Radiometry Foundations | Graphics Lectures

This lecture introduces radiometric quantities used in physically based rendering.

What this lecture covers

Why radiometry is the right language for light transport.
The relationship between flux, irradiance, and radiance.
How these quantities appear in rendering equations.

Derivation

Starting from flux $\Phi$ , irradiance over a differential area is: $E = d\Phi / dA$

For directional dependence, radiance is: $L = d²\Phi / (dA\,d\omega\,\cos\theta)$

Basic math test

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Inline math: $E = dΦ / dA$

Block math:

L = d²Φ / (dA · dω · cosθ)

If equations render correctly, KaTeX/MathJax is configured.

Code block test

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struct Ray {
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    vec3 origin;
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    vec3 direction;
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};
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vec3 trace(const Ray& ray) {
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    return vec3(0.0f);
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}

Image component examples

Radiometry diagram (single image block) — this is a caption

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