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Thread: Geometry Casting Shadows

  1. #1
    Join Date
    Apr 2018
    Posts
    3

    Default Geometry Casting Shadows

    Is there a way to make geometry not cast shadows in iray? For instance, the geometry would be visible in renderings and receive light, but it allows light to pass through without casting a shadow so that the geometry beyond is also illuminated by the light source.

    Previously, when I was using a different rendering engine, I was able to un-check the "Cast Shadows" option in the advanced lighting tab of the object properties to achieve this effect. This is really useful for modeling decorative fixtures and using manufacturer's .ies files for the actual light source.

    Is there a way to accomplish this in iray? Otherwise, it would be awesome if a feature like this could be added at some point.

  2. #2
    Join Date
    Dec 2017
    Posts
    5

    Default

    I also have noticed this limitation when using ies files for certain types of light fixtures (direct/indirect fixtures, decorative pendants, and outdoor bollards). It would be great to have the option proposed by Skip or at least the Shadows "Exclude" option for photometric lights available.

  3. #3
    Join Date
    Nov 2017
    Posts
    233

    Default

    Hi,

    Unfortunately this is not possible with the Iray+ render mode. Iray is a physically-based path tracer and the behaviour you see is a fundamental aspect of the renderer and cannot be changed.

    Having said that, the Iray+ Interactive render mode, which uses various approximations and is not physically accurate in the same way, is technically able to do this, but we don't currently expose controls to allow this in the plugin.

    Would this be useful if it was only available with the Iray+ Interactive render mode? Or would you require this in the Iray+ render mode as well?

    Thanks,
    Michael
    QA Engineer, Lightworks

  4. #4
    Join Date
    Dec 2017
    Posts
    5

    Default

    I think that it could be helpful in Iray+ Interactive for some applications. This would be the only physically accurate way to simulate some types of luminaires using an ies file, aside from rendering multiple images and post-processing in photoshop. The only problem I see is that lighting analysis functions are not supported in interactive which limits the usefulness for my purposes. Is lighting analysis something that could also be enabled for interactive mode, or would it not be accurate based on the approximations?

  5. #5
    Join Date
    Nov 2017
    Posts
    233

    Default

    It certainly wouldn't be accurate for anything other than direct lighting, and the irradiance canvas is not supported for this render mode in Iray at all, so isn't something we could enable.

    The problem with luminaires and IES files has been raised before, so it may make sense to enable this option for the Iray+ Interactive renderer (even with the lack of lighting analysis). I can add a feature request for this.

    Thanks,
    Michael
    QA Engineer, Lightworks

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