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Skydome luxus

Ali BozisAli Bozis Posts: 39
edited December 1969 in Daz Studio Discussion

How do i use a skydome when rendering with lux?

My picture is all black, looks fine when i turn off skydome, so i guess i need to shut of the shadows somewhere, but where??

Comments

  • SandmanGFXSandmanGFX Posts: 75
    edited December 1969

    I'm a Reality user and I haven't got Luxus, but it would be a huge surprise to me if switching off shadows is actually possible here, since Luxrender always renders shadows. In Reality you'd have to convert the skydome into a Reality light material. Maybe try dialling up the skydome's ambient strength and maybe change its ambient colour to something a bit brighter. I only read that Luxus automatically converts the DS materials automatically to lux materials. How well it does it, I don't know. Let me know if this works for you.

  • SimonJMSimonJM Posts: 5,980
    edited December 1969

    Whilst Daz Studio knows what a skydome is and will allow light from a Distant Light to pass through it, LuxRender just sees it as a 'whopping big' (hemi-)sphere of geometry that will tend to stop light from outside it (the Sun, for example) passing. A couple of things you can do (neither of which will help render speed!!!!): make the skydome a matte translucent material, or convert it to a light emitter (which will give a pseudo-HDRI effect).
    A better way would be to find a good, proper HDRI and incorporate that into the render.

  • SandmanGFXSandmanGFX Posts: 75
    edited December 1969

    Oh yes! There are some amazing free sIBL's on the HDRLabs website. Apparently they're the fastest option regarding HDRI's and render time. They're really worth having a look at, even if you don't end up using them in the end. I'm absolutely fascinated with them.

    Anyway... if "light emitter" is an option with Luxus, this would be what you're wanting. I'm guessing it'll give you the more accurate render of the two options SimonJM mentioned above. It should be equivalent to working with the ambient channel of the skydome's material. It's just the question of how Luxus translates the materials to LuxRender.

  • Herald of FireHerald of Fire Posts: 3,504
    edited December 1969

    A.B.A said:
    How do i use a skydome when rendering with lux?

    My picture is all black, looks fine when i turn off skydome, so i guess i need to shut of the shadows somewhere, but where??


    Skydomes are not recommended for use in Luxrender. The issues are twofold. Firstly, if you use 'sun' or other directional lights the light cannot penetrate the exterior of the dome. Secondly, if you use smaller mesh lights, then the light has to travel all the way to the skydome and back again, which vastly increases render times since the light keeps bouncing around.

    As mentioned, IBLs are recommended. They can not only provide a background, but allow sunlight to pass through and have no geometry of their own.

    If you're interested, I have some Luxus presets (link in signature) which might be useful. They'll give you a background much like a skydome but without the geometry. The sphere which will appear when loaded into the scene does not render in Lux, so can be used as a guide for orienting the light..

  • Ali BozisAli Bozis Posts: 39
    edited December 1969

    Thanks a lot for the answers. And great IBL's :)

    I have another question, how do i catch shadows under my car??? If I want to use the IBL as background??

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  • Herald of FireHerald of Fire Posts: 3,504
    edited December 1969

    A.B.A said:
    Thanks a lot for the answers. And great IBL's :)

    I have another question, how do i catch shadows under my car??? If I want to use the IBL as background??


    Shadow catchers don't work in Luxrender because it requires actual geometry. It's not recommended to use the IBL's as full backgrounds for this reason, but more as an addition to existing terrain to add skies or other useful articles.

    When I created the first IBL preset, I used a bridge, for example, suspended in a way to make the resulting background believable. You need to use a little wit and cunning when positioning your props so that you can get a good effect.

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  • SandmanGFXSandmanGFX Posts: 75
    edited December 1969

    I'd photoshop two renders together. One using the IBL, the other one using the shadow catcher. Experiment with the blending options. Usually I'd cut the model (car in your case) out of the shadow catcher's image as much as necessary, but it might not be necessary. You could get some nice results, purely by changing the blend options.
    The shadow catcher tutorial should still be out there I'm guessing.

  • Herald of FireHerald of Fire Posts: 3,504
    edited December 1969

    SandmanGFX said:
    I'd photoshop two renders together. One using the IBL, the other one using the shadow catcher. Experiment with the blending options. Usually I'd cut the model (car in your case) out of the shadow catcher's image as much as necessary, but it might not be necessary. You could get some nice results, purely by changing the blend options.
    The shadow catcher tutorial should still be out there I'm guessing.

    If you have Photoshop it's quite easy to cut out the car image using the selection tools. Make two 3DL renders. One with the shadows on, and one without, and using the same camera angle as the Luxus render. Using Photoshop, CTRL-select the layer with only the car on it and save the selection, then load the selection onto the shadowcatcher render. Hit delete and you'll remove the car from the image and be left with only the shadows.

    You can then overlay the shadows on your Luxus render.

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