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Thread: Luminous power and artificial lights with VRaySun and Exposure

  1. #1
    Junior Member kristofferhelander's Avatar
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    Kristoffer Helander
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    Question Luminous power and artificial lights with VRaySun and Exposure

    Hi everybody,

    I have an interior scene with VRaySun and VRaySky and some Skyportals, I use a standard camera but with VRay Exposure Control in the Environment Dialogue and I render either with Gamma in the Color Mapping rollout set to 1.0 or 2.2 with the Don't affect colors (adaption only) option ticked.

    When I add VRayLights to the scene to represent light bulbs they hardly add anything to the overall illumination. I set the Intensity Unit to Luminous power (lm) and test values between 1000 to 3000 lm, from what I gathered from a lamp/light reseller website that's round about what a 100W light bulb has, around 1000lm. But as I said, they hardly brighten the scene at all. The Colour Temperatur I set to round about 2700K, what gives it a yellowish tint. Is this due to that the exposure is set to work for the VRaySun?

    If you want to brighten a particular part of the image, how would you do that, since the VRayLigts doesn't do much unless I set the lumen to like 50000 or so, but then it looks very strange for it is much brighter closer to the source and falls of vary rapidly; which I guess is due to the Inverse square law. Brighten it up in post? Or use "light cards" (not sure what it's it called) to bounce in extra lights, like photographers do?

    Thanks, cheer!
    //Kristoffer
    Last edited by kristofferhelander; April 17th, 2012 at 03:15 PM. Reason: spellchecking

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    Corey Beaulieu
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    Default Re: Luminous power and artificial lights with VRaySun and Exposure

    2 things come to mind with this:

    1) The white Balance of the camera can very quickly over power the color value of light. It is, in fact, what it's there for. Try setting this to neutral.
    2) Secondly. If you turn on a light inside on a well lit sunny afternoon, that light won't have much, if anything, to do with the over all color of a photograph. 3D is no different. You need to set your sun for time of day and then your lights will have more weight in the image.

    *If you are creating a mood render where lighting is very important, you will likely want to ditch your skylight portal, which I suggest anyway as a beginning and go with the artificial lights all around on the interior. Checking "Invisible" will get rid of the floating hotspots and the Inverse square will disperse the light accordingly. Do the same with some Vray Plane lights and angle them where you need more light (light cards) and color them to add more mood. Think of them as implying that there is another room whose light is spilling over into your image or a blue-ish one can imply a window in the daytime. Etc…

    Hope this gives you a few ideas.
    Last edited by CoreyMBeaulieu; April 19th, 2012 at 07:09 AM.

  3. #3
    Junior Member kristofferhelander's Avatar
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    Kristoffer Helander
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    Default Re: Luminous power and artificial lights with VRaySun and Exposure

    Cheers mate! That's what I wanted to hear!

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