We talk a lot about shadows in drawing, but it’s super important to also think about how light reflects off different surfaces. That determines highlights and other things we need to see for figure drawing, landscapes or objects. This time we’re going to train our eyes by observing things we would see during daily life, and also by doing studies of some master artist’s drawings as well.
Two types of reflection
- Broadly speaking we can think about two types of reflection – diffuse reflection and specular reflection. These sound like tricky term, but you’ll be super familiar with both of them. To explain this, I gathered all this scientific equipment. Once we’ve explored both types of reflection, we’ll think about what it all means for how we draw people.
Specular reflection is what you normally think of when you say the word reflection. Your face in the mirror, those really bright bits on something shiny. It just means that light rays are bouncing off a smooth surface, smooth at the microscopic level, so that the light rays bounce back off the surface like this.
A lot of surfaces are not smooth enough to give out a lot of specular reflection. When the surface is rough at that microscopic level, the light bounces off it, but it bounces off in every direction. A piece of paper, even though it seems smooth, is rough at the microscopic level, so there isn’t much specular reflection, it’s mostly diffuse reflection. So there is still light coming off these objects into your eyes, so we can still see them and actually this sofa, my tshirt, we see most of this stuff in the world because of this diffuse reflection.
With specular reflection you can see a lot about the light source itself – where it is coming from and often even its shape. With diffuse reflection, that information is lost as the light is scattered all over the place.
Diffuse reflection lets you see the object itself better. With glossy paper, I get a lot of specular reflection so it’s hard to read in strong direct light sometimes, but when it’s just normal matte paper, it’s a lot easier.
Where are your eyes
For diffuse reflection, your eyes could be here or here, as long as the light can reach your eyes, the lighting on the thing will look pretty much the same because it’s pretty evenly scattered. If your eyes are here they get some light, if they are here, they still get some light.
Specular reflection though differs based on where your eyes are. Here you get this light, almost like it’s coming direct from the light source. Specular reflection bounces light in specific directions, not all over the place, so your eyes only get the light that is coming off the object from a specific angle. To know if you’re seeing specular or diffuse reflection, move your head a bit and see if the reflection moves as you move.
Where is brightest?
How bright the diffuse reflection is depends on how strongly and directly the light is hitting the object. On this ball, the light is hitting strongest here and that’s the brightest part in terms of the diffuse reflection. We could move the camera, and that would still be the brightest spot.
But the specular reflection is not about where the light hits strongest, it’s about where the light is hitting such that the light will bounce right into our eyes. So on this slightly shinier ball, you can see the specular reflection, and it’s moving as the camera moves. It tends to be very bright.
Different surfaces in the real world
So during daily life, you can see all sorts of mixtures of these two types of reflection. Some surfaces have a lot of specular reflection, like chrome stuff or the smooth surface of a puddle. We can see not only light direct from light sources reflected into our eyes, but light from everything reflected off those surfaces.
Some surfaces seem to have quite a bit of specular reflection but their surfaces are not perfectly smooth so the reflection is a little murky. You can see some of the actual colour of the object too, as well as the reflection.
Some things have almost no specular reflection and only diffuse reflection, like bricks or unvarnished wood.
Some surfaces have mostly diffuse reflections with a little bit of specular. So on this ball, mostly you see the ball itself. If we move around it, the light on the ball is the same. But we also see a little bit of reflection direct from the light source here. You might see a lot of art tutorials that explain light using a sphere with some diffuse and some specular reflection like this.
You might notice that with rounded surfaces or surfaces with more planes like on the rounded corner of something, somewhere on that surface, you’ll find a specular reflection pretty easily which I think is because there are more planes reflecting light at more angles. With a flat surface, you need a more specific angle to get the reflection because there’s just one plane reflecting light at one angle. That is going to be relevant to seeing reflections on people.
I found things get trickier to understand with certain textures where the surface is smooth enough to have specular reflection, but on a bigger scale is textured. Maggie’s hair is a good example. Her fur is very neat and smooth, so it has specular reflection all over the place. But it’s not a simple smooth surface, it’s made up of tons of fibres, each one with it’s own 3D shape kind of like a cylinder and together they create a surface.
I wanted to understand what was happening so I used the rounded handles of these table knives tubes thinking they are like her fur made big. Each handle has a curved surface which reflects light in the specular way in a lot of different directions, so they all have some specular reflection that finds the camera lens wherever I move it. So I get a line of specular reflections across the handles.
Maggie’s hair is like a load of shiny tubes neatly lined up, because she’s such a shiny beautiful dog. So the same thing happens, and I get a line of reflections across her fur. And we saw that in our hair drawing tutorial, highlights on straight hair tend to cut across the direction of the strands.
With this brushed metal I think roughly the same thing is happening. It’s got this grain going this way, and the specular reflection cuts across that.
Skin has both!
Skin will have bright areas where the light is hitting strongly and there is a lot of diffuse reflection. Those are based on which parts of the skin are facing the light most directly. But skin will also have really bright areas where there is specular reflection just bouncing right off it into our eyes. We aren’t super reflective like chrome, but there is specular reflection. It’s fairly muted and subtle, sometimes blending quite nicely with the normal diffuse reflection.
You can see the specular reflection a bit more clearly on people with darker skin. I give a visual demonstration of this in the video HERE
Our bodies are made up of curved 3D shapes, there’s a lot of roughly cylindrical shapes especially going in various directions. So where there is a lot of plane changing, like we saw with the knife handles, it’s likely there will be some part of those curved surfaces that happens to be at the right angle to bounce light from the source right into our eyes and we’ll get specular reflections – so you’ll often get highlights to draw where planes are turning.
Using this in drawing
So here Mayko is doing some studies of a drawing by LdV and another by Jacob Jordaens. Often when drawing on white paper, you’ll merge bright areas from diffuse reflection and specular reflection and leave them all with the white of the paper. They’re different but in the end, this difference between light areas and dark areas in the shadows is more important. But if you can find a way to bring out the really bright specular reflection, or the especially bright bits of the diffuse reflection, it helps add to the 3D feel of your drawing. Ideally, you can do it without compromising that contrast between light and shadow which is more important.
A great way to do this is to draw on toned paper. You can then use white to bring out the highlights and your charcoal or something for the darks. Areas of diffuse reflection can stay with the neutral toned paper. That is what Mayko is doing here in these studies, and it’s something we demonstrated in a video about the trois crayons method.
The lines of these highlights can really help explain the shapes we are looking at. We are asking people’s eyes to interpret our marks on a 2D surface as 3D shapes, so we have to give some clues and the highlights can help in two ways. The way the highlights run over the surface help explain the volume, just like the edges of the shadow shapes do. Secondly, where we put our highlights explains which bits are all at this specific angle to the light source.
You might keep your white highlights to specular reflections or you could use it also for the brightest areas in the diffuse reflection. We don’t have the original reference to study, but as she did these she felt that LdV was keeping his highlights to specular reflection, whereas Jacob was using the white more liberally for all the fairly bright areas.
If you didn’t want to use toned paper, some artists like to apply a lot of midtone right across the white paper, and then use an eraser to let the white of the paper show through. But as I said before, another approach is to use the white of the paper for all the light areas, both diffuse and specular reflection, and focus on drawing the shaded areas.
So many beautiful ways to draw, so many amazing visual phenomena to see during daily life, I hope you enjoyed this edition of our training your artist eye series and maybe take a few moments during your days to notice some of these different reflections.
One final note – if you haven’t checked out our Fresh Eyes challenge, I’d highly recommend that you take a look! It’s a FREE ten-day drawing challenge all about transforming the way that you see the figure. The challenge is suitable for all abilities, whether you’re a complete beginner or an experienced artist.