Is this a lighting bug? How to solve it? Many versions have this problem.

  • Rick Marx

    Approved the thread.

    yyx718186659 , thanks a lot for your post.


    In this case, you may instead also try adding some light strips through the use of emissive surfaces - the behaviour at hand you're seeing can be normal, but I'd also be curious if this changes when you increase the thickness of the objects on which the current light is falling on? Just to make sure since I've had a similar case before and this should be something that is already resolved - so, please make sure to also use our latest release if you haven't already!

    Hello Woon interieurontwerp ,
    The rectangular light emits light from a single point in the middle of the surface. If you'd like to share any requests to change this behavior, please feel free to do so in our online portal right here:
    https://portal.productboard.co…bs/17-under-consideration
    For your usecase, have you considered just using a line light instead?

    As users we take our cues from the information provided to us by you guys. In this case by calling it a rectangular light, you are telling users the light emits from the areas defined evenly. Why call it that if you only emit from a point?


    Thanks!

    Quote from renderwiz

    As users we take our cues from the information provided to us by you guys. In this case by calling it a rectangular light, you are telling users the light emits from the areas defined evenly. Why call it that if you only emit from a point?


    Thanks!

    Pardon the confusion but, basically every real-time rendering engine makes use of lights which aren't just spotlights, yet many can act similar to one which is due to technical limitations which we cannot circumvent either. That still doesn't mean we do not want to label our lights as such even if they are affected by the typical distance limitations.


    Otherwise no real-time rendering software would be able to offer lights that are non-spotlights as again, they all have their limits. Only raytraced lighting (a technique that makes light in real-time rendering engines behave like it does in real life by simulating actual light rays, using an algorithm to trace the path that a beam of light would take in the physical world.), which works differently compared to the traditional 3D rendering methods used, and also requires a lot more performance and a corresponding capable card would be able to work around this but it's not something we've implemented yet. (Not for lighting but raytraced sunshadows/reflections are already implemented)


    Hope that clears things up a bit further - If any other specific questions come up let me know.

    Thanks for that explanation. My question was originally to suggest that Kajs explaination was too simple and yours is certainly more complex :-)


    Still haven’t heard an explanation on how they are different than regular spotlights. My goal was to encourage a more useful description so other users understand the uses and limitations of rectangle lights.


    I’ll take a stab at it for you and you can correct me if I am wrong.


    Rectangle lights have a rectanglular falloff mask or cone rather than a circular one. The light still comes from one point but the way it hits a surface looks like a blurred rectangle rather than a circle. It is especially effective when the light is not very close to the surface.


    How’s that?

    There is an unreal Engine document here that talks about the type of parameter that is adjusted to make the type of light enscape has labelled as a strip light.

    Obviously enscape is not unreal engine based, but they will share a lot of similar techniques.


    https://docs.unrealengine.com/…entExamples/Lighting/5_3/