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This course is part 3 in David's Digital Matte Painting Essentials series. Go back to Digital Matte Painting Essentials 2: Perspective, part 2, to recreate the castle drawing he uses in this course, or if you simply want to learn more about form, you can use the example provided in the exercise files.
- Selecting the silhouette
- Find the dark sides and light sides in the drawing
- Using mask-holding layers
- Examining the light and dark sides of rounded surfaces
- Looking at the cores
- Adding cast shadows
- Separating surfaces with final darks
- Adding ambient occlusion
Skill Level Beginner
The next property of light we want to talk about is cast shadows. What are cast shadows? Cast shadows occur when an object blocks the light that would otherwise be received by an object behind it. An obvious example on this castle is this doorway that projects out from the face of the castle. It is blocking the light that would otherwise be projected onto this wall behind it. Let's go ahead and add that cast shadow. Remember when we started this section, I asked you to draw in the angle of the sun for reference.
Here's where we're going to use that. Refer to the angle of the sun, and that is the angle that will be projected onto this wall. You can do a technically perfect projection of this shadow by plotting the exact position of the sun and using some fairly advanced perspective. However, most artists I know fake their cast shadows, and don't do a technical plot of them, and that's what we're going to do here. As long as you're consistent in the angle and length of your shadows faking them will give you a very convincing result.
So add a new layer and lets call it cast shadows. Set the layer to multiply since cast shadows will always be darker. Using the lasso tool, draw from the top of the doorway out using the angle of the sun you marked. And then straight down to show the side of the doorway. If I'd made the shadow longer, that would indicate that the sun was more behind the castle. If I'd made the shadow shorter, it would mean that the sun was more to the side of the castle.
Once we've laid down this one shadow we will try to match the depth of all the other shadows to this one, make sure you still have that medium gray loaded and fill the selection full of that tone. There are four properties of cast shadows you need to think about to make them as realistic as possible. The first property is the cast shadows almost always occur on the light side of objects, not on the dark side. For instance, this dark line where the shadow bleeds over onto the dark side is not realistic.
In landscapes cast shadows are created by the main light source, the sun in 99% of all exterior conditions. Why don't cast shadows occur from the reflected light? Because the fill light for the sun is the softest reflected light of all. I ask my students every semester to tell me what that giant reflector is. Pause this video a minute, and see if you can get it. The answer is the sky. The sky is the big reflector that the sun is bouncing off of.
And since the sky is so huge it doesn't cast shadows. There are some very rare exceptions to that rule. Like, your castle was built at the base of the white cliffs of Dover. But in almost all the instances landscapes will only have cast shadows from the main light source the sun. Shadows on the dark side will be much softer and we will deal with them in a later video. So lets get rid of that dark line were the cast shadow overlaps the dark side by loading the dark sides collection and to leading it from the cast shadow layer.
The second property of cast shadows you should think about, is that its unusual for them to be razor sharp, like this one I have from the doorway. You could have this sharp a shadow on a crystalline clear fine day with no clouds in the sky. But most of the time, shadows will be a little softer than this. Also, since we're faking the shadows rather than doing a technical plot, softening them can make it less obvious if you're a little bit off on your guess. Another property of soft cast shadows that I want you to be aware of, is that the further away a shadow gets from the surface that is projecting it.
The softer it will be, so I might leave my shadow very crisp right here where it starts, but as it gets further away from the door, softening it will be a good idea. So I'm going to add a bit of feather to my lasso tool and lasso around the far edge of the shadow and add a Gaussian blur of four pixels. That leaves the shadow sharp near the projecting surface and softens it a bit further out. The last property of cast shadows you should think about, is that they will be darkest near the object that is casting them.
And as the shadow gets farther away from the shadow casting object, they will get more reflected light, and be lighter. So I'm going to take a very soft eraser. And erase just a bit of the far edge of this shadow, lightening it. Let's do another cast shadow. This one from the bastion on the corner of the wall. Since this bastion sticks out about half as much as the doorway of the castle. The shadow will be about half as deep. I'm going to lasso around where the shadow would be.
This time with the lasso tool having a little feather on it to soften the edge of the shadow. Then fill it with medium grey. Load the dark side selection. Delete it. A bit of the cast shadow is spilling over onto the crenellations. So either hand select them or load the crenellations forms layer. Intersect with the bit you need and delete it to clean up the shadow. For your reference here's a chart of the four properties of cast shadows I talked about in this video.
Next up, we're going to explore a special kind of cast shadow, shape shadows.