Illustrate Color & Light I: Ambient Light

1. Introduction and the Class structure: Hello guys and welcome to understanding color and light series of lectures, series of classes. This class is going to be about ambient light. We're going to talk a lot about ambient light in this class and we will be creating this particular image during this class. A few words on the class structure. Each class, including this one, consists of few subjects, not including introduction and conclusion, of course. These subjects, each one of them has three steps starting with theory, then example, and the class projects. So, you will be basically doing only the class project, the theory part and the example part will be only seen. You'll have to watch the video and then you'll be approaching your own class project in the third part. Also, few words on what we will be doing and what we won't be doing, and what we won't be talking about in this class. We won't be dealing with any software issues at all. We won't be talking about brushes, or do presets, or Photoshop at all. I will be using, of course, Photoshop for the matter of explanation, just to explain you better the main principles, but the software here is not an issue. Software here is not an important things to talk about. We will be talking a lot about theory, about physics, about optics. We'll be talking about more general approach to rendering things using some particular software. We won't be talking a lot about color theory. Once again, we will be talking a lot about light but not about the color. Also, we won't be getting too deep into building shadows. I am into perspective. You have to learn these, to gain this knowledge by yourself unfortunately because this is too complicated issue and issues, and you have to somehow deal with them by yourself. This class is not about that. This class is only about light and understanding the core, the essence of light. Okay. A few more things. Just to give you a little sneak peek into the future classes in the whole series, this is the sketch we'll be starting from and we will eventually get through these, and these, into these. That is where our first class will be ending at. The second class, we'll be talking about direct light. Oh, sorry. We will be talking about color, and we'll be adding color to this image, and we will be getting this image at the very end. In the third class, we will be talking about direct light, and glossy and reflective surfaces, light scattering and hard shadows. So, that is more or less it for the introduction. So, I believe you have the basic picture of what we will be doing through the whole series, and let's start with our first subjects for the first class. 2. Light diffusion: Okay. Let's start from the basics. How we see life, how we see objects around us. Well, it's kind of obvious question and obvious reply would be that we see them by the light that they reflect on us. This for example is, this is a trajectory of single photon. We'll be talking about photons later more in depth but right now what is important is that these photon is being reflected by this surface into our eye and that is the reason why we see, why we see this object. Okay. That is obvious, yes but what is not so obvious that each time the light is being reflected, unless it's a perfect mirror, each time the light is being diffused, it means that each time photons even if they were initially parallel to each other, the trajectories, the light ray was traffic like laser for example. Each time they hit the surface, they are being diffused. They are being reflected in different directions. Why that's happening? That is happening because if we make it closer into the surface, this line for example, yes, we will see that most of surfaces around us are not perfect. They have bumps. They have really random curves or random bumps, I don't know. Therefore, each time photon hits the surface, it's being reflected in different way. And that is important to understand why because here a little example. This is some object yeah, some surface. Best way we see it is when we look at if it's straight, 90 degrees. But if we start turning it around, we will see this surface. We will still be able to see it, to see the surface. However, we will see it a little bit slightly more dark, a slightly darker tint like this one for example. This gray square we see at 90 degrees. And this one for example, it's very approximate, it's very rough approximation but this is more or less what is happening. When you turn surface out of view, away from you, you will feel that surface is being slightly more, it's becoming slightly more bright and slightly more central but it's not important right now. And of course, we will see, we will still be able to see the surface. Why? Because some of the lights, some of photons that are being diffused, they still reach our eyes but not all of them, not most of them. Most of the photons we are really able to see when we look straight at the surface. And that is really important thing to understand. Here's a little example. Two cubes, they are not perfectly, best drawn in terms of perspective but I believe you will get the idea. Here to the surfaces are the same angle towards us. Therefore, they are absolutely identical in terms of values, in terms of their color and brightness if you want. This one - actually, this is not correct, but nevertheless this one is brighter than this one because the the angle of this one is closer to 90 degrees. This one will be darker and these are the same color because their angle relative to the viewer, to us is the same. So, you can encounter pretty much easily a situation where you will see two adjustment surfaces, two adjustment faces which would be the same color, same tint. But if you see surface that turned away from you even if it's really a little turn, it will still be noticeable. Okay. That is the theory. Let's do some little exercise. Let's see some little example. 3. Shading a sphere: Okay. Let's draw a sphere. Here we go, and let's shade it a bit. I took just random grey color but it can be brighter. It doesn't, actually it doesn't matter. What matters is to show the transition between the surfaces, different surfaces, different angles of surface. Okay. Let's take a slightly darker color and then start beginning to shape, okay, and shape. Okay. We'll make it a little bit more dark. I don't use here an automatic gradient like in Photoshop here because these are not correct gradients. They, in terms of right curvature of the sphere, these are not suitable. We can't use them here, but we can do it manually. Okay [inaudible] this one this way. Okay, and here. Once again, this transition between the dark surface, dark barrier, and bright one should be really, really subtle, really, really almost unnoticeable, I would say there, this way. Okay. Maybe, just maybe, it's a little bit too dark so we can make it more, this is more or less what is happening in real life. So, for example, if I would, I can make this sphere more bright and this still is going to work. This one will be too dark. This one more, this can happen also, this transition, but for really complex surface like car paint or human skin, for example, the opposite where the center is darker than the outer border, is also possible, but that will mean that we're dealing with also surface that is not usual. For example, it can be or really glossy surface with lit from from behind, or it can be hairy like a peach, was little, or human face for example. There is little facial hair here, or some really as in the case of car paint, some really complicated multi-layered paint, multi-layered surface, but in most cases, you will see this. So basically, this is the first, your first tool to create volume of any object by looking at angles of the surface, angles from which you see the surface, and making the more turned away from you. Then, as the surface is more, turned more away from you, you make them more dark, and that is your first tool. By the way, same principle works with big plane surfaces like ground earth for example. If you see a huge, let's see. Let's make it, we should see, big, big surface, big ground plane, to whom would be the same color. It will be more like this all the way, especially if the distance between you and the far edge of the surface or horizon is really, really, really big. Why this happening, same principle, because when you, for example, this is your surface in. This is you, and you look at this surface from different angles. This angle is different from this one. Therefore, this at this point, you'll see something like that. This color is this value here, it will be a little bit darker, a little bit more, and a little bit more, but once again, it is noticeable only on big surfaces, really big surfaces. Okay. Here is a theory, here are the two little examples and let's do our class project. They are far apart. 4. Rendering simple volumes: Okay. Here, I created this sketch. I created it within Photoshop, so it's simple. This colonnade, and then outer in the middle, that will do the job I believe. I created this sketch, made it a bit more transparent, and for the sake of this lesson, I just separated different parts of this sketch into different layers. It really don't matter here. But what matters is that we start from really basic one color for the whole composition. I will adjust it later, and I will make it sometimes brighter, sometimes darker. But each object we paint, we can start with simple grey base, grey color block, and then we can add darker surfaces, darker, more grounded surfaces and stuff that fades away from us. We can add darker tints, and that will create the first impression of volume of this object. I won't do it here, I'll show you the result, but I will explain you. Here we go. That is the same colonnade. I can place on grey layer just to be more obvious. Now you see these little pillars, columns. The very same principle as I did with sphere, I do it right here. Here the very same principle as I did it with cubes, and here very subtle, very gentle transition from the 90 degrees to zero degrees. Here, these two surfaces are not the same and go towards us. So, this is going to be not much, but this is going to be darker than this one. These surfaces, we barely see it, we see only, it started way pretty significantly, so it is one of the darkest surfaces here, almost like this one, it's more or less the same angle. So that is our start, that is our base. So if you want to create a very magic looking object, what you need to do is to start with simple basic solid color block and then you need to add some darker areas depending on viewing angle. But what you really need to do is to keep it really, really subtle and gentle, because the darker you make this drawing, and the harder you make this transition, the less you will see the volume, so the key here is to keep it really subtle, really gentle, really nice transition, almost invisible. Sometimes even on the verge of visibility, this transition is good and it still works. It is really good tool to use, and it is really powerful tool for creating all magic objects, but just keep in mind that it has to stay really, really subtle and really, really gentle. 5. What is ambient occlusion?: Our first tool for displaying a paint, shading, object volume was light diffusion. Now, we will talk about light absorption. What is light absorption? Here's our surface and here is our light rays or photons. They heat the surface and they bounce off the surface away, but photon can be- when it hits the surface, it can be either be reflected or be absorbed. It can also be- sometimes if the material of the surface is semi-transparent, the photon can get inside of it and be refracted for example, like in case of water or box or cheese or something. Something that is semi-transparent or transparent. But if our surface is not transparent, then the photon can be either be reflected or be absorbed. When it's been absorbed, it transfers its energy into heat, but it's not important right now. What is important that there is always a chance that photon will be absorbed by the surface. The amount of absorption of the surface depends on its color. For example, bright surfaces reflects more light than dark surfaces. That is the reason why we see them as bright and dark. Because when it is dark, it means that it reflects less light than the white surface, like the white paper for example. So, photon can be either been absorbed or will be reflected. That is important to understand. Here, these are going in, but not going out, and these black trails are going in and going out. What does it mean practically speaking? Practically speaking, let's imagine two adjustment surfaces. Two, like a tight place or some corner or something like that. Photon's light rays get into this tight place and being reflected. They bounce of each surface, they can bounce almost indefinitely many times, but each time there is a chance that some of these photons will be absorbed by the surface. That means that for example, we have 10 photons getting into this place, but only five or three or even one going out. Just because more times the photon jumps, bounces, the bigger chances that it will be absorbed. Practically speaking, once again, practically speaking, what it means, for example, if we have some kind of surface, mainly this plane, and this one. It's not that correct, but it will do. Okay. So, what happens here is that light will hit one of the surfaces, one of these faces, then it will bounce, bounce again, and get out. Once again, the very same thing. But some of the light won't get out. Some of the light will be absorbed and it means that these tight places, close to the corner will be darker. That is called ambient occlusion. Slightly dark and not too strong, not too dark, but slightly, just a little bit dark. They are the same. The amount of darkness on both sides of the end of this corner will be equal. Even if for example, we will make this plane for example, much, much darker itself, oh sorry, the amount of darkness will be equal. Make it for example, almost light, almost white, they will be the same amount of light fading within the corner. That is really important to understand, all that fading and absorbing of photons idea because it gives us the second, and I would say most powerful tool for creating volume of objects. Basically, you can create volume of object you can paint, volume of objects, only with these two tools, with light diffusion and light absorption. These tools will do the job just perfectly, and I will later show you some examples where I used only them without any direct light and it worked okay, just fine, perfect I would say. So, that is our main principle. Photons can be absorbed by the surface and the more obstacles they meet, the more times they bounce, the more chances they will be absorbed. Okay, one more into principle. Say we have a sphere and we have a whole bunch of different light rays that are coming from different directions. They will eliminate the sphere pretty much equally, unless we have something that will be blocking them. For example, the ground plane. In this situation, we will have more light coming from above, from the sky, from the ceiling from artificial illumination, than from the ground plane. Of course, there will be some bouncing light from the ground, but most of the light will come from above. Therefore, our sphere will look like this. Here, in the place in the area that illuminated less than the others, we will see the darkest spot, the darkest place. So basically, the principle is really simple, the surfaces that are facing up are brighter than surfaces that are facing down, but with some exclusion, of course, exclusion. For example, we have another obstacle for the light, another plane here. So, the light will come from all possible directions except from below and from this side. So here, we will see another shadow. It won't be shadow actually, it's not a shadow, but it is less saturated, a less illuminated area. So basically, the principle is done like that. You need to understand where your illumination is being blocked by different obstacles. Basing on these knowledge, based on these blocking, you'll need to adjust your lighting and you need to understand where most of the light is coming from, and that is your main principle. So, in most cases, it will be much simpler than this. You won't have these blocking surface. So, in most cases, you will have most of the light coming from above, and the darkest areas of your objects will be beneath them. So, that is in most case. But sometimes you'll need to take in consideration another obstacles and a bit more complex lighting situations. 6. Adding ambient light: Okay, let's take our previous sphere that was shaded in a previous lesson and add some ambient occlusion to it. Just move it a bit. I will also add some ground. Let's make it a bit more bright. Okay, here we go. So, we have a ground here, we have our sphere and we have our light diffusion on the edges of this sphere but now we need to add some, actually, I'll make it a bit more transparent. Now, we need to add some ambient occlusion. So, what I'm doing, basically, this would be our surface form, shape and according to this shape I will build this ambient occlusion. Let's makesomething like this one. First of all, all the lower half of this sphere will be more, more dark than the upper one. Okay. But also here at the very bottom of the sphere, we will have a really dark, dark shadow, almost, almost black because light never reaches this. It reaches there but it's been absorbed and it's too tight for the light to come out. Also, we will have, remember I told you that the amount of absorption, the amount of light absorption in ambient occlusion is equal on both adjustment surfaces? So here is the situation. The situation and that's how we saw it. This one is too strong. Sometimes, by the way, the light, the overall lighting is so strong that you actually cannot see this edge, this darker edge. Sometimes it really depends on your lighting conditions. Sometimes it will be like this. shadow but it's not shadow. It is shadow. But it's not shadow from that we're used to think about. It is basically a light absorption, it will always be blurred in case of if you don't have any additional light source. So that is more or less our second tool of grading volume of objects. Now, let's see how we deal with it in our class project. 7. Rendering ambient occlusion: Now, we will try to apply all these principles, all these laws to our class project. Remember this image we created before? Here, it's more visible. Theoretically, it is correct but it looks not too volumetric. It's not too three-dimensional. It looks really weird, I would say. But as soon as we add ambient occlusion, it will look just great. Okay. Here we go. Almost the same drawing, but here, first of all, I tweaked few things. I tweaked all these surfaces that are facing up. I made them brighter because of the light dome. Okay. I also made this hole a bit darker because- it wasn't here. Yeah, it was here. Also great, and I made this hole. She will be a fine print but I created this hole. I made it more because of the ambient occlusion as well but I haven't edited those shadows yet. So, I will be turning on all these layers that I put here, like this one for example. You see, it immediately gives us an feel of 3D of volume, or here, this one, all these parts of our object, our colonnade that are facing down, they have cast soft shadow, this one or this one, here and then the conclusion. Here on the- but the column and up of course, here and then the occlusion on the floor. I can destroy if I want but I don't need it. I don't think we need it. Okay. Here, once again, ambient occlusion in the quarter and here on the floor. Okay. It's always a good idea to the place your ambient occlusion shadows in different, in separate layer, just so your workflow would be more flexible, and, that way, you can easily make it stronger or weaker, the effect. So, it was good to be flexible with your workflow. Okay. One little touch, one little audition. Remember, we were talking about light dome where most of light rays are coming here some ways. Okay. Most of the light rays coming from outside of the object from above, not from below but from above and from different sides from around it. So, in this case, for example, light will be getting into this colonnade, inside of it, and some of it will be absorbed by these objects here and the by altar and by the columns, by the floor. Some of it won't get out. So, all these columns and all these objects won't be lit equally from all the sides, especially the pillars, the columns. So, the pillars will be lit more from outside than from inside, and these is what I'm trying to show here. I'm making it some really soft, very subtle shadow here from on the inner side of the pillar,. So, it gives us a feel of more light outside of the colonnade than from inside. I also add some little, tiny really subtle, really soft, gentle shadow also from outer light that will cast- that will create these soft shadows from the pillars. It's not necessary. You can- basically, we can turn this off and it will still look okay. Yeah. But for the sake of more realistic, more precise approach, more realistic image, it is always good to think about all these lighting effects and all these- all these light interactions between different objects and of course according to the shape of your object or objects according to your light conditions, according to your light source or sources. So, this is more or less what we wanted to achieve here in this lesson. Once again, we used here only two tools. We use here light diffusion. I mean, difference between values depending on the angles or angle view, and we used also light absorption and then the dilution. Basically, you can use only these two tools and create fully [inaudible] fully 3D-looking images, only with the these two tools. These are the most powerful and most basic and most powerful tools that you have in your, let's put it this way, toolbox. Okay. So, I think we are done with this ambient occlusion. Let's add some light source to our additional light source because we already have an ambient light source of this light dome around our colonnade. So, let's add one more light source and let's go into the sort of shadows. 8. Principles of soft shadows casting: Okay, a little bit more theory here. What are these soft shadows I'm talking about? Soft shadows are being cast by ambient light or light sources that are relatively big. For example, by light coming from inside the building through the window or light coming from above in a gloomy day when you can't see the sound actually but you can see light coming from the sky from different directions from the light dome. Even fireplace can be a good source of ambient light. By ambient I mean diffused light, diffused light which is coming not in one particular direction but in different directions. This light source, this light will create will cast really soft and nice shadows and these are the shadows we're going to learn to build. Okay, here's our light source. Here is our object Basically, our light rays photons will be emitted by this light source in different directions, not only here, here, here, here, here, here here, but also here, here, here. Basically, almost in every possible direction, there will be a light ray entering. So, how do we get out of this mass with some nice shadow. It is really easy thing to do. Okay, we take the farthest points of the light source and we draw a straight line light ray from the farthest point of one side of the light source and the farthest points of the object, in here and this one. Okay, now we're doing the same from this point to this point. What we get eventually we get this part. I do this one. This part will be darkest part of your shadow, will be your solid dark shadow. This one will be blurred. The blurr will go from 100 percent to zero. The transparency will be on the shadow, will be here 100 percent which means it will be fully transparent here and it will be zero transparency here. Here will be our solid shadow and that's how we build such shadows. Let's me show you this more in a visual way. 9. Creating soft shadows: Okay. Let's say we have a great ground plane in the wall, and an opening in the small or just some flat-screen that emits light. We have our object that will eventually cast a shadow. Let see. This one. So, what do we do now? We basically do the very same scene that I showed you before. We just draw all these nice lines, all these messy lines from one point to another, and also here, and also see here. So, this is going to be our solid dark shadow and this is going to be more blurred, more softer shadow. Let's add some light. Once again. because this light is ambient and diffuse so it goes everywhere in every direction, slightly fading out here but mostly going straight. Say four. So, we need to build a correct shadow here. What I could do probably, I could draw something like this, and this would be okay. Of course, it's too dark. I would need to adjust it but it won't be the correct approach to this issue why? Because placing shadow on top of your objects or a surface, placing a dark shadow and trying to adjust it, it is not physically correct. What is physically correct is placing a light and then excluding the shadow. That would be physically much more correct and that will give you much more correct results. So, I prepared this here. Okay. So, as you see, we have a solid shadow here, solid triangle here in more blurred. These two triangles, and that is how we build such shadows. Of course, I need to adjust my cube as well because it's not illuminated as it should be. These would be much darker of course. These are gonna be much brighter and these are going to be also brighter, more or less. Okay. That is how we build soft shadow. It's only main principle you can adjust it as you want. Of course, in each case, you will have to deal with different shapes, different objects and different light sources, but that is more or less the main principle when you have a solid shadow in the middle of it, and blurred shadow on the edges. What is really important to understand that here, maybe you see, here is softness of the shadow, the softness of the edge of the shadow, depends on it's distance from the object. So, here it's not even correct. The edge will be almost hard, almost, but then it will be more blurred. So, basically the shape of your shadow depends on few things; on shape of your object, of your soft shadow of course, on the shape of your object, on the shape of your light source and their placement, and on distance from the object. The closer your shadow to your object, the harder the edge. The more distance the softer the edge, that is the main principle. Okay. Let's move to our class projects and see how we add some light source, additional light source to our colonnade there. 10. Adding fire to the scene: Okay, I took this scene and I tweaked it a bit. I just made all the scene more dark. Just so we could add some light and it will be visible, more visible. So, the very same scene, the same composition, the only thing that I tweaked here, besides light, I added here some carpet. Basically almost nothing changed. Okay, let's add some light. Here is the fireplace and here will be the light, the fire. So, the light is going, besides that grey ambient light that we have here around the colonnade. We have now an additional light source and a very strong light source, because open fire or open flame is always, especially when your scene is dark, will be always the major light source in your scene. So, we have to here, to take an account all the light interactions. Well, not all of them, but most of them and we have to take in account that this is our light source and it is going to cast shadows, soft shadows, and it is going to illuminate all this scene, all these structure from inside, outside. Now, like this is the closest place, this is the closest surface to the fire, so it will be almost white. Okay, and here on these columns will be a slight, basically I'm just adding a light on top of the previous drawing, previous competition, I'm not changing it even a bit. Just adding some lights on top of it. Here, navigating also sunlight, and here navigating some lights too, and here is going to be, no, it's not so important right now. Here, let me get some, also sunlight. Here on the carpet. Here on the floor. Did I miss something? No. Nothing. Okay. So, basically what I did, I did everything we already know. I took my initially grey composition, I added some light diffusion to the edges of each object. I added some light absorption and light ambient occlusion. Now, I just added some soft light and soft channels. Well here, I have to give you a little explanation. Here, this is our light source. More or less. So, this light source will cast shadow just as like we did in previous lesson, in previous example. That will be going from here, for example here, that would be one shadow. One, not shadow, but one light we draw, and here, and that means that we'll start seeing light here, but it will be really absorbed, and then, we will see solid shadows at the edge of the competition. Basically here they're never same, and there, this one, this one. So we basically see really soft shadows, really soft light here on this, I don't know how it's called, but on this cylinder. On this thing here, on this step, and here on the ground, and that will fade away eventually and we blowed away in few meters from here. Here's the same situation. So light from this light source, will go to every possible direction, except for directions that will be blocked by objects like this one. Like outer that is blocking our light and this cylinder that is disk response. This disk that is blocking our light in these columns, that are blocking our light, and by the way, these columns also though they cast shadow, they do cast shadow, but the shadow, each shadow is very blurred as you see. Because of the form of our light source, our light source is really big so it emits light with every little point of it. 11. Summarizing the class: Okay, guys, that is it for our first class. I hope you enjoyed it. I hope you learned something valuable for you and helped you took something from this class into your toolbox. By the way, these two tools we were talking about through the class, the light diffusion, and the light absorption, and ambient occlusion, are so powerful that if you use them well, if you use them correctly, if you master them, if you understand them, you'll be able to paint anything you want. You will be able to render any possible 3-dimensional object. It will look just great. It will look amazing. It will look realistically. These are two tools that basically give you the basic feeling of volume. So, the only thing that you need to keep in mind when you approach these two tools, that the key to your success in the applying them to your work is that if you look around yourself, you'll see them in almost every possible direction, on the almost every possible place you will see the light absorption and the light diffusion. But you will also see that these two effects are really, really subtle. They are almost on the verge of visibility. However, they gave us the really great feeling of volume. So, when you approach these two tools, when you try to depict these two facts in your work, you'll need to keep them as subtle and as soft as possible. That is the key to success in this case. Once again, I hope you enjoyed the lecture and I hope you stay with me for the next class in the one after it for the whole theorists. Have fun with your class projects. 12. More Creative Classes on Skillshare: [MUSIC]