Hi Axel & all,
I had come across this, too. I have no further insight into this than what is published on the website, but this appears to be a rather ambitious approach bundling a 3D-description of luminaires (L3D) and an advanced photometric description (GLDF) of luminaires as well as sensors.
GLDF seams to go significantly beyond the known IES approach, e.g. with representions for spacial inhomogenity due to multiple light sources per luminaire, control, spectral power distributions and dimming.
L3D not only is based on OBJ, but also accounts for geometric constraints for the installation / aiming of luminaires. This may lead to some kind of parametric modelling of luminaires that would ensure that no impossible configurations are modelled.
There are github repositories for the varios components, so the entire development appears to be very transparent:
Since this is a joint effort by two developers of lighting simulation software (Dial and Relux) rather than the next closed and proprietary format, it might be worth to think how Radiance could provide an interface, too.
Best, Lars.