Lighting Reference: Complete Guide & Methodology

This guide shows how to get accurate, repeatable lighting studies with the Light Reference Generator. You’ll learn the interface, the underlying logic, and practical example setups—plus tips to turn studies into better art.

Quick Start

  1. Pick a shape: Sphere (gradients), Cube (planes), Cylinder (bands/rims). Use the Presets dropdown to jump to a starting setup (e.g., 3/4 Key).
  2. Aim the light with Azimuth (horizontal) and Elevation (vertical). Try Az 45°, El 30°.
  3. Refine with Light Distance (in/out), Beam Angle (narrow↔wide), and Softness (hard↔soft shadows).
  4. Use Fill Level to lift shadows. Toggle Auto-Compensate for Distance to keep brightness comparable while you move the light.
  5. Fullscreen for a larger viewport, Copy Link to share exact settings, and Download PNG to export.
Light Reference UI with canvas, presets dropdown, and light controls
Tip: If the subject seems to “disappear” as you pull the light back, enable Auto-Compensate for Distance or widen the Beam Angle.

Methodology (How it Works)

The scene uses a SpotLight aimed at the origin plus a small ambient/hemisphere fill for readability. You place the light with Azimuth and Elevation, then control character with Light Distance, Beam Angle, and Softness. Shading is based on surface normals of the primitives (sphere, cube, cylinder).

Assumptions

  • Single key light (SpotLight) with controllable angle (beam width) and penumbra (softness).
  • Optional Auto-Compensate scales intensity ~ inverse-square to keep subject brightness more comparable as Distance changes.
  • Ambient + hemisphere Fill Level lifts shadows uniformly; GI/SSS/roughness maps are not simulated.
  • Camera is fixed; shapes can be moved (POSX/Y/Z) and rotated (ROTX/Y/Z in radians).

Simplified Pipeline

// Degrees → radians
az = deg2rad(azimuth)
el = deg2rad(elevation)

// Light position on a sphere of radius r (Distance)
Lpos = [
  r * cos(el) * sin(az),
  r * sin(el),
  r * cos(el) * cos(az)
]

// Spot setup
spot.angle   = deg2rad(beamAngle)   // spread
spot.penumbra = (softness == "soft") ? 1.0 : 0.0
spot.intensity = baseIntensity * (autoComp ? (r / r_ref)^2 : 1.0)

// Shading (conceptual)
diffuse  = max(dot(n, normalize(Lpos - P)), 0.0)
specular = pow(max(dot(reflect(-Ldir, n), V), 0.0), shininess)
color    = baseColor * (ambient + fill + diffuse * I) + specularTerm
Light Vector (L), Surface Normal (N), and Angle θNL (from light)V (to camera)θSurface pointN: Surface normalL: Light vectorθ: Angle between N and L

What This Means for Artists

  • Beam Angle sets highlight size & spread; Softness sets shadow edge quality.
  • Increasing Distance gives more parallel rays and gentler falloff across the object (but also lower illuminance unless compensated).
  • Fill Level controls global contrast without moving the key.
Limitations: The tool favors visual intuition over strict photometry; treat intensity as a relative study control.

Example Studies

A) Classic 3/4 Portrait (Hard)

Preset: 3/4 Key (Hard) — Az 45°, El 30°, Dist 6, Beam 35°, Softness Hard, Fill 0.20.

3/4 hard light with distinct terminator and specular

B) 3/4 Portrait (Soft)

Preset: 3/4 Key (Soft) — same az/el, Dist 4, Beam 60°, Softness Soft, Fill 0.30.

3/4 soft light with broader penumbra and gentle specular

C) Rim Back

Preset: Rim Back — Az 150°, El 25°, Beam 20°, Fill 0.10. Clear edge separation; keep fill low for contrast.

Back/rim setup creating edge separation

D) Beauty Soft

Preset: Beauty Soft — Az 0°, El 60°, Dist 4, Beam 70°, Softness Soft, Fill 0.50.

Soft, flattering lighting with high fill

Tips for Artists

  • Use Presets as a base, then tweak Distance/Beam/ Softness to taste.
  • Study edges: Softness + Beam shape the penumbra; Distance affects falloff feel across the form.
  • Compare systematically: Toggle Auto-Compensate on/off while changing Distance to feel exposure vs. falloff differences.
  • Annotate downloads: Write az/el/dist/beam/soft on the PNG corner; keep a series by varying one control at a time.
  • Accessibility: All sliders are keyboard operable; labels and aria-label aid screen readers.

FAQ

What does Auto-Compensate for Distance do?

It boosts the key light’s intensity roughly by the square of the distance so the subject remains similarly bright as you move the light away, while still changing falloff and shadow character.

Are the values physically exact?

No. The tool is designed for visual intuition and repeatable studies rather than photometric accuracy.

How do I share an exact setup?

Click Copy Link. The URL encodes your settings (az/el/dist/beam/soft/fill/preset/shape/grid).

Changelog

  • 10/18/2026: Upgraded guide for SpotLight, Distance, Beam Angle, Softness, Fill Level, Presets dropdown, shape rotation, Fullscreen, Copy Link.