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Thread: 3ds Max 2015 iRay LPE - how to use?

  1. #1
    Join Date
    Dec 2014

    Default 3ds Max 2015 iRay LPE - how to use?

    Hello everyone!

    I was really excited to get to know about iRay LPE (Light Paths Expressions) functionality in 3ds Max Design 2015, however I have difficulties with using it. I've searched the Web but found no sufficient explanation on how to use iRay LPE. I hope you will be able to help me with understanding it better.

    My situation is as follows: I have a scene and I want every light (or group of lights) rendered to an individual frame for later composing (just like in the promo video that was released just before Max 2015). How can I achieve such result?

    I go to Render Setup>Render Elements>Render Elements and use Add> Light:Point. In Paramterers it has a default Light Path Expression "Lp.*E". If I render as it is, I get all point lights rendered to a single frame. What I need is to have each light or group of lights separated, so that in composing I can adjust them independently (like here: or here As far as I understand, I need to label the lights (or groups of lights) and use those labels in the parameters string, however dispite all my efforts I couldn't make it work. Please support me with a sample command for separating lights into individual frames.

    Perhaps you will be able to answer another question of mine: how many lights (or groups of lights) can I render at the same time (that is in one pass) in 3ds Max Design 2015?

    LPE is a great feature, but it's a bit confusing and diffcult to use at the moment (especially for someone not so tech-math-IT-literate). I believe some simple guidelines with examples will be of a help to many users.

    Many thanks in advance!

  2. #2
    Join Date
    May 2011
    San Francisco, CA



    Go to There you will find a number of posts with LPE examples and some example scenes.
    Lots of LPEs to look at. Keep in mind that some features of LPE e.g. Handles have not been fully implemented yet in
    MAX 2015


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