Hi
I have a mesh light, the growing geo, and the problem is that the Arnold mesh light intensity is for the object, so it emits the same amount of light whatever is the size of the mesh, so I calculated surface area attribute passed it to the detail (sum it for the whole mesh) and want to use it now in light intensity (or light Exposure) but I'm just can't get it to work…

pretty straightforward to do using the ‘detail’ expression in the intensity parameter of your light. if your attribute promote node was in ‘geo1’ and named ‘attribpromote1’ that would look like

Thanks Brian, on my way home it goes to my mind. First the opimputpath or this. I was probably just confused, because I cached the geo and the attribute is present there on the light. But obviously a bit overthinking. :-) thanks.