Smooth Indirect/Concealed Lighting

[Sampdoria]

Dear Team

Ive been doing ID Renders in Nxt and Ar3 and I keep forgetting to ask how everyone gets a smooth bulkhead light effect? See sample from random internet image.

I usually model a region and tag it as a spot or omni light but effects vary, I still dont get

a smooth continuous strip of LED Light.

Peter and Others? :)

Cheers