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2.2 Shadow Anatomy

To be able to create believable shadows, we need to have a solid understanding of what makes up a realistic shadow. In this lesson we take a close look at the different parts of a shadow and how to recognize when a shadow is incorrect.

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2.2 Shadow Anatomy

Hello everybody, Kirk Nelson here. Welcome back to mastering light and shadow in Photoshop. This is lesson number three where we take a look at shadow anatomy. Before we begin with analyzing different parts of a shadow, I wanna take a look at a workflow that I often see illustrators use when creating their own shadows within Photoshop or another Illustration program. So we've got this orange ball here that clearly has a light source off to the top right and a darker area to the bottom left. So, it's obvious that the shadow of this ball, if it's sitting on a flat surface, is gonna be extending out to the bottom left here. So, often what I'll see designers do is use a selection tool, to maybe generate a selection just like the same shape of the object. In this case, it's clearly roundish enough and then fill this layer with black and then use the free transform tool to just scale the shape down to create a shadow like that. Sometimes they'll even say well that's clearly not how it's supposed to be because it's clearly now not directly underneath it. So maybe move it off to the side, maybe scale it out a little bit and if they're savvy about it they might even use a distortion knowing that the shadow is going to be scaled out some. And often times people think, well that edge is too sharp so we're gonna need to blur that. I'll go Filter > Blur, zoom, blur and you might even think, well it should fade out a little bit. Cuz shadows tend to fade as they get further away from their object. So we would add a mask to it and use our gradient tool to fade out that shadow a little bit. And we think, hey that doesn't look so bad. That might actually look pretty good. This can work depending on the type of illustration that you're using. If you're creating an illustration that's more stylistic or maybe it's cartoonish this actually isn't all that bad. It's clearly a shadow, it's somewhat realistic in that it's believable and you didn't spend a whole lot of time analyzing it. And if it's like a background element then it's all fine and good. But if we really want to create convincing, realistic shadows, things have to be a little bit different. Now I'm going to reveal the actual shadow from this photograph. Look at the differences. So right away, it becomes apparent that there are several properties of this real photographed shadow that's much different from our illustrated one. One is the shape and direction. This isn't quite the same ellipse shape that we drew over here. It's coming out in almost an egg shape as it's sort of fanning away from that ball. Okay, the blurring effect, gets more drastic the further away from the ball it gets. And the fade out has a very distinctive shape to it. There's an inner shadow here that we're not capturing over here. Plus the color, the color is completely wrong. This shadow is too cool, as we would say. It's got too much blueish tint even though it's gray, it's not carrying the warm orange tones from the reflected light of this ball. So this is wrong in both shape, direction, size, and color. Let's go about analysing what we can figure out about the light source by looking closely at this shadow in relation to the object. You'll notice that we do have an inner, tighter shadow here that we talked about last lesson in this outer edge of the shadow, as well, because the shadow fades out and we know that that ends up being a result of the size of the light source. And we can trace this back if we go to the edge of the dark shadow. Draw a straight line up to about where we would think the edge of that ball is that's casting that shadow, likewise with the other edge. So the outerbounds of this fade out will connect that to the same point and see how those two lines come out to form a certain depth. I've also got two other lines here too. Because we talked before about how that light is probably a lamp that has a 3D depth to it. And we see the softness of the shadow on this edge here which would be a result of that depth of light hitting this closest rounded edge of this ball. And so we would use that same technique. Go from this very dark shadow edge to about where would expect that close edge to us and carry that though and likewise the edge of the faded shadow through that same point to help generate an idea of location and size of this light source. And its about there, and really that technique is one of the best ways of determining the proper location of shadows when it comes to illustrations and compositing. Once you can figure out the object in relation to its light source and the surface that the shadow is being cast onto. You can really figure out all those angles together and make thing just lock into place. Now let's take a look at the different elements of this light and shadow and this is really the anatomy portion of this. First of all, let's separate this into three distinctive elements. There's the cast shadow which is the shadow that's on this tabletop being cast by the ball. Which means it's the area that the light is being prevented from reaching this tabletop because the ball is obstructing it. Then on one side of the ball that's closest to the light source. We'll refer to this as the full light, that's the side that the light is absolutely seen. And then the other side of that is the core shadow. Two different sides of this ball, the side that the light reaches and the side that the light doesn't, at least not directly. Then, each of these three different basic elements can be broken down further. Let's start with the cast shadow. Within this cast shadow, you can see two different types of shadow within here. There's the shadow we talked about before that is directly underneath the ball and where every portion of the shadow is fully obscured from every portion of that light. So none of those beams or rays from that light source can directly hit this area because it's completely obstructed by this object. We'll refer to that as the umbra. That's that central area that is nice and dark. Then outside of that area Is this fall off area that goes from being partially shadowed to no shadows at all. And that is the more familiar term of penumbra, both of those elements together create the cast shadow in its entirety. So then let's take a look at this ball. Remember we have this separated into two distinct development. There is the full light, there is the core shadow. Now this area directly between the two is what we refer to as the terminator. That's the point where the light changes over, it sort of creates this imaginary line, between the light and the shadow. You can actually see that, sometimes it's nice and sharp, depending on the object. Sometimes it's very wide and soft. Then within that core shadow area is a sub area called the reflected light. Now, if you pay attention to the actual shadow of this ball, you see there's a lighter area just along this outside edge. That's the reflected light area and what's happening here is that these light rays coming from this light source are bouncing off the table and illuminating this lower area of the shadow. So, you can actually see a little bit of brightness within the core shadow and that's all that is, is light bouncing off the table and giving a little bit of illumination to this object in that area. Now, this also carries with it the color of the table, which is what causes a bit of reflection there, too. So, if the table were a certain color you would see that within the reflected light area. Let's move onto the light portion of the object. Now technically this is not broken down into sub elements of the full light section because the next portion of it is the half light. And what that means is it's that area where the light transitions from full light to the terminator. So remember there's the terminator line. In the full light area is the fully lit portion of the object but then as the light fades off, as it approaches this imaginary line, that's what we refer to as the half light area. And again, that's not technically a portion of the full light area, but it is within the lighted side of the object. And then we have the specular highlight. Now sometimes this is just called a Highlight, sometimes it's just called a Specular. And what this really is, is a reflection of that light source. Sometimes, the Specular Highlight can be very misleading. The general thought process is that it's located on the portion of the ball that's closest to the light source and that's not actually correct. Because the Specular Highlight does move according to the viewpoint that you're at. Now if we were to move ourselves over to the other side of this ball, we would see the specular highlight kinda ride across the edge and relocate itself. That sounds very strange but it's absolutely true. Whereas the shadow won't move because the shadow does not depend on where the viewpoint of the person is. It depends on where the object is in relation to the light source. But the Specular Highlight because it's a reflection and not a shadow will move around. If you think of it as a curved mirror surface, you know as you move yourself around the object, you're going to see a different reflection. That's why the Specular Highlight can be so misleading. Quick review, every object is separated into basically three main elements. There's the light, We'll talk about the full light as the portion that's closest to the light source and receiving the full amount of direct lighting. The half light is the portion of the light side that approaches this imaginary line known as the terminator which is where the light turns into shadow. The specular highlight is the portion of the light side that contains the reflection of the light source and is also the brightest portion of the image. The core shadow is the basic area of the object that is not receiving direct light. The reflected light is within the core shadow but is lighter because it's receiving light that's bouncing off the tabletop. The cast shadow is the shadow underneath the object that is being obscured from receiving direct lighting. Off the cast shadow, the umbra is the portion that receives no light at all because it's being completely obscured. The penumbra is the soft area of the shadow that only receives a portion of the light raise coming from the source. And that brings our lesson on shadow anatomy to a close. Now understanding the way that light works in relation with the object with the reflections, reflected light, and the shadows is critical for creating convincing and realistic shadows and lit surfaces within your own artwork. Our next lesson, Lesson 4 is on digital shadows where we talk about what's involved in creating a realistic cast shadow in Photoshop.

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