Physically based units

[codeonwort]

Physically based lighting needs physically based units and measurements.

World distance unit

• is now meter. (https://github.com/codeonwort/pathosengine/pull/41)

Photometric light units

• Illuminance (lux) for Sun
• Luminous intensity (candela) for local lights

References: Physical Units

• https://seblagarde.files.wordpress.com/2015/07/course_notes_moving_frostbite_to_pbr_v32.pdf
• https://www.activision.com/cdn/research/Real_World_Measurements_for_Call_of_Duty_Advanced_Warfare.pdf
• https://mynameismjp.wordpress.com/2015/04/04/mitsuba-quick-start-guide/
• https://physicallybased.info/
• https://ikrima.dev/graphics/physical-units-for-lights/
• https://dev.epicgames.com/documentation/en-us/unreal-engine/using-physical-lighting-units-in-unreal-engine?application_version=5.0

References: Exposure

• https://placeholderart.wordpress.com/2014/11/16/implementing-a-physically-based-camera-understanding-exposure/
• https://dev.epicgames.com/documentation/en-us/unreal-engine/auto-exposure-in-unreal-engine
• https://bruop.github.io/exposure/
• https://www.alextardif.com/HistogramLuminance.html

References: Real-world Sun Position

• https://github.com/cosinekitty/astronomy
• https://stjarnhimlen.se/comp/tutorial.html

[codeonwort]

Implement IES profile also, if possible

[codeonwort]

IES profile was not implemented. Later