Blender Relief Tutorial: The Sun

Previous Chapter: The Camera

The final piece of our virtual photo studio is a light source. Its color, type, and position affects the scene’s lighting, and thus the final image.

Choose Light Type and Strength

Our default scene comes with a light in it already, which is represented by a couple of dashed-line circles with a dot in the middle.

Seen here selected in orange.

In the 3D Viewport or the Outliner, select the existing light. Then, click on the green lightbulb icon to look at our Object Data Properties.

Here we can specify a few things about our light source. Under the Lamp set of options, I see a number of different lighting types: Point, Sun, Spot, etc. Right now, Point is selected. This means that our light source is basically going to act like a light bulb, floating above our scene and casting light in all directions. We’ve also got options here for analogues of other real-life types of lights, like spotlights. For making shaded relief, though, we want to simulate the Sun, so choose that one. Notice that, in the 3D view, the now light has spikes coming out of it: it’s represented differently, to remind us that we’ve chosen a Sun-style light source.

A lightbulb near you will cast light rays in all directions. The Sun, on the other hand, is far enough away that the rays of light that reach Earth are practically parallel (at least, when considered over a modest-sized area). That’s what we’re telling Blender to simulate by choosing this option. It will flood the scene with light rays all coming from the same direction.

Rays.jpg

Light rays are pretty much parallel as they strike the Earth.

Before we leave this panel, let’s adjust the sun’s strength, which simply controls how bright the light source is. The higher the number, the brighter the sunlight and the lighter the relief. The default setting of 1000 is way too high for our purposes. If you do a test render, you’ll see what I mean.

Go ahead and turn that down to 5.

Set Sun Angle

The next thing to do is tell Blender what direction the light is coming from. And to do that, we need to go to a familiar place, the Object Properties. While the light is still selected, click on that orange square icon.

Now, when we went here for the plane and for the camera, we adjusted their positions. It turns out, though, that with a sun light, we don’t care where it sits on the stage. Blender ignores the lamp’s position entirely and simply hits every part of the scene with parallel light rays of equal intensity. The only thing it cares about on this panel is what angle to give the light. Notice how there’s now a line coming from the light in the 3D view: that’s the current direction of the light rays.

The current angle of the rays upon our plane.

We can change that by changing the lamp’s Rotation in the Object Properties. Enter 0 for X, 45 for Y, and 135 for Z. Notice how the ray line changes; now the light will hit the scene from a different angle. Have a look at how it’s turned out by rendering a new relief.

It’s looking much better now that we have the right sort of light source (though, as ever, there are still some things to adjust). Try changing the Y and Z numbers on the lamp’s rotation and doing renders to see what happens. The Z number controls what direction the light comes from. 135 means upper left. 225, on the other hand, means it comes from the lower left. As a general rule (for all shaded relief methods), light should come from the upper left of the scene, or the relief will start to look inverted.

This was with a 315° angle: light coming from the lower right. Many people will see this as inverted, or at least confusing.

Changing the Y number here will affect how high the Sun is in the sky. Notice how if you crank the Y up to 75, the dashed line in the 3D view shows that the light rays will be closer to parallel with the ground. That would simulate the Sun being lower in the sky, near dawn or dusk, with longer shadows.

Let’s keep things at 45° and 135° for the time being. You’ll probably have occasion to change the former much more often than the latter.

Sun Size

Now, go back to the Object Data Properties by clicking on the green light bulb icon. There’s one more thing to look at here, which is the Angle parameter. This is perhaps confusingly named, as it does not relate to the angle of the sun’s rays. Instead, it’s the sun’s angular diameter, which in real-world terms controls how soft the shadows are in our final render. Right now it’s set to 11.4°, which is quite small, giving us a very harsh relief that looks sort of like we’re on the Moon. Try setting the size to 90° instead, which will make the shadows much softer.


Feel free to play around with this setting and do test renders.

Sun angle 11.4 on the left and 90 on the right.

I generally keep this setting at 90, though if you were doing a Moon relief I suppose you might want to lower it.

There’s no need to change the color of the Sun here. It’s white, and that works fine for our greyscale relief. If you want to do relief in color, you might try messing around with this (and with the color of your plane material).

With that, our lighting is ready for the scene. We managed to

  1. change our light type to Sun,
  2. reduce its strength to something reasonable
  3. set it to the correct angle, and
  4. increase its angular diameter (i.e., softness).

Just a little bit more to do and we’re all set!

Next Chapter: Final Adjustments