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Above we use the most common ways to collect light paths, you either want all, direct, or indirect. This handles most scenarios you come across. But there may be reason to do something with a specific bounce or set of bounces. This can be anything from non-physical scaling of the light (brighter or darker) or isolating a specific bounce where noise is introduced and subtracting it from the final result. This last example is best when you can isolate the object(s) causing the noise. This will be covered under LPE Groups. Below is an example of rendering only the first (direct light), seconsecond, and third light bounce. These LPE are all very similar to the Beauty LPE but we exchange the * for all bounces with a specific bounce contained in a curly bracket {} For example, {1} collects the first bounce or the direct light frm the ceiling rect light to the object and then immediately to the camera. The second bounce is {2} which says the light must interact with something one more time before being stored, this is the first indirect bounce after light meets a surface. This goes on until the path length is terminated by the parameters in the Render Settings, Max Specular/Diffuse depth and/or Max Path Length for the integrator and possibly russian roulette Russian Roulette early termination (all the energy was already absorbed leaving you with no more information to store).

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lpe:C<[RT][DS]>{1}[LO<L.>O]
lpe:C<[RT][DS]>{2}[LO<L.>O]
lpe:C<[RT][DS]>{3}[LO<L.>O]

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