Just like materials, some lights require the definition of spectrums. Measured spectrums range and number of channels can be overridden to reduce their memory size.

See the expert materials section for more details.

When the expert mode is enabled, environment using a skybox of type "RGB Panoramic" have an additional Gamma field. This value defines the gamma correction applied to the image.

By default, when the expert mode is not enabled, a gamma of 2.2 is used for textures of type *.hdr or *.exr, and a gamma of 1 is used for all other textures.

When the expert mode is enabled, you can choose to load the area lights of type "Display/Measured" faster but with some imprecisions.

Display measures contain spectral data sampled irregularly between 420nm and 698.5nm. Predict Engine requires data sampled regularly between these bounds. When the Fast Load option is enabled, the measure is considered to be already regularly sampled : the entire measure will be loaded but there can be some shifts on the actual wavelength corresponding to each value.

We recommand using this option for development only, to be able to reload the scene quickly when working on the scene content. If you want an accurate result, this option must be disabled.