In the realm of lighting design, you may encounter IES files. These text files contain numerical data representing the three-dimensional “shape” of a light fixture’s projection. Closely related to “beam spread,” or “beam angle,” an IES file captures the nuanced light output pattern emitted by a particular fixture. We’ll shed some light on how manufacturers capture this photometric data, and how designers use it.
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Special thanks to Puneet Sharma for the goniophotometer footage.