Atmospheric effects (scattering, volumetric light, caustics through water and glass)

Painting how light moves through air, fog, water, and glass so that beams, haze, and caustic patterns feel physically believable.

Track it on the checklist

What it is

Light doesn't travel through a vacuum: it bounces off particles in the air (dust, moisture, smoke), gets filtered by fog, and bends and focuses through transparent materials like water and glass. In practice, this means painting beams of light, hazy distance, god rays, glowing fog, and the dancing bright patterns at the bottom of a pool or under glass.

For scattering in air or fog, the space itself carries a faint value and sometimes a hint of color. Strong light becomes visible as soft cones or shafts where particles catch it. Distant objects lose contrast, shift toward the sky color, and soften at the edges. Backlit dust, mist, rain, or smoke glows where light cuts through it, while silhouettes in front of it stay darker and sharper.

For volumetric light, treat light as a 3D shape: a beam from a window, a flashlight cone, sunlight through trees. Decide how thick the medium is (clean air vs. heavy fog), then paint the beam brighter where it's aimed straight at you and fading as it travels. Always respect occlusion: anything in front of the beam interrupts it and casts a softer shadow into the haze.

For caustics, light concentrates after passing through or bouncing off curved transparent or reflective surfaces. Water surfaces create broken, animated patches of brighter light on pool floors, rocks, and characters. Clear glass or liquids cast warped bright shapes on the table beside them. These patterns are sharpest and highest-contrast where light is strongly focused, and follow the form of the surface they land on, not just the outline of the object casting them.

Why it matters

Without these effects, scenes feel like miniatures in perfectly clear air: distances are too crisp, interiors show no dust or haze, and water and glass sit on top of the scene instead of bending its light. Depth collapses because far elements just get smaller, not more veiled; strong light feels weak because it never touches the space around it; underwater or rainy scenes read like dry scenes painted blue. Handle scattering, volumetric light, and caustics, and you can show the thickness of air, the wetness of a place, and the weight of light itself — essential for believable environments, cinematic lighting, and any mood built on weather or water.

You can check it when

✓You can paint atmospheric perspective in a landscape — fog, haze, or thick air — so distant forms lose contrast, saturation, and edge sharpness in a controlled way.
✓You can paint a visible light beam (through a window, trees, or a flashlight) that respects occlusion — objects in front of it interrupt or soften it instead of letting light pass through unaffected.
✓You can paint an underwater or rainy scene where light feels filtered by the medium — colors shift, contrast drops, and highlights and shadows behave differently than in dry air.
✓You can invent or refine caustic patterns from water or glass that follow the surface they land on and feel brighter and crisper than the surrounding light, instead of being random stripes or stickers.

Atmospheric effects (scattering, volumetric light, caustics through water and glass)

What it is

Why it matters

You can check it when

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