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iray renders are black when using a skydome

R GolbraithR Golbraith Posts: 45
in Daz Studio Discussion

Hey, Guys.

Ever since I installed Daz 4.9 when I put a skydome in the scene and try to render everything comes out black. It happens even when I use the preset lighting for that skydome. I have tried to up the gamma, and the iso. it helps just a small bit. I can see the outline of the character but nothing else. And Reality render or LUX has the same issue. When I use 3Delight I don't have this problem but that render engine isn't all that good. Any help on this would be appreciated.

Comments

  • KhoryKhory Posts: 3,854

    A skydome is a mesh that is blocking any HDRI environment lighting from getting to your scene. You can apply the uberiray shader to the dome and then go down to emissive and put the texture for the dome in the color channel and change it to white and use it as a lighting source (you will need to play with luminosity for strength) or you can use a different kind of lighting inside the dome as lighting.

  • R GolbraithR Golbraith Posts: 45

    Interesting. I'll try it out. Thank you.

  • shaylia_evashaylia_eva Posts: 18

    Best advice I ever heard about this, thank you.  I was wondering the same thing.

  • ToborTobor Posts: 2,300

    While making a skydome self-luminate can be an approach to both creating light and a background, there are some issues you need to be aware of.

    First, unless you use a more technically complex approach, light from any geometry is diffuse, meaning it goes out in all directions evenly. This can create a very flat all-around lighting that can steal the realism from your scene, and causes it to lose impact. If you look at the really good renders posted here, the vast majority of them use directed light that also provides shadow.

    Second, depending on the gemoetry of the dome, it can add considerable time to the render. The more facets (divisions) the dome has, the more individual sources of light that Iray must calculate. It can add a lot of time.

    Third, No light outside of the dome (Iray environment, distant, even far-away placed spots) will get through the skydome, so you lose the ability to use those lights for your scene.

    There are some Iray-specific skydomes in the marketplace here that get around one or all of the above problems, and you can create your own. One thing that can work is a partial skydome. You can rotate the skydome so that it's always visible in the camera, but it still lets in light from the front and/or top. Several folks in the forum have developed techniques to allow light outside a skydome to enter, using different Iray shader techniques, making certain parts of the skydome geometry invisible, or using the Iray sectioning plane.

    In other words, there are many ways to do this. My best advice is to investigate as many as you can, and try them out. Each technique provides different advantages and looks. Pick the one that works best for YOUR art.

  • Bryan ValenciaBryan Valencia Posts: 55

    so... what is the "Iray" way of doing skies if the dome is not compatible?  There should be some way to set a sky dome to "no shadow" somewhere, shouldn't there?

  • gibbiejoegibbiejoe Posts: 50

    Thank you, can somebody name some Iray-specific skydomes mentioned here above?

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