Reflectivity at glancing angles (Fresnel effect)
Surfaces reflect more light when you view them at a glancing angle than head-on. Paint that stronger edge reflection so materials feel solid.
What it is
Reflectivity at glancing angles — the Fresnel effect — means surfaces reflect more light the more you look along them instead of straight at them. A lake looks darkest right below you and turns into a bright mirror toward the horizon; a glossy table reflects more along its far edge than in the middle.
In practice, this shows up as bright bands near silhouettes and edges turning away from you, even on materials that otherwise look dull. Plastic, varnished wood, car paint, wet skin, and even eyes pick up stronger highlights and reflections toward their edges.
So don't spread reflection strength evenly across an object. Keep front-facing areas about local color and soft shading; as the surface turns away, push value contrast and specular color instead. On glossy objects this becomes a full mirror-like band; on semi-matte ones it's just a gentle lift near the edge.
Why it matters
Without this, materials feel flat and airless — reflections get pasted on wherever they "look cool" instead of following the viewing angle, so spheres look like stickers, armor looks like plastic, and eyes feel dead. Silhouettes stop catching light, and objects stop sitting in their environment. Respect edge reflectivity and even simple shapes gain weight, curvature, and a sense of real light bouncing off them.
You can check it when
- ✓You can point to the edges in your work and see stronger reflections or value lifts where the surface turns away — not highlights placed at random.
- ✓You can repaint the same glossy object from a new camera angle and have the reflection shift correctly, while the light direction stays the same.
- ✓Your metal, plastic, and wet materials read more reflective at silhouettes than on front-facing planes, even when you simplify or stylize other details.
- ✓In photo studies, you can tell where reflection dominates (glancing angles) from where local color and shading dominate (front-facing areas).