3D Lights – Shapes

I’m going to do a series on the technical bits of lights in 3D software. I plan to cover the following topics…

  • Light Shapes
  • Casting Shadows
  • Light Control and Colors
  • Advanced Topics

This series will be interspersed with other stuff; so no guarantees on the timeframe.

Point Lights

A point light casts light in all directions (like a sphere) from a single point in space. A bare light bulb or the light from a candle is a good real world example. Depending on the software you’re using, point lights may have limited use. For instance in DAZ Studio, the default point light casts a fairly weak light. It doesn’t reach very far at all. And because of the way that shadows work in 3Delight, it doesn’t do well with Deep Shadow Maps either.

Spotlights

Spotlights are kind of like flashlights or theater lights. Like point lights, they emit their light from a single point in 3D space, however unlike point lights, that light has a specific direction. The light spreads from the point of origin along the direction that the light is pointing in a cone shape.

In the basic spotlight for DAZ Studio, we can adjust the spread of that cone, allowing us to control how much of the 3D scene the light affects. In more advanced lights, you may also be able to control things like falloff (how far does the light reach) or apply gels and gobos to the light for special effects.

Spotlights are much more controllable and flexible than point lights. In most scene lighting (especially indoors), Spotlights are going to be your primary source of light.

Distant Lights

Distant lights simulate light cast from a very far source. The Sun and Moon are two such distant light sources which are typically simulated using distant lights. Unlike point and spot lights, distant lights do not have a point of origin in 3D space. The object that you see in the 3D viewport is to help you visualize the angle that the light is pointing. It does not represent where the light “starts”. The control for the distant light could be located underground, but as long as the angle of the light says that it shines on the objects in your scene, it will still light the scene.

In DAZ Studio, distant lights are typically used to simulate the sun, sky or moon. They are also used sometimes by new artists because they are easier to manage, you only have to worry about the angle that it’s shining. However because they light everything in the scene that they can shine on, they are not nearly as flexible as spotlights. Also, because of a limitation of the implementation of Deep Shadow maps, you may have some issues getting shadows to look exactly right using them.

Advanced “Shapes”

There are a couple of other lights that are worth mentioning here before we move on from shapes. These lights are different from the ones I talked about above in technical details of how they interact with the rendering engine, but since they do emit light into your scene, I wanted to mention them.

Area Lights

Technically, an “area light” (aka “mesh light”) isn’t a light in the same way that the others are. Instead an area light is a surface shader which emits light. Using such a shader allows you to make any object in your scene emit light from its surface. These sorts of lights can cast very pleasant consistent light across objects in your scene. In the real world, this is similar to the “umbrellas” and “light boxes” that photographers use. The drawback in 3D rendering is that typically they take longer to render as light rays are emitted from several locations on the object surface.

Ambient / Environment Lights

Ambient (or Environment) lights give the artist greater control over the ambient light in a scene. Most rendering engines have a built in ambient() function which returns a global value for ambient light in the scene. These sorts of lights (for example uberEnvironment which is provided in DAZ Studio) give the artist the ability to control how that light is calculated. They are very useful for simulating the indirect light that bounces around the real world.

Things to Come

My next topic in this series will be on casting shadows as this is typically an area that many artists struggle with getting to look just right.

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