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4.20 lighting changes, is there a way to revert it back?

SchaakaSchaaka Posts: 147
in New Users

Im probably late to the party on this one but I recently updated Daz and I noticed that the lighting I was using no longer works.

It was weird, the more opacity something had it would give less light.

Googled around and found out its a bug or something to do with the 4.20 update. Small relief it wasnt just me.

Found one guys solution which was to blast up the lum to near max, which does work but is kinda unwieldy.

Is there a simple way to revert the light changes back? I have a lot of scenes set up and I dont want to have to fiddle with all their settings again just to make it look like it did before.

Or maybe I should use some other method of lighting?

Suggestions?

Thanks!

Comments

  • murgatroyd314murgatroyd314 Posts: 1,515

    Technically, it wasn't a bug in the update, but a bug fix. Unfortunately, a lot of people including you had been taking advantage of the bug to get a desired effect without realizing it was a bug.

  • SchaakaSchaaka Posts: 147

    murgatroyd314 said:

    Technically, it wasn't a bug in the update, but a bug fix. Unfortunately, a lot of people including you had been taking advantage of the bug to get a desired effect without realizing it was a bug.

    Do you know any way to emulate the same effect?

    I dont get how this is a bug fix, its not like Daz is a video game where players are circumventing a challenge. Surly Daz has something similar then?

  • GordigGordig Posts: 10,047

    Schaaka said:

    murgatroyd314 said:

    Technically, it wasn't a bug in the update, but a bug fix. Unfortunately, a lot of people including you had been taking advantage of the bug to get a desired effect without realizing it was a bug.

    Do you know any way to emulate the same effect?

    I dont get how this is a bug fix, its not like Daz is a video game where players are circumventing a challenge. Surly Daz has something similar then?

    It was a bug because it isn't physically accurate, which is why Nvidia changed the behavior in Iray. Daz had nothing to do with the change.

  • jjoynerjjoyner Posts: 616
    edited July 2022

    Schaaka said:

    Im probably late to the party on this one but I recently updated Daz and I noticed that the lighting I was using no longer works.

    It was weird, the more opacity something had it would give less light.

    Googled around and found out its a bug or something to do with the 4.20 update. Small relief it wasnt just me.

    Found one guys solution which was to blast up the lum to near max, which does work but is kinda unwieldy.

    Is there a simple way to revert the light changes back? I have a lot of scenes set up and I dont want to have to fiddle with all their settings again just to make it look like it did before.

    Or maybe I should use some other method of lighting?

    Suggestions?

    Thanks!

     There have been several threads in the forums since this issue regarding ghost Lights (mesh lights) arose earlier this Spring.  One such thread is Problems lighting with emissives recently (https://www.daz3d.com/forums/discussion/575741/problems-lighting-with-emissives-recently#latest) in which I posted:

    • The Nvidia change that affected how ghost lights work caught almost everyone by surprise a few months ago.  I was using version 4.15 at that time so it did not affect me.  I'm a retired hobbyist.  However, I took the plunge a month or so after the issue arose and upgraded to version 4.20.  I played around with the "new" ghosting lighting methodology and used a ghost light in a scene last week with no problem. Basically, by whatever factor you divide the opacity by, you have to multiply to luminence by the same factor.  For example, if the ghost light opacity is initially 1 and its luminence value is 1500, and you divide the opacity by a factor of 1,000,000 (making the opacity 0.000001), then you have to multiply the luminence by the same factor of 1,000,000 (making the luminence 1500000000.

    Some vendors are updating their ghost light product to incorporate this rendering change.  Of course, if the scenes that you need to work with use your own ghost lights or ghost lights from vevndors who aren't updating their product, then this won't help you.  To my limited knowledge, the only way to revert this back is to use a version of Daz Studio prior to 4.20. 

    Post edited by jjoyner on
  • TynkereTynkere Posts: 834

    I'd had the same problem with emissive planes where cutout opacity is .00010.  In V4.20 cutout acts as a sort of redundent efficiacy setting.  Another dimmer switch so to speak. 

    Anyway, was holping someone had a ratio.  Will give it a try.  Thanks.

  • jjoynerjjoyner Posts: 616

    Tynkere said:

    I'd had the same problem with emissive planes where cutout opacity is .00010.  In V4.20 cutout acts as a sort of redundent efficiacy setting.  Another dimmer switch so to speak. 

    Anyway, was holping someone had a ratio.  Will give it a try.  Thanks.

    This is a case of inverse variation between two quantities.  As one quantity increases (or decreases), the other quantity decreases (or increases).  They change in opposite directions.

    • Quantity A = K/Quantity B  where K is the constant of proportionality for the situation. 


    Another way to write an inverse variation is as a product:

    • (Quantity A)(Quantity B) = K.

    So,

    • Opacity = K/Luminance  OR  Luminance = K/Opacity  OR  (Opacity)( Luminance) = K

     

    The default opacity of an object is 1 and, unless one changes its parameters, has a range from 0 to 1.  The default luminance of an object is 1500 cd/m^2 until one changes it.  So one’s starting position with a ghost light is

        (Opacity)( Luminance) = K

        (1)(1500) = K

        1500 = K.

    Thus, to make the change into a ghost light, if you set Opacity to 0.0001 (one ten-thousandth of its initial value), then

        Luminance = K/Opacity

        Luminance = 1500/(0.0001)

        Luminance = 15,000,000 (ten thousand times the original value).

     

  • TynkereTynkere Posts: 834

    jjoyner said:

    This is a case of inverse variation between two quantities.  As one quantity increases (or decreases), the other quantity decreases (or increases).  They change in opposite directions.

    • Quantity A = K/Quantity B  where K is the constant of proportionality for the situation. 


    Another way to write an inverse variation is as a product:

    • (Quantity A)(Quantity B) = K.

      <snip>
        (Opacity)( Luminance) = K

        (1)(1500) = K

        1500 = K.

        Luminance = K/Opacity

        Luminance = 1500/(0.0001)

        Luminance = 15,000,000 (ten thousand times the original value).

     

    That looks insane but I'll try it! 

    Thanks for reply. :)

  • jjoynerjjoyner Posts: 616
    edited July 2022

    That looks insane but I'll try it! 

    Thanks for reply. :)

    It's easier than it looks.  If you divide the opacity value (decrease) by X, then muliply the luminance value (increase) by X.

    Joe

    (Retired MathGuy)

    Post edited by jjoyner on
  • TynkereTynkere Posts: 834

    No problem.  Since I retired, need to shake the rust off math skills.  15 million had me thinking of emergency landing lights at the airport or something.  Crazy but 3D is still a fun hobby.

  • RaukoRauko Posts: 32

    I made a video on this .. 

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