Dome Light(s)

[mitchino]

I think I may have asked something similar before...

Will Octane ever get Dome Lights? Or is it possible to have multiple hdri environment and use light linking to restrict each hdri to different objects?

[frankmci]

HDRI Dome lights are easy enough to make with simple geometry, and then you can use Light ID/Light Pass Mask with them to control illumination on a per object/set basis.

As I understand it, Environment Lights are automatically mapped to the "e" Light ID, of which there is only one. By making your own dome lights, you can assign them to any of the eight other available ID channels.

[mitchino]

Thanks for info. I'm assuming you mean make a sphere object with an hdri mapped spherically to the inner surface? Do you know how big I should make the sphere relative to other objects in the scene, so it matches the look of using an hdri environment?

[SSmolak]

Such spheres or other objects for simulate dome light or reflection backdrop plates are not the best way to use in Octane because they block camera viewport manipulation, surface & dof pickers.

[frankmci]

Such spheres or other objects for simulate dome light or reflection backdrop plates are not the best way to use in Octane because they block camera viewport manipulation, surface & dof pickers.

Yes, they are not ideal, but are a decent workaround if you need it. On the occasions where I do need them, I turn off their visibility in the UI to get them out of the way, but still render.

[frankmci]

Thanks for info. I'm assuming you mean make a sphere object with an hdri mapped spherically to the inner surface? Do you know how big I should make the sphere relative to other objects in the scene, so it matches the look of using an hdri environment?

Yup, or a hemisphere, depending on your needs. Just make sure the surface normals are flipped so it renders on the inside and put the HDRI in the Emission channel. I don't have any specific numbers, as far as size goes, but make it big enough that no geometry is too close to the emitting surface to avoid hot spots. Also, the more camera movement distance you have, the farther away the dome needs to be to avoid obvious motion parallax, blowing the illusion. One option to avoid this without scaling up, scene allowing, is to drive the dome's X Z position with the render camera's so that it remains at a constant distance.

If you plug a "Side" node into the opacity of the dome material, you can set it so that only the inside of the dome is visible in the Live Viewer. This way you don't have to worry about the dome itself blocking your view.

[SSmolak]

I turn off their visibility in the UI to get them out of the way, but still render.

but still visible for camera manipulation in Octane Live Viewer and for pickers.

[mitchino]

Thanks, some great info.

I don't want to see the hdri, I just want to use it for lighting. Ideally I want to be able to use an hdri the same way I use other lights, to be able to link them to certain objects, and to be able to use 'visible on diffuse' and 'visible on specular'.

That's why I asked about dome lights