Lighting simulation is as accurate as never before with full spectral resolution and support for ior and scattering data. Besides the scalar values of refraction index, user may also select a coefficient file that contains measured values of index of refraction (n) and extinction coefficient (k) over the spectrum. Using these measured data, we can have accurate reproduction of the corresponding materials.

Custom Fresnel curve gives the ability to create certain categories of materials that present a "flat" look, like velvet and satin. The user can override the internal interpolation between normal reflectance (seeing the surface perpendicularly) and grazing reflectance (seeing the surface at grazing angle) with his custom curve. The editing of Fresnel curve is not only fun but it is also more powerful than other rendering solutions, since here we can change the complete curve from 0 to 90 degrees, make use of presets and save/restore custom curves for later reuse.

Concerning lights, Thea Render can handle more complex emission models by making use of an IES file, describing light emission according to measured goniometric data. Similarly, for volumetric scattering, absorption and scattering spectral coefficient files can be used.