Illumination Best Practices

Light direction is the angle that the source of light comes from in relation to objects. The same object lit from different directions can look absolutely different and bring out different emotions. For example, a face lit up from the bottom seems dramatic and even intimidating. By changing the light direction, you can highlight the object, enhance the illusion of depth, and intensify details that you find essential.

The light intensity defines the amount of source light emitting on the object. Adjusting the value, you can either show objects on the scene, highlight or hide them from viewers' eyes. Intense light rays bring out strong features, add contrast to the composition, and make the whole picture look vibrant. Subtle lighting, on the other hand, softens the edges and reduces the tension. 

In reality, we can see and recognize objects due to the light rays hitting them from different directions and intensities and painting them with highlights and shadows. Does the light color play a role in 3D modeling? For sure! Designing a winter landscape scene, you'd probably choose the blue tint, while for a summer evening, you'd likely stick with warm yellow and orange. Another thing to remember is that objects in the distance tend to be less saturated and darker than those in the foreground.

The size of a light source can bring a significant difference to the scene. A small-sized light source casts distinct shadows and may bring in more dramatic or mysterious moods — think of torchlight in a dark cave or lighting bugs in the woods. On the other side, light sources occupying a larger area cast more subtle and warm shadows.

You may spend hours polishing off the models and scene composition, but all work can go down the drain without proper lighting. Fake lighting contradicts the physics laws and can give a completely different feeling to your artwork. However, sometimes, going against the rules helps create mesmerizing non-realistic lighting for a scene. 3D artists may deliberately swear by fake lighting techniques that use artificial colors, the ones you don't meet in nature, or illuminate objects against all physics laws.

The lighting stage of 3D modeling is about reproducing the light properties we meet in the real world — realistic lighting. To make it right, 3D designers use the Cornel box.^[1] It's a well-known method developed at Cornell University that 3D artists use to determine how accurately their computers render the lighting. With all the specific properties and specifications, such as the source of light direction and intensity, the colors of walls, objects' textures, and their position in the room, the method compares the outcome image with an actual photograph of the same scene.

There's no light without darkness, and they usually work in tandem, affecting users in different ways. Designing a scene, keep in mind the light psychology behind each technique. Some lighting can carry positive feelings and bring joy and happiness. However, by playing around with light intensity, direction, and the size of the source light, you can bring out a dramatic feeling or define the sadness of the moment.

The direction of light can change the scene dramatically, and the bottom-to-top lighting proves it. This type of lighting is a good fit for campfire horror stories or dramatic scenes as it makes villains look even more powerful and fearsome and fills the surroundings with dark shadows.

Top-to-bottom lighting is the most natural as it imitates a natural direction of light: the sun's light direction, street lamps, overhead lights in an apartment or office, etc. This light direction creates the most flattering highlights and shadows. However, top-to-bottom lighting can have a harsh and powerful effect and cast some divine and noble energy on the character. Consider this when lighting characters and want to bring out or enhance their personalities. 

The key light indeed plays a crucial role in the lighting setup of a scene. It's the primary and the brightest light, and its purpose is to illuminate the most important objects and draw viewers' eyes to them. The key light should not necessarily follow the subject at a stretch — it may shine on it through tree leaves, the crowd of people, and other obstacles.^[2]

The three-point lighting setup is the most traditional method that contains three types of lights — key light, fill light, and backlight. The key light is the primary one and creates the mood of the scene. The fill lights fill in the shadows that the key light produces, taking care of details in the darkness. The backlight is also called a "hair light" as it comes from behind and points at the character's neck.^[3]

A proper lighting setup helps control shadows and show the best or worst of subjects.