[jfrancis]

Can I hide physical sky from camera and still receive its lighting effects on objects?

Would it speed rendering?

[Bubbaloo]

You can use a combination of phys sky and IBL to achieve this. You can set your phys sky settings, turn on IBL and disable illum, reflect, refract, and put a background image of your choice (enabled). Make sure "Use for disabled" is set to phys sky.

[JTB]

But I think the question was if this speeds up rendering....

[Bubbaloo]

But I think the question was if this speeds up rendering....

I saw two questions. I answered one of them.

[jfrancis]

Thank you both.

I tried network rendering on this scene for the first time, and I requested it render an alpha channel for the first time, and I saw the object isilated on black in the RGB image, and the alpha isolated on black in the alpha image.

It was late and I left it at that. Will explore more today, but it looked like I somehow inadvertently got the effect I was looking for.

I didn't compare render times.

[JDHill]

The render time should not change. Think about rendering a chrome ball -- what can be reflected, which has not first been calculated?

[jfrancis]

I just thought the 80% of the image which is black might not, itself, require a calculation to fill in thew sky.

Or I might find a lower SL acceptable on the main object if I don't have to fill in every pixel on the screen.