VRayBitmap

[jackieteh]

Hi, may I know what is the difference between this two parameter?

It seem like both of the setting also affects rendering and material editor

[Joelaff]

I think the idea is that Render Multiplier should not affect the viewport, only anything that renders (which would include the material editor). Whereas Overall Multiplier would affect both.

[jackieteh]

thank you for your reply, but if I set overall multiplier to 0, render multiplier to 1, no light in the scene, when set opposite, no light in the scene too

[Joelaff]

That sounds right...

Light output at render time would be Overall Multiplier * Render Multiplier * Image
Light output in the viewport (if you get light in the viewport, but the exposure of the texture) should be Overall Multiplier * Image

So if you put a zero in either setting the render output would be zero. I never get viewport preview to work well anyway (and never really try to see lighting in the viewport).

[jackieteh]

so what should I do if I want to see HDRI image outside the window, and still want to get it to light up interior?

[Joelaff]

Oh, that's a different sort of question. The trick with inside and outside is to either use tone mapping to bring down the outside, or try to better balance the interior and exterior levels more by brightening the interior lights, or darkening the HDRI outside. In real world photography you would either add more light inside, or you would put ND film on the windows to darken the outside. Or you would wait until a darker time of day to take the picture.

Start with some tone mapping.

[jackieteh]

Noted with thanks