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How to Avoid...Backlight Burn?

MelissaGTMelissaGT Posts: 2,611
in The Commons

I've been working on an early WIP and have run into a sort of conundrum...

See the areas highlighted...I believe they are happening because of the extreme backlighting...and I can't figure out how to get rid of them. This is Daz 4.20 and I do have spectral rendering turned on...though that does not make a difference. The skin settings themselves do not have an over-abundance of transmission, as you can see with his ear that is not overblown (transmitted distance is set to .05 on him, so it's not high at all). I tried this same scene in Daz 4.15 because I know there were some changes as to how the spectral render behave between the two versions...but the issue was there too. Any thoughts on how to avoid this? Turning spectral rendering doesn't help either. I had to make some adjustments to his hair cap because it was worse, where the cap intersected with his head...but I can't get that one last bit to go away. I can even deal with that spot, as it is tiny and I can fix it in post...what really concerns me is the spot where his arm bends. I believe that's where his mesh intersects itself slightly due to the arm bend. 

Any help is appreciated!

Comments

  • MelissaGTMelissaGT Posts: 2,611
    edited March 2022

    Well, that was easy! Happened to turn off the full-body geoshell (horizon vellus hair) and it went away! Now I know I can do two passes, one with and one without, in order to not have that show up in the final piece. 

    Post edited by MelissaGT on
  • WendyLuvsCatzWendyLuvsCatz Posts: 38,529

    OMG I need new reading glasses, I misread this thread as How to Avoid..Backlight Bum blush

  • MelissaGTMelissaGT Posts: 2,611

    WendyLuvsCatz said:

    OMG I need new reading glasses, I misread this thread as How to Avoid..Backlight Bum blush

    You actually made me go back and check the title to make sure I didn't say Backlight Bum! 

  • AndrewJJPAndrewJJP Posts: 720
    edited March 2022

    MelissaGT said:

    Well, that was easy! Happened to turn off the full-body geoshell (horizon vellus hair) and it went away! Now I know I can do two passes, one with and one without, in order to not have that show up in the final piece. 

    I very much doubt I am telling you something you don't know, but you can turn off the shell and use the spot render tool to just render the bad bit rather than do another pass of the whole thing. I have never had any issues doing that anyway.

    Lovely pic BTW.

    Post edited by AndrewJJP on
  • McGyverMcGyver Posts: 7,066
    edited March 2022

    WendyLuvsCatz said:

    OMG I need new reading glasses, I misread this thread as How to Avoid..Backlight Bum blush

    Since you read it as "How to Avoid Backlight Bum", and were obviously curious, I'll share my method... I got an old backpack shoulder harnesses from a Army-Navy Surplus store and mounted two gooseneck LED high intensity spot lights (each around 3k lumens) on outriggers, pointing downward... usually this is bright enough to compensate for any regular backlighting that might create undesirable silhouetting, especially when standing in front of a partially bright sunset.

    Its a bit hard to run like that, but it makes its point and even though it goes through batteries fairly quickly, it's cheap to do.

    I actually thought the title was "How to Avoid Blacklight Bum" and was getting ready to suggest various creams that reduce bum fluorescence under black light conditions... Rump-O-Tone is one product... it's very effective when streaking through a rave or discotheque and allows for an even bodily tone, especially if one has a particular shiny rear or there are lots of strobe lights.

    I personally feel the glowier a rump, the more interesting... especially when using dayglow paints... but that's just me.

    Post edited by McGyver on
  • MelissaGTMelissaGT Posts: 2,611

    AndrewJJP said:

    MelissaGT said:

    Well, that was easy! Happened to turn off the full-body geoshell (horizon vellus hair) and it went away! Now I know I can do two passes, one with and one without, in order to not have that show up in the final piece. 

    I very much doubt I am telling you something you don't know, but you can turn off the shell and use the spot render tool to just render the bad bit rather than do another pass of the whole thing. I have never had any issues doing that anyway.

    Lovely pic BTW.

    Thank you! And in this case, with such heavy bloom, you can't use the spot render. As bloom is based on what is in the rendered window, a spot render will not render with the same amount of bloom as the whole scene...so they won't match up when you try to blend them together. It's not a worry for me...the 3090 should make quick work of it. 

  • AndrewJJPAndrewJJP Posts: 720

    MelissaGT said:

    AndrewJJP said:

    MelissaGT said:

    Well, that was easy! Happened to turn off the full-body geoshell (horizon vellus hair) and it went away! Now I know I can do two passes, one with and one without, in order to not have that show up in the final piece. 

    I very much doubt I am telling you something you don't know, but you can turn off the shell and use the spot render tool to just render the bad bit rather than do another pass of the whole thing. I have never had any issues doing that anyway.

    Lovely pic BTW.

    Thank you! And in this case, with such heavy bloom, you can't use the spot render. As bloom is based on what is in the rendered window, a spot render will not render with the same amount of bloom as the whole scene...so they won't match up when you try to blend them together. It's not a worry for me...the 3090 should make quick work of it. 

    I have one of those too. Good aren't they!. Unfortunately. I make my pictures enormous and they still take a few hours...

    I can see how that would be an issue there, with such an extreme backlight. Is it purely an HDRI? (I watched the course you were involved with - I was listening!)

  • MelissaGTMelissaGT Posts: 2,611

    AndrewJJP said:

    MelissaGT said:

    AndrewJJP said:

    MelissaGT said:

    Well, that was easy! Happened to turn off the full-body geoshell (horizon vellus hair) and it went away! Now I know I can do two passes, one with and one without, in order to not have that show up in the final piece. 

    I very much doubt I am telling you something you don't know, but you can turn off the shell and use the spot render tool to just render the bad bit rather than do another pass of the whole thing. I have never had any issues doing that anyway.

    Lovely pic BTW.

    Thank you! And in this case, with such heavy bloom, you can't use the spot render. As bloom is based on what is in the rendered window, a spot render will not render with the same amount of bloom as the whole scene...so they won't match up when you try to blend them together. It's not a worry for me...the 3090 should make quick work of it. 

    I have one of those too. Good aren't they!. Unfortunately. I make my pictures enormous and they still take a few hours...

    I can see how that would be an issue there, with such an extreme backlight. Is it purely an HDRI? (I watched the course you were involved with - I was listening!)

    Yeah, that's all HDRI lighting. I'm still working on putting the scene together so I haven't settled on it yet, but I do love the halo effect it produces for the mood in this particular piece.  

  • MattymanxMattymanx Posts: 6,949

    MelissaGT said:

    Well, that was easy! Happened to turn off the full-body geoshell (horizon vellus hair) and it went away! Now I know I can do two passes, one with and one without, in order to not have that show up in the final piece. 

    Having made Geo-Shell products, I can tell you that there is a corrilation between the "Mesh Offset" value (distance the geoshell is from the mesh its a copy of) and the distance of the camera from the figures.  The farther away the camera is, the higher the mesh offset value needs to be.  The default mesh offset for any geoshell is 0.1, but even that is pretty far away from the original mesh.  My own products usally start at 0.001 or 0.002 and still look fine at a distance.  Since the Vellus hair product has 0 set for dislacement minimum, i would suggest playing around with the mesh offset.  I have the vellus hair set too and I hve not run into this issue, even with back lighting, and I always use HDRIs.

     

    btw, what version of Daz Studio are you rendering in? 

  • AndrewJJPAndrewJJP Posts: 720

    MelissaGT said:

    AndrewJJP said:

    MelissaGT said:

    AndrewJJP said:

    MelissaGT said:

    Well, that was easy! Happened to turn off the full-body geoshell (horizon vellus hair) and it went away! Now I know I can do two passes, one with and one without, in order to not have that show up in the final piece. 

    I very much doubt I am telling you something you don't know, but you can turn off the shell and use the spot render tool to just render the bad bit rather than do another pass of the whole thing. I have never had any issues doing that anyway.

    Lovely pic BTW.

    Thank you! And in this case, with such heavy bloom, you can't use the spot render. As bloom is based on what is in the rendered window, a spot render will not render with the same amount of bloom as the whole scene...so they won't match up when you try to blend them together. It's not a worry for me...the 3090 should make quick work of it. 

    I have one of those too. Good aren't they!. Unfortunately. I make my pictures enormous and they still take a few hours...

    I can see how that would be an issue there, with such an extreme backlight. Is it purely an HDRI? (I watched the course you were involved with - I was listening!)

    Yeah, that's all HDRI lighting. I'm still working on putting the scene together so I haven't settled on it yet, but I do love the halo effect it produces for the mood in this particular piece.  

    Thanks, and I like that effect very much too.

  • MelissaGTMelissaGT Posts: 2,611

    Mattymanx said:

    MelissaGT said:

    Well, that was easy! Happened to turn off the full-body geoshell (horizon vellus hair) and it went away! Now I know I can do two passes, one with and one without, in order to not have that show up in the final piece. 

    Having made Geo-Shell products, I can tell you that there is a corrilation between the "Mesh Offset" value (distance the geoshell is from the mesh its a copy of) and the distance of the camera from the figures.  The farther away the camera is, the higher the mesh offset value needs to be.  The default mesh offset for any geoshell is 0.1, but even that is pretty far away from the original mesh.  My own products usally start at 0.001 or 0.002 and still look fine at a distance.  Since the Vellus hair product has 0 set for dislacement minimum, i would suggest playing around with the mesh offset.  I have the vellus hair set too and I hve not run into this issue, even with back lighting, and I always use HDRIs.

     

    btw, what version of Daz Studio are you rendering in? 

    Thank you! I will try playing with the offset.

    This is 4.20, but I also tried 4.15 for ha-ha's and had the same issue. 

    Current WIP progress...

     

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