If you render this out, you should see something like so. You won’t need any lights as this is again, just flat colour. If you review the values of swatch 22, you will see that you get a value of 0.191. Whoop! Whoop! The fresnel in the diffuse_albedo is a result of the Specular IOR and how it affectsthe albedo of the diffuse to make it energy efficient.So with no Specular, there would be no fresnelon the diffuse_albedo, as all the energy would be in the diffuse. From the Arnold documentation. So, in a nutshell, if you are not matching directly to reference, then present your model within a nicely lit environment. With or without the reference – up to you. I personally would go ‘with’ as it allows the reviewer to get a sense of the lighting used in the scene. This is what the OneShot looks like in Apple Color. I’ve zoomed in on the chart to exclude the rug and eliminate color elements that might be distracting on the scopes. The image is obviously blue overall, and that’s easily seen not just by eye but by looking at the vectorscope:

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… Colorspace 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. Well, everything is contextual, anchoring your values in the real world, as a starting point, is often the key to greater quality, this is to a degree the basis of PBR. Keep in mind that Pointer’s Gamut is about reflectance only […]. It is about Digital Asset authoring, specifically Look Development of shaders and textures where more often than never, one needs to strive for physical accuracy. […] This is not about image quality but physical correctness. Like any tools, it must be used with understanding. PBR validation tools […] arguably help improving Lookdev consistency and overall image quality. A group of ruffians conscripted by Macbeth to murder Banquo, Fleance (whom they fail to kill), and Macduff’s wife and children. Porter What do all these definitions tell us ? That you get some specular/glossiness information embedded in the albedo value. That is very important.A Color-Rendition Chart (pdf) – Journal of Applied Photographic Engineering, Volume 2, Number 3, Summer 1976 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 Macbeth is duly proclaimed the new king of Scotland, but recalling the Witches' second prophecy, he arranges the murder of his fellow soldier Banquo and his son Fleance, both of whom represent a threat to his kingship according to the Witches' prophecy. The hired murderers kill Banquo but mistakenly allow Fleance to escape. At a celebratory banquet that night, Macbeth is thrown into a state of horror when the ghost of the murdered Banquo appears at the dining table. Again, his wife tries to strengthen Macbeth, but the strain is clearly beginning to show. 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 😉

But it is important to note that this is just from the position you are shooting the ball from. Move the Grey ball and it will respond differently, as it should. But for that particular point in space and time, you have captured an extremely valuable moment of reference. BibTeX record]: McCamy, C.S., Marcus, H., and Davidson, J.G., " AColor Rendition Chart," Journal of Applied Photographic Engineering 11(3) (Summer issue, 1976), 95-99. Using 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). After pushing the highlights, midtones and shadows away from blue and toward orange/red in Apple Color I ended up with these results:

Whether you are on a film set or in a controlled lit environment for look development, it is important to capture your reference in context. I generally tend to use one of the 2 scenarios below:

First of all, a very basic question that has bothered many people. Why is it called Pointer‘s ? It is actually very simple ! In 1980, a scientist named Michael Pointer took over 4000 references to study their colors and came with a Gamut named after him. What you should NEVER do is hold up a Macbeth chart in your current environment against the image you see on the screen. You may want to use these values with “a pinch of salt”, since we don’t know exactly if they are strictly about diffuse reflectance or albedo. From the render tests I have been doing about charcoal, here are some more accurate values (which match the ones from Unreal Engine) : The best thing to do is actually measure the reflectance of your grey ball and then create a digital shader to match that. This is something we’ll document later on. Onset Training

True-to-life image color reproduction.

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 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 ? 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