What are materials and textures? How can we see transparent objects? What makes a picture a picture, not a collection of objects? How do we mix reflected colors? Read on, and your work will become even more realistic!
- Learning to see light and shadow
- What is color?
This is the last article in the series. In the first article we studied the theory of light and shadow, in the second we talked about colors and shades. And today we will learn several advanced tricks to make your work realistic. If sometimes the objects in your drawings are flat and lifeless, then this lesson is for you!
Materials
Most of the problems with colors are associated with surfaces. The surface structure creates both color and brightness that we see, and there are many nuances and subtleties that need to be taken into account. If we do not do this, we will always receive fake, inanimate drawings. This is the eternal problem of beginners – so let’s leave it in the past!
Mirror and diffuse reflection
In the previous article I mentioned gloss, but then I didn’t focus on how important it was. So we know that reflection can be specular and diffuse. Typically, objects reflect light and mirror, and diffuse, and the end result depends on the ratio of these two types. It turns out that we see matte surfaces, glossy, matte shiny and so on.
As we already know, the mirror reflection is obtained if the object reflects the rays of light at the same angle. The more mirrored the surface, the clearer the reflection it gives. The shiny surface can be caused by both the peculiarity of the material and the humidity.
It is safer to treat materials as partially mirrored. After all, even a little plush glitters in the light. Using different levels of mirror reflection is important for the realistic picture. Glitter certainly looks beautiful, but if every object in your picture glitters, it is not good.
Pure mirror reflection does not always reflect light in its original form. It works as if only a “mirror layer” reflects colors. But the red ball can reflect the highlight of the green shade. This is an interesting effect for some gems, fabrics, and so on.
The level of specularity should also be used to show how smooth the object is. Smoother surfaces better reflect the light, respectively, an old, shabby wooden table and a polished wooden bowl will reflect light differently.
The reflection depends not only on how smooth and polished the surface is, but also on what material it consists of. Each surface consists of particles, and each particle gives its flare and its shadow. Therefore, simply applying a translucent texture to an object does not give a good result. Each texture, superimposed on the object, reduces its susceptibility to specular reflection. Compare yourself what looks better:
Fresnel effect
The reflection depends on the angle at which we are looking at the object. The smaller the angle, the cleaner the reflection will be. This effect helps a lot to find the perfect place for an object, helps to position the object so that it gives the desired reflection. You can check this effect at home on the floor – the lower you lower your head, the cleaner the reflection will be.
Transparency and refraction
Transparency is problematic, because it is almost impossible to make an object realistic in the figure. Simply lowering the opacity value will not give the desired effect — the object will appear ghostly, rather than transparent, like glass. This is because our understanding of transparency omits some important details.
Let’s see how it works. For example, red glass absorbs waves of all visible frequencies except red. That is, roughly speaking, this is a kind of color filter.
It is logical to assume that a fully transparent glass transmits the entire frequency range of visible light. But then, if the rays do not interact with the glass, how do we see it?
If you carefully read the previous articles, you know that only 100% matte materials do not reflect anything. So even perfectly clean glass has little mirroring ability.
An interesting fact: the mirror reflection is what turns the clear water into, roughly speaking, a mirror.
But how then can transparent objects give shadow? It’s all about refraction – the ability of the rays to be refracted inside a transparent object. Using this phenomenon will give volume to transparent objects in your picture.
You probably remember this scheme from school physics. We need to remember only one thing: the thicker the material, the more rays will be refracted.
It turns out more interesting if the material is curved, that is, if it is a lens. Lenses can collect or scatter rays. And if the rays are focused at one point, shadow areas appear. This is how transparent materials give shade.
All transparent objects with a curved surface – lenses. Each convex lens can focus the rays at a single point. A glass of wine, a bottle of water, and even a simple drop – all these objects cast a shadow and focus the rays at some point. If the lens is colored, then the highlight in focus will be the same color, respectively.
So what does a lens do? She changes the image. This is the most important thing to remember when drawing transparent objects.
Translucency and subsurface scattering
Why objects do not completely pass the light? Look at the situation below. Leaf on the background of the light source looks brighter
The mechanism is simple. Some materials are translucent. Some rays of light, which seem to be absorbed by the material, make their way through, so the impression is made that the object itself is “highlighted”. Naturally, the thicker this material is, the less rays penetrate through it.
The most striking example of translucency is human skin. Subsurface dispersion is most apparent in the softest parts of the body, such as the ears or nose, but it is also present in other places. If you do not take this effect into account, the people you draw will look like statues.
And how does this effect on the color? The color becomes brighter and richer, and it can also become warmer.
Subsurface scattering on human skin is a separate topic, but I can give you material that can help you:
Ambient Occlusion (AO) shading model
The light source does not leave much room for shadows. Therefore, there is a risk that the picture will look flat. To fix this, you can focus on absolute shadows — those that are independent of the light source.
Using AO does not give you 100% realism, but it is quite a powerful tool. You can read more about JSC here.
Fluorescence
Some materials are able to transform invisible light into visible. Such objects reflect more light than we see around, so it seems to us that they are shining, although in fact they do not generate light themselves. You can use this effect to add some magic.
Light emission
Sometimes we may want to add a light source to our picture. Considering how much we know, it’s like a piece of cake! The brightness depends on the power of the source, and you can choose the tone and saturation yourself. Just do not forget that the light source does not cast a shadow.
Consistency
I drew this picture about two years ago. As you can see, the composition is beautiful, the anatomy is taken into account, the colors are well chosen, but … the picture does not look like a single whole. All objects (Santa, dragons, deer) in their palette and in the picture can not see the connection between them. And how between them there can be no connection if they are in the same situation, under the same light sources?
Color light
Of course, in a good way, this is a separate topic. The sun gives white light, and for us it is familiar, like many artificial light sources. By the way, in the last article we found out that sunlight is not neutral white, it can be warm or cold.
The tone of the light source affects all objects in the figure. Look at the pictures below, you probably can immediately tell which photo is warmer and which is colder. Both photos are beautiful, just one of them is supposedly shot on a sunny day, and the other is overcast. The most interesting thing is that if they were not presented to you side by side, you would hardly be able to see if it is a warm, different photo or not – everything is known in comparison.
Sometimes photos look too “yellow” or too “blue”. This is because the camera shoots what it sees, but we do not just see, we have a brain, which sometimes imperceptibly changes the real picture for us. Photographers have to think how to make a photo warmer than a bit colder, and our brain does it all on a subconscious level.
What does this mean? You can call a color white, even if the color does not look white under certain circumstances. You can check it, for example, in the evening, when all the paints are getting colder. You can say that a piece of paper is white, although in the evening it is not so – it simply cannot reflect the whole spectrum. This effect is called chromatic adaptation, and it can create various illusions.
The circles on the right seem to us red, blue and green. The brain changes the background color to white and calculates what color the circles should be.
Of course, this is an illusion. Their real colors are purple, blue and cyan. You can use this effect. Since we work with a digit, we can simply put a blue filter on top, for example, but this will limit us to only one light source. How can we predict how the colors will look under the coloring light? First we need to understand how this mechanism works.
The circles above are painted in the same colors as in the right of the previous picture. If you do not believe it, check it with a graphic editor.
For reference, when white light (and by definition it includes waves of all colors) shines on red, all colors except red are absorbed. Only red is reflected in our eyes. White objects reflect all colors. Understanding this fact will put greater power in your hands, and we will use it in the future.
What happens if we remove from the light all colors except red? A red object will also reflect only red, but a white one that reflects all colors will also be red! Both of these objects will be the same.
Now let’s just leave blue. A red object will absorb blue and will not reflect anything – it will look black to us. White will be blue, as it reflects all colors.
The examples above are not very qualitative – in nature this happens very rarely. Typically, colored light includes all colors, albeit little by little, and objects do not become pure red or pure blue. Let’s model a more realistic situation and see what happens.
The object in the picture is shiny and dark green. Its color is not pure green, rather a combination of red, blue and green. As you can see, some of the rays in the first picture are absorbed (this is how photosynthesis happens), but still a small part is reflected. But if we change the luminous flux from white to orange (red and slightly green), then the object will reflect only the red and green rays. The ball is still green, but you will clearly notice the differences.
You can easily carry out each of these experiments yourself, using the monitor as a color lamp – wait until it goes out, open your image editor in full screen mode and fill the entire space with the necessary color. Of course, you do not need to repeat this procedure every time you draw something under the color light. To understand how color should change, answer the following questions:
What does an object need to show its colors?
How many and what colors come from the light source?
We have two colors – the color of the object and the color of the light – we need to find out what color it will end up with. A yellow object and a magenta light will give the same result as a magenta object and a yellow light. So what matters is what the colors are, and we don’t care what color it comes from. To simulate color mixing on a computer, use the Multiply blending mode in your graphics editor.
This is an interesting thing. Do you remember the subtractive mixing that we discussed in the last lesson? So, this is the same thing! And this means that you just need to use the four rules for subtractive blending from the last lesson to get the final color. Real artists have no problems with this, but we work with the figure, and we need to know some rules.
By reducing the color saturation, you reduce the amount of that color in the picture. The brightness depends on the brightness of the dark components. A small amount of paint means that the object gets mostly white color, of course, with a small admixture of others.
Brightness can be considered as the amount of light in the environment. For example, at night the light source is dark blue, and all objects appear dark. In the films, the night is mainly shown by coloring the picture in blue, and everything remains bright.
The brightness of the picture falls most of the time, and although it is quite realistic, realism is not always welcomed. For example, real night photos are very, very dark, and the resulting blue tint is the result of the camera and Photoshop. But we want to see a better romantic blue hue than the dull outlines of objects in the dark. Thus, realism is not always needed – as in many other moments of art, you must always add something from yourself.
Color mixing and reflected light
The process of reflecting colors is important so that the picture is a single scene, and not just a collection of objects. The common mistake is to work with each object separately – you need to work with the picture as a whole. Reflected light is nothing more than colored light reflected from other objects and incident on an object at an angle different from the angle of incidence of light from the main source. That is, everything is subject to the rules we have just talked about.
Here is another rule that you must remember – bright light always interrupts light that is weaker. This means that the reflected light will never be stronger than the main light source (although it can be the same if perfect mirror image is involved), and this will only be observed in the shade. And if the reflected light is darker than the shadow, then it will not be visible – there is no such thing as “black light”, there is only the absence of light. If you see a reflection of a dark object in a bright mirror surface, this means that you see only a bright outline of the object and the absence of reflection in its place.
But reflection is not only that light is reflected between two surfaces. This is also how and where it is reflected. Here are some rules you should keep in mind:
1. Fully matte surfaces do not reflect light at all.
2. Fully mirrored surfaces reflect everything – they work as a source of light with sharp corners. They are able to make an object as bright as a light source can do, directly illuminating it.
3. Mixed surfaces (partially opaque, partially mirrored) reflect as much light as they are mirrored.
4. Dark surfaces are dark because they absorb most of the light. Thus, they do not affect matte surfaces, and only their shadow is reflected on glossy surfaces.
5. White objects reflect everything.
Mixing light sources
Let’s talk a little more about light sources. Because they create light, they strongly influence the picture we see. There are several types of light sources:
1. Sunlight is a strong but diffuse light source. Its shadows can be sharp or soft depending on how powerful the light is.
2. Directional light source – strong, with sharp shadows. For example, a flashlight, or sunlight breaking through a hole.
3. Reflected light – light reflected from one object to another.
4. Scattered light – diffuse light without a specific direction. For example, sunlight in cloudy weather, reflected from the clouds.
5. Transmitted light – light passing through a translucent object.
Mixing these light sources will help you create a beautiful, attractive picture. Beginners usually focus only on sunlight, as it is the most obvious. One way or another, it creates large dim shadows that fill the entire space. Diffused light helps smooth out these shadows and show the shapes hidden under them. At the next level, the artist learns to link objects in a picture using ambient light. Sometimes you have to take into account the transmitted light. How to manage all this chaos?
Even if the picture looks flat, you will need to use a perspective for lighting. You can’t give a damn about this rule – shadows and highlights appear on the shapes, not on the planes. Lateral lighting is most used, as it is simple – to mentally position the light source to the left or right of the two-dimensional surface; however, they are often abused, and such light becomes dull. If you want to take full control of the lighting in the drawing, you need to plan it well.
Let’s imagine that you want to portray a similar composition. It doesn’t have to be that simple, but every scene in your head can (and even should) be simplified to its primary forms.
And now you can change the perspective. Take a piece of paper and draw a front view of your composition and / or top view. So you can place the light source at any angle you want. You will also see how objects interact, and how shadows fall or throw. The drawing should be as simple as possible, since, in any case, the shading of parts will be similar to the shading of the objects themselves. Perhaps you could have done without such measures in simple scenes, but when the composition becomes more complicated (unusual light sources, a lot of light transmissions), it is simply necessary.
Shadows
When you work with several light sources, including color, you can face a new problem – what happens to the shadows?
Diffused light is known for its ability to color the shadows produced by the main source of light. It never forms new shadows in the light zone, but such light can create its own shadows in the shadow zone.
The reflected light sometimes falls on the shadows, coloring them and making them brighter.
Passing light well destroys the shadows of objects. Sometimes, if he is weak, he only colors the shadow like a diffused light.
The rules state that the shadow should be an additional color for the light. For example, blue light creates yellow shadows and vice versa. Truthfully, this is only to some extent – we need two sources of light to accomplish this; moreover, it will only work if one source emits light of a primary or secondary color, and the second light is white.
This optical illusion is based on a very interesting mechanism of vision called color counteraction. Cones are not the only mediators between what we see and our brain. Surprisingly, the three signals are not transmitted directly, they can pass through three channels: the red / green channel, the yellow / blue channel and the white / black channel. That is why there is no bluish yellow – only one of these colors can pass through the channel at a time.
The main conclusion we have to make is that our brain sees red not only because it receives a red signal, but also because it does not receive green or blue signals at the same time. When you see a yellowish (RG) shadow created by blue (B) light in the presence of a white (RGB) light source, this is because the shadow (RGB) is slightly less blue than the illuminated part (RGB + B). And for our brain, if it is not blue, then it is yellow! By analogy, if the subject is not light, then it is dark. The same with the image residual phenomenon – the white screen appears less red after we look at something more red for a long time, and therefore it acquires an additional shade (blue).
Of course, the coloring in this case is very thin, and if you ignore it, naturally, no one will notice anything. I decided to describe it because I noticed that people often use this rule without even trying to understand it. Most of the effects that seem to flow from this rule are in reality nothing but the result of diffused light (yellow sunlight — blue shadow from the sky, orange light from the lamp — dark blue night sky), so when you see strangely colored shadow, check the diffused light first.
What about the following rule: “warm light — cold shadows; cold light — warm shadows”? Well, in fact, this is true, but only if this rule is expanded: cold main light is warm diffused light and vice versa. Such a contrast is very pleasing to the eye, but this is not an impregnable rule that must be strictly observed everywhere and always. Only you choose the color of the diffused light. And, definitely, you should not add cold shadows if the diffused light is warm.
Conclusion
Well, that’s all the basics of the theory that you need to know. Of course, we have dealt with these topics superficially, and in the future you will need to study them more deeply. If it seems to you that you have to learn too much, remember – it is not easy to draw. It may seem so when you see how professionals create masterpieces in a few minutes – but all this thanks to years of study! Drawing is not just putting colors on paper, it’s knowing how to do it, how it all works, how everything should look and how it shouldn’t. If you want to become a professional – do not rely only on your feelings and your talent. Take time to study the theory, all that is hidden behind the scenes. You will be surprised at how many of your internal questions the theory can give an answer!
