Variable: SH_DC_TO_IRRADIANCE

const SH_DC_TO_IRRADIANCE: 0.886227 = 0.886227;

Defined in: threejs-environment/src/light-estimate.ts:41

The L0 band of a spherical-harmonic probe, scaled to irradiance.

0.886227 is Y00 * PI - the constant that turns the DC coefficient of a real-valued SH basis into the average light arriving from every direction, which is exactly what an ambient light is.