Even the best 3D scenes are ruined by ill-applied lighting. Gaining a deep understanding of how to set up and control your lights is key to creating interesting (and convincing) CG lighting.
In this guide, we are walking you through the basics of lighting a 3D scene with CG lighting and dishing out pointers to improve your light skills.
Want to learn more? Read on!
#1: Start with total darkness
Light is nothing without darkness. Or put another way, without light, you couldn’t see much.
One of the most common mistakes that artists make is that they work with the light without much thought about the shadows.
You see, if you want to make your lighting as realistic as possible then you have to be well versed in the intricate relationship between light and shadows. You have to embrace the darkness to be in control of your scene’s lighting.
So before you work with the lighting, start with total darkness.
Total darkness is next to impossible in real life because some forms of natural light always make their way into an environment, no matter how dim the said environment is.
But using a computer graphics software, it’s possible to start in total darkness. To do this, just disable any other light in the scene – such as ambient light or default lighting – then gradually add all the light that will appear in a scene.
#2: Offsetting the effects of ambience to add depth and shading
Ambient light is the average volume of light that’s generated by emissions of light from other light sources that surround a lit area. Essentially, ambient light is a type of indirect light that has bounced off on objects in a scene.
Working with ambient light is quite tricky because it could 1) impair your control over the lighting of a scene and 2) it could produce an unrealistic effect when applied improperly.
The ambient light functionality varies from program to program. However, apps that come with radiosity or other global illumination models could produce a more precise calculation and application of ambient light instead of producing a uniform light.
Depending on the amount of illumination that bounces into an environment, a shadowed room is often illuminated slightly by ambient light in real life.
Real-life ambient light is slightly tinted as it bounces around an environment. The tinted light adds the color it has picked up from the environment to the different sides of an object. The intensity of the bounced off light varies in intensity too, some are dimmer on certain sides of the objects. Different tones are also added to the object from different angles.
Working with ambient light using a computer program involves careful calculations because the ambient light produced by a 3D graphics software behaves differently from real-life ambient light.
Most programs produce a flat, uniform brightness that makes objects visible even if there is no light source that’s illuminating them.
In addition, the illumination applies the same color and intensity to all sides of the object regardless of the position. All these rob your scene of variety, depth, and richness. To achieve realism to your CG imagery, you have to apply the appropriate tone and calculate the right direction of indirect light.
To take control of the lighting, turn off the global ambience in the scene and then choose a color for your global ambience. Opt for black so no light is added to the scene other than the light sources that you will set and control.
Turning off the global ambience presents a full range of tones that you could apply to light your scenes and the range of tones is only limited by the latitude of tones available on the film stock.
Some artists tend to apply uniform global ambience despite the unreal illumination because they are afraid that certain areas of the scene would become too dark without it. Thankfully, there are strategies that could add secondary light to quality-oriented renderings.
#3: Working with point lights
Point lights are crucial for lighting a 3D scene.
Also known as omnidirectional lights, point lights are light sources that produce a uniform beam of light. The illumination is scattered in all directions, like a single bulb in a room or a lone star in the night sky. This type of light source is a staple in 3D graphics programs but the fact is, light does not behave like this in real life.
Real-life sources of light do not produce illumination in a uniformly omnidirectional way. The level of illumination will always be stronger in some areas than others.
To illustrate, a real light bulb does not produce light in a uniform way because the metal socket tends to block light from one direction. In addition, most light bulbs are attached in a fixture of some kind or even diffused with a shade, which affects the direction of the illumination. All these will be taken into account to achieve realism.
If you are working with point lights, you can simulate the uneven distribution of light by giving a throw-pattern by applying a texture map to the light or by setting the light with 3D objects that cast shadows. This way, the direction of light being cast by the point light will be uneven.
#4: Working with spotlights
A spotlight is quite similar to a point light; it generates a strong beam of light. But unlike a point light, a spot light’s light is not scattered around, it is focused in a single direction. Spotlights are often used to aim the light at a specific object or subject in CG imagery. Thankfully, a spotlight is easy to control because the functionality comes with options and settings that cannot be found in other light types.
The rotation of a spotlight could define where the light is being aimed at. You could also select a specific target so that the light is always positioned towards the direction of the said target.
Grouping a spotlight with a 3D object is also a great way to highlight the said object with a concentrated beam of light. This technique lends a beautiful glow of illumination, as if light is emanating from the 3D object.
With spotlights, you get control over the width of the cone; the illumination could be a broad beam of light or a narrow beam of light. The spotlight’s cone can be adjusted via the spread or falloff. These settings diffuse the edges of the light beam so that the direction of the light is less stark.
If say, you’d like to aim a spotlight within a room to illuminate the area near the windows or curtains, you could soften the beam of light to make the illumination as realistic as possible. And to darken the corners of the room, you could aim a spotlight with negative brightness.
Unlike some lights, spotlights are so easy to control that they’re often used to mimic light from almost any source. Most artists also light their scenes using spotlights and not much else. And if the light has to be scattered in different directions, some would simply add several spotlights to recreate this effect. Nothing wrong with this technique but to achieve different light effects and fine-tune your skills as a light artist, do grow your repertoire.
#5: Working with directional lights
Ok, we’ve come to our 5th tip for lighting 3D scenes.
A directional light is a distant source of light that hits every object in a scene from the same angle regardless of the objects’ position. The farther the light is from the subject being lit, the more parallel the illumination and shadows of the objects will be. The shadows that are cast by objects lit by a directional light will be cast in the same direction of each object’s shape.
When it comes to setting the directional light, the location of the light relative to the objects being lit does not matter. What’s important is the direction of the directional light itself. Controlling the angle of the directional light will vary from program to program. Some apps use the rotation of an icon to adjust the direction of the directional light while others use a vector from the icon to the target or the global origin. Depending on the software you’re using, the directional light could also mimic the sun’s angle based on a specific time, location, even date!
Directional light is not as simple to set to a specific spot compared to a spotlight or a point light. This is why directional lights are often used as a secondary light or fill light, not the main source of light in CG imagery.
Directional lights illuminate a wide expanse of space and the light itself could be atmospheric or ambient, which make directional lights an ideal alternative to global ambience.
You can use a set of directional lights that are positioned from different angles to produce fill light.
#6: Working with area lights
Unlike directional light in which the light touches different objects in a scene, an area light produces light within a set size, shape, or boundary. This type of light source creates shadows with soft edges, adding realism to your renders.
Because area lights have a definable scale, the rays of light are not emitted from the exact same point and the result is a more accurate simulation of real light. When the light is scaled small, the illumination will be similar to a point light. If the scale is bigger, the illumination covers a wider expanse of space but the light produces soft shadows and illumination that wraps around nearby objects or subjects.
This type of light source enhances the realism of the scene but applying it will extend the rendering time. If you are pressed for time, you can save the area lights for rendering high-quality stills as opposed to long animation projects with a set deadline.
Area lights are categorized into three types, spherical area lights, flat area lights, and linear lights:
Spherical area lights
A spherical area light imitates the light that’s coming from a spherical region of space, such as a glowing light bulb. A spherical light can be evenly omnidirectional, which means the rotation of the light won’t have any effect on your output. This type of area light is often used to light objects or subjects that are close to a large light source. It is also used as a sub for a point light on scenes where the light has to look diffused or when you want the light to produce soft shadows. Spherical area lights are scalable in three dimensions.
Flat area lights
These area lights come in discs, rectangles, and other flat shapes. The light that flat area lights produce is naturally diffused or soft. The illumination mimics the light that ceiling panels produce. Flat area lights are often used to simulate the reflected light from brightly lit ceilings and walls, giving the scene a soft, realistic illumination in still-life renderings as well as portraits. Flat area lights are scalable in two dimensions.
This area light imitates the illumination produced by laser blasts, fluorescent tubes and other lines of light. Compared to spherical or flat area lights, linear lights render quickly because it only needs to be sampled along one axis instead of two or three.
Depending on the software you’re using, lines of light – such as a neon sign – could be used as a true light source. But such an effect is usually produced by rendering a bright-looking object and setting some other type of light source near the site to light the surrounding areas. The bulk of your work as a light artist involves adjustments and revisions.
Over to you!
There you have it! Now you know all about how to light a 3D scene and set up and control your lighting.
Fine-tuning your light skills is important in your journey as a top digital artist and that’s why we highly recommend signing up for our online light courses.
Now, we’d love to hear from you:
What is your #1 question when it comes to lighting a 3D scene?