wrong luminance calculation
Posted: Thu Nov 12, 2020 7:47 am
Hello all,
This is the test condition:
A light emitting surface with edge length of 1mm x 1mm emits 1 lm of light in an lambertian way.
This is observed by a camera very far away (infinte) normal to the light surface.
Theory says:
luminance = luminous flux / solid angle / projected lit up area
luminance = 1 lm / pi (solid angle of lambert emitter) / 0,000001 m^2
luminance = 318310 cd/m^2
Luxcore result is 172966 cd/m² read from Blender... I validated that with a professional software that reads *.exr files. It gives the same numbers as Blender.
A simulation with that software confirms the theoretical solution.
This is my test file: Please let me know your thoughts about that.
Thank you.
This is the test condition:
A light emitting surface with edge length of 1mm x 1mm emits 1 lm of light in an lambertian way.
This is observed by a camera very far away (infinte) normal to the light surface.
Theory says:
luminance = luminous flux / solid angle / projected lit up area
luminance = 1 lm / pi (solid angle of lambert emitter) / 0,000001 m^2
luminance = 318310 cd/m^2
Luxcore result is 172966 cd/m² read from Blender... I validated that with a professional software that reads *.exr files. It gives the same numbers as Blender.
A simulation with that software confirms the theoretical solution.
This is my test file: Please let me know your thoughts about that.
Thank you.