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Question about lighting

TrishTrish Posts: 2,625
edited December 1969 in New Users

I am not understanding ....What is shadow bias?? Thanks in advance...Trish

Comments

  • XoechZXoechZ Posts: 1,102
    edited December 1969

    Shadow bias is some kind of offset for shadows. If you increase the ammount, then the shadow moves away from the figure. It sometimes helps when you have problems with deep shadow maps. But with raytraced shadows you never need it, except you need that effect for some reason.

  • TrishTrish Posts: 2,625
    edited December 1969

    Ok Thank you ....I just was not seeing what it did appreciate your help.....Trish

  • SzarkSzark Posts: 10,634
    edited February 2014

    To be more precise Shadow Bias might need adjusting with Ray Traced Shadows if an object in tiny then a value of 0.10 may be needed. Just something to consider. :) But generally 1.00 should do most images.

    Post edited by Szark on
  • Richard HaseltineRichard Haseltine Posts: 101,113
    edited December 1969

    The Shadow Bias is, as XoechZ says, an offset and it's measured in CM. It's used to prevent self-shadowing, which usually shows as dark bands across surfaces, but it can cause problems such as nostril glow (because the space is smaller than the offset, so no shadows get applied) or blotchiness under close-fitting translucent garments such as tights, where some areas get shadowed and some don't.

  • Miss BMiss B Posts: 3,071
    edited December 1969

    Thanks for that Richard. I rarely look at that parameter, but at least now, after all these years, I know what it's for. :coolsmile:

  • SpottedKittySpottedKitty Posts: 7,232
    edited December 1969

    Richard Haseltine said:
    or blotchiness under close-fitting translucent garments such as tights, where some areas get shadowed and some don't.

    Not so much blotchiness, it's more like the shadow abruptly stops as the clothes mesh gets closer to the figure mesh. And as far as I can see, it's all clothes, translucent/transparent or not. I used to see this all the time until I finally learned how to adjust the Shadow Bias setting properly.

    Note that sometimes, turning the setting down enough to give good shadows will affect the render time. It's yet another "faster or better, not both" decision you'll have to settle for yourself.

  • TrishTrish Posts: 2,625
    edited December 1969

    It sounds like using it is a lot of trouble....or probably would be for me anyway...I think I will just experiment in my spare time with it and see how it goes.....Thanks All....Trish

  • XoechZXoechZ Posts: 1,102
    edited February 2014

    No, it is quite the opposite. You have to use it only when you have troubles (with wrong looking shadows)! :-)

    Post edited by XoechZ on
  • SzarkSzark Posts: 10,634
    edited December 1969

    XoechZ said:
    No, it is quite the opposite. You have to use it only when you have troubles (with wrong looking shadows)! :-)
    exactly....don't make it more complicated than it is.....many things are easier than people think....well That is what I found when I started learning.
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