Custom emitter based on known irradiance spectrum

[lcit]

I am trying to implement a custom emitter that generates a known measured irradiance spectrum (W/m2/nm). So far my approach is the following:

1. use the irregular spectrum object to store the known values-wavelengths pairs

Properties props;
props.set_plugin_name("irregular");
props.set_string("wavelengths", wavelengths);
props.set_string("values", values);
m_intensity = PluginManager::instance()->create_object<Texture>(props);

2. modify sample_direction(.) function as follow.

UnpolarizedSpectrum spec = m_intensity->eval(si, active);
return { ds, depolarizer<Spectrum>(spec) };

Is it true that this formulation would produce the same irradiance spectrum on the scene admitting the emitter is positioned at the correct distance?
Ps: Pardon if the terminology is not correct, I do not have much background in PBR.

[njroussel]

Hi @lcit

Yes, that seems correct. Keep in mind that Mitsuba is unitless, the world-coordinate system is not explicitly meant to be in meters. Depending on where you've gathered your assets from you might need to scale them to be coherent with your measured irradiance.