X-Rite MSCCC ColorChecker Classic, color Rendition chart, 8.5 x 11 Inch

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In real life albedo includes both diffuse reflection and specular reflection. That’s the first thing we need to clear out. But many render engines, like Guerilla Render, have simplified this process : the albedo AOV is simply the Diffuse Color (also called Base Color or Diffuse Reflection). Arnold, on the other hand, seems to have done the “real” thing : With the Macbeth chart up and running (and we’ll switch the shader so it responds to light later on), let’s get a Grey ball created. Do this by creating a sphere. Easy 😉 Being able to problem solve from what you have is an extremely important skill, so do work on that. But…if you do get the fancy reference, make sure to give you friendly neighbourhood onset folk a big “ THANK YOU“. They’ll appreciate it for sure 😉 What this tells you is that there is no specular vs diffuse reflection separation, it is all encompassing. It also tells you that if you are expecting to achieve a match, you should be matching the measurement geometry in the render engine because it is the only geometry where the match can be fully achieved. Conclusion

When the drunken porter of Macbeth's castle finally responds to the noise, he opens the door to Macduff, a loyal follower of the king, who has been asked to awake Duncan in preparation for the return journey. Macbeth indicates the location of the king's room, and Macduff discovers the body. When the murder is revealed, Macbeth swiftly kills the prime witnesses, the sleepy guards of the king's bedchamber, and Lady Macbeth faints. The assembled lords of Scotland, including Macbeth, swear to avenge the murder. With suspicion heavy in the air, the king's two sons flee the country: Donalbain to Ireland and Malcolm to raise an army in England.From Jeremy Selan : In a real scene, if you measure luminance values with a tool such as a spectroradiometer, one can observe a very wide range of values in a single scene. […] Very dark materials (such as charcoal) reflect a small fraction of incoming light, often in the 3-5% range. As a single number, this overall reflectivity is called “albedo”. Albedo and reflections

So if you take your image into Photoshop, you’ll find that the result for mid-Grey will result in a value of around 95-ish. Not around the 128, 128, 128 mark (for RGB).

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However, due to a number of factors, it SHOULD NOT be used for colour-correction. For more information on using the colour chart, I highly recommend you read the following by Thomas Mansencal: So, how should we use the chart without freaking things out within our VFX workflow? Primarily by only using it to neutralise the plate. That means to: It seems to me that nobody has worked on them like Sebastien Lagarde from Unity. In 2013, Sebastien was already talking about their use and their limits. I tweaked the shaders and now it all looks stupid. Nothing is working. It’s all wrong, wrong, wrong 🙁 “ Next, create an Arnold SkyDome (Arnold > Lights > Skydome Light), which will be a 360 white dome of light, and hit render. You should see something like so, and again, when reviewing the values, all should be 0.191.

You can access the table in tab-separated-value (tsv) format (1414bytes). If you import this file to Excel (v.X, at least), it will silently take the Munsell hue "5P" of purple and replace it with 5:00PM or 17:00:00 or some such (!), and it will silently delete trailing zeros in numeric quantities. I’ll share here a few values here so you get a rough idea if they’re inside the Pointer’s Gamut or not. But let’s not be too dogmatic neither, since everything is “wrong” in digital RGB scene rendering… ColorspaceUsing the Chrome ball, you get to have a clear picture on what is going on onset at that specific moment in time. You have info on where the lights are, where the camera is, what the set looks like. It does not tell you everything mind. For example, sometimes lights will be hidden behind other objects or bounced off walls, so acquiring additional photographic reference of the set is still recommended. But for how things look in a specific location, it is gold (well, chrome). Malcolm’s army approaching the castle and the battle (when Dunsinane is sieged) is the climax of the story. The Pointer’s gamut is (an approximation of) the gamut of real surface colors as can be seen by the human eye, based on the research by Michael R. Pointer (1980). […] What this means is that every color that can be reflected by the surface of an object of any material is inside the Pointer’s gamut. A possible improvement of this post could be to generate two charts : one for Diffuse Reflectance and one for Specular Reflectance. Sounds like some interesting homework for the future ! Links After reading Chapter 1 (about Color Management) and Chapter 1.5 (about ACES), you may ask yourself : where do I start ? How do I set correctly all these values ? Sometimes we struggle to balance correctly the look development of our assets between texturing, lighting or grading. For example, how strong should be our lights in a turntable ? Or how bright and saturated should our textures be ?

But ideally, our v001 published ‘look’ and ‘light rigs’ have been calibrated. Whether that be for VFX, full CG or games. From that point onwards, you can be as creative as you need to be. However, you just need to be aware of this and tweak your digital Grey shader to compensate. Or if you have the time and resources, shoot your look dev reference kit under polarised and cross polarised light to capture the surface colour more accurately. Let’s take charcoal as an example. Charcoal not being a pure lambertian surface, you will get some “specular” reflection at grazing angles. For artistic control in CG, we generally split diffuse and specular reflections but in real life they are just really the same. Great explanation by Thomas Mansencal. Diffuse Color or Albedo AOV ? We could definitely think about developing an application allowing us to compare our base color textures to the Pointer’s Gamut. A few studios have already developed some solutions internally and an open-source software would be more than welcome for the community.Studios have provided different answers to this issue : how do we limit the albedo range to a PBR one ? Here is a couple of solutions I have seen : If you set your Base Color (or Diffuse Color) directly in ACEScg, it is important to be aware that there should be some limits in terms of saturation and luminance. One may ask : what would be a proper limit for the Diffuse Color ? If you are a fan of mixing science with art, or maths with creative thinking, then join our Connection Programme, where we’ll be exploring VFX, animation and games from the core fundamentals: