Data describing the estimated lighting environment in all directions.
- iOS 11.0+
Spherical harmonics provide a compact mathematical model for the global lighting environment around a point in space, describing the distribution and colors of multiple directional light sources. When used in a renderer that supports environment-based lighting, spherical harmonics provide much less high-frequency detail than a cube map texture, but make much more efficient use of GPU resources.
ARKit provides second-level spherical harmonics in separate red, green, and blue data planes. Thus, this data buffer contains 3 sets of 9 coefficients, or a total of 27 values of 32-bit floating point type.