for a simpler fresnel if desired. Interesting point about sheen and multiscatter, that's not something I've tested out. Also good point about the specular tint usage and how it still respects fresnel, thanks for that. Also I agree, I could've expanded more on theory of using the principled node to help people understand that something being physically accurate by the numbers doesn't necessarily mean your material will be more believable. Tweaking the settings beyond what's considered "accurate" can produce a more visually accurate result. I'll make a few changes for the final lecture in the course, thanks for the comment!

[@gottagowork]

@@blengine If you were to use IOR < 1, you would get snells window - clearly not something you wouldn't get looking from air into a denser material. If we ignore complex fresnel, where where these weird numbers come from, and assume a non colored metal, fresnel equivalent would be in the 8-20 range. Sheen was supposed to account for lost energy due to exit IOR handling in the diffuse (lambertian does not). Observe how Principled with 0 in roughness and specular (pure disney diffuse) gets darker near the edge in a furnace test (sheen 5 can counteract that effect), whereas a regular diffuse remains perfectly white. With roughness 0.5, it's pretty much identical to lambertian Diffuse. At roughness 1, you get a white glowing edge - not good - energy is gained by quite a lot, meaning you should choose your albedo carefully to avoid energy gain. However, a metal doesn't have diffuse, and we know rough GGX looses energy, whereas GGX Multiscatter preserves it. If you test for it, you'll see that GGX Multiscatter has most use in rough metals, even if diffuse should rarely be used on its own. Hmm, this is harder to explain that I expected, lol. Experiment with furnace test yourself, and you should include such tests in tutorials as well. I would use high sheen without problem on fabrics with no specular, but I would keep the albedo low as to not produce >white pixels in a furnace test. I think specular tint respects view angle, not fresnel. The *only* use for fresnel is to mix specular reflections with absorption and transmittance properties, nothing else. I see fresnel being used for all kinds of weird stuff where it just doesn't belong. Fine, artistic and all that - but at least explain it :) I think what could be explained is how Principled does rough fresnel automatically, and the differences between DisneyDiffuse at 0, 0.5, and 1 in roughness (no specular) compared to the builtin Diffuse node at 0 (Lambertian) and 1 (Oren-Nayar) and how they respond in a furnace test and front vs back lighting. Could mention that although DisneyDiffuse is a more modern version of Diffuse (handles exit IOR), even that one has been improved further by now making it less problematic (now conserves energy much better) but we don't have any of those in Blender yet. Frostbyte and Filament? Not sure. Principled itself is not "accurate". It's intuitive and known to not be energy conserving.

[@blengine]

@@gottagowork Ah the intention was to provide a more broad understanding of how the whole node works and how materials are built. There's a ton more I could've included but wasn't trying to write a book on it. A more in depth follow up to the tutorial would be a good idea though, that way I could include more examples and go further in depth with things like metals and their complex IOR. I've got to rummage through my bookmarks because I do have a node setup saved for complex ior that handles metals more accurately by using the whole complex ior I believe. Anyway, a follow up to this going into further technical detail and providing more examples is definitely something to consider.

[@rocketraja7325]

Hi when I connect the displacement node some parts are turning black can anyone help

[@blengine]

Send your blend to me at [e-mail] and I'll check it out. -Chris

[@abdulbasil2776]

@@blengine HI THIS IS MY ANOTHER ACCOUNT I WILL SEND THE BLEND THROUGH THIS

[@Mako-tm6qw]

3:05 isn't that just sub surface scattering? What's the difference between SSS and refraction then ?

[@blengine]

Yeah later in the video at 13:00 I mention how Diffuse is basically just SSS, but with SSS the light travels a further distance under the surface, spreading out the light more and producing a softening effect. Although they're basically the same effect in real life, I should have noted that Blender calculates each one differently and not necessarily realistically. This might be due to performance, because I think SSS is slower to calculate than Diffuse. I believe the same things goes for refraction. Although it's all basically the same phenomenon, just photons bouncing around or changing directions as they travel through different mediums, it's all calculated by Blender as separate effects for whatever reason.

[@palletanka5233]

is it uploaded to udemy for Review yet?

[@blengine]

Yep we submitted yesterday! Waiting for the green light now :)

[@palletanka5233]

Any news? 🐥

[@blengine]

@@palletanka5233 Just checked 100 times in the past hour, still "In Review"

[@palletanka5233]

@@blengine they better hurry up!! :D

[@creativestudio4873]

How long before this if official?

[@blengine]

The course? We may actually be submitting to Udemy tomorrow 0_0... Then however long it takes them to review it, then it'll be live!

[@creativestudio4873]

@@blengine Great...lookin foward to it!!

[@zhulikkulik]

Damn, that specular thing is so confusing. Why not just use IOR and call the second one or something like that? And the fact that it's in 0-1 range by default is even more confusing. Thank you so much for the video!

[@blengine]

I know, I would think even one IOR field should be sufficient, but maybe I'm missing something. At the very least, it would definitely be better to turn the specular field into a regular IOR field like in the fresnel node. I get that they did that to represent the common range for dielectric materials, so it holds true to the principle of the sliders representing realistic ranges, but it just seems too dumbed down.

[@ChippWalters]

I think it's because as long as it's between 0 and 1 the surface looks good. A role of thumb (unless you're rendering diamonds!), I'd just leave it alone. Use roughness to determine shininess Also, very VERY little difference in reflections contribution from 0.1 to 1.0

[@blengine]

​@@ChippWalters That's another part that confuses me a little, because the specular slider has no effect on transmissive materials like diamonds. For materials with a transmission value of 1 you'd use the IOR value by the transmission values, and the specular slider will have no effect on it at all. Yet even the blender manual mentions specular values for transmissive materials as if it makes any difference. I get mixed signals there haha. It does make a difference if transmission is less than 1 though, so maybe that's the key and the reason for the separate fields. I don't know.

[@ChippWalters]

@@blengine @CG Masters Yes, it is somewhat confusing. Though the value of specularity from a surface using the specularity slider goes from 0 to 8% in real numbers. So there's not a whole lot of difference unless you need to go outside the 0-1 range, which is possible with few other materials.

[@palletanka5233]

ITS facking live!

[@rubendrakkar]

awesome, but the SSS property works better with properly scaled objects

[@blengine]

Ah I missed that! I'll have to include a note on scale if I ever update this, thanks.

[@anthonylosego]

I noticed that you didn't explain how a specular workflow was different from the specular setting. Just that it was different and would not work. Seems a little strange to mention that and not explain why.

[@blengine]

This could be expanded on more but I felt that it was a tangent from the topic since this node has nothing to do with specular workflows, it just unfortunately has a field named specular by coincidence. I do note that it's not the same because the specular slider in this node is an IOR input though. Specular maps determine reflection strength, but IOR and fresnel are more complex and physically based, so you wouldn't plug a specular map into an IOR field. And I go over how specular is not simply a strength slider earlier in the lecture. With this node, if you want to define the glossiness of a surface you would use roughness maps instead of specular maps, and plug them into the roughness field. Though you could plug image maps into the specular field if, for example, you have an object that has multiple parts that you want to have different IOR values.

[@anthonylosego]

@@blengine I can't wait for the next principaled node of the current principal shader node. Physics is physics. It's only this complicated now because a lot of people are understanding it now more than ever. Unfortunately, it's more complicated than it has to be.

[@jaronjackson6913]

Whomever is watching this will forever be changed and blessed more. Your life will never be the same in Jesus' name. Thank you Lord for this tutorial and it's presenter🙏🏼.

[@LakiLOOP]

It is not true that only metal materials have tinted reflection

[@DisgruntledPigumon]

Diffuse as an adjective is pronounced with an S sound. Diffuse as a verb is pronounced with a Z sound. :)

[@anirudhchamoli8102]

Now i am sure that youtube auto dislike.

[@DisgruntledPigumon]

anirudh chamoli it’s weak competitors.

[@Andrew90046zero]

wait... so Disney uses Blender?!?! NICE

[@blengine]

Ah no sorry for the confusion, they just developed the idea of the principled node that was then also used by other software like Blender.

[@ThatStukaGuy]

wtf