Results 1 to 7 of 7

Thread: Primitive Light Color vs. Sample Surface

  1. #1
    Curmudgeon in Training Ma3rk's Avatar
    Join Date
    Mar 2003
    Location
    Near Beaverton, OR
    Posts
    1,106

    Primitive Light Color vs. Sample Surface

    I stummbled across this while reverse engineering a Daz asset that's misbehaving in Studio. In bringing it over to Lightwave via FBX, I'm finding a lot of "why'd they do it that way?", so still sorting some things, but 90% there. This is just one socket/globe that I'll instance into position later.

    I split the original geom up such that the filament is separate & used for a Primative Light. Once positioned, etc., I set the Light color and the objects color the same & toggled the setting. The result is subtly different and I not sure why or even where else to look. I prefer the Sampled better for this but would just like to know why the difference.

    Any ideas?

    Click image for larger version. 

Name:	UsingPrimLightColor.jpg 
Views:	78 
Size:	630.5 KB 
ID:	144392

    Click image for larger version. 

Name:	UsingSampleSurf.jpg 
Views:	71 
Size:	628.6 KB 
ID:	144393

    Click image for larger version. 

Name:	What it should look like.jpg 
Views:	70 
Size:	539.0 KB 
ID:	144394
    "Never be a cat in a cartoon. Never." Chief Wiggum

  2. #2
    Registered User MarkAH's Avatar
    Join Date
    Feb 2008
    Location
    Green Valley, AZ
    Posts
    41
    More cool stuff. I think you're going to sell me 2019...
    The docs say:
    The light can simply emanate from geometry or the Sample Surface option can be used to take into account the geometry's surfacing.
    If you use sampled surfaces, the light color and intensity act as a multiplier for the object's luminous intensity and color surfacing.

    That sounds real to me.
    What happens with real light that is. Both the same color so now you have R2 + G2 + B2
    If the bulb was colored pure red it would emit pure red. Like B and G are zero, and zero times anything is zero.
    Last edited by MarkAH; 03-13-2019 at 06:17 AM.

  3. #3
    Yeah, it's because the sampled colour is multiplied by the light colour, as as the environment light samples the environment and multiplies it by the light colour and intensity. 'sample surface' doesn't replace the colour and intensity, it multiplies it with the light, so change the light colour, or the surface colour, not both.

    If you have an asset where it's a simple solid colour, like that, you're better just sampling the geometry and adjusting the light colour and intensity to suit, as it's slower to sample the objects surface. (from testing).

  4. #4
    Curmudgeon in Training Ma3rk's Avatar
    Join Date
    Mar 2003
    Location
    Near Beaverton, OR
    Posts
    1,106
    Quote Originally Posted by Tobian View Post
    Yeah, it's because the sampled colour is multiplied by the light colour, as as the environment light samples the environment and multiplies it by the light colour and intensity. 'sample surface' doesn't replace the colour and intensity, it multiplies it with the light, so change the light colour, or the surface colour, not both.

    If you have an asset where it's a simple solid colour, like that, you're better just sampling the geometry and adjusting the light colour and intensity to suit, as it's slower to sample the objects surface. (from testing).
    Ah. So they work in combo of sorts & not independantly.
    "Never be a cat in a cartoon. Never." Chief Wiggum

  5. #5
    Goes bump in the night RebelHill's Avatar
    Join Date
    Nov 2003
    Location
    jersey
    Posts
    5,668
    Yes... in the same way that diffuse value, and diffuse colour are kind of interchangeable...

    https://www.youtube.com/watch?v=I9YONXWhMxQ

    Light colour and light value are too. You can think of the light colour as a kind of intensity value with separate controls for R, G, and B if you like (which is then multiplied by the main intensity scalar).
    LSR Surface and Rendering Tuts.
    RHiggit Rigging and Animation Tools
    RHA Animation Tutorials
    RHR Rigging Tutorials
    RHN Nodal Tutorials
    YT Vids Tuts for all

  6. #6
    Registered User MarkAH's Avatar
    Join Date
    Feb 2008
    Location
    Green Valley, AZ
    Posts
    41
    It's all getting so nicely scientific.
    You know, those newer incandescent bulbs are generating light with tungsten.
    But they also have a phosphorescent coating that generates light when excited by the energy from the tungsten filament.
    So you would start with the color temperature of tungsten and make the surface the color of whatever coating is used.
    There's different ones you could choose, like soft white etc.
    In that case just make the glass polys the tungsten primitive light with the phosphorescent surface color.
    And then you'd have the most realistic lightbulb in virtual space.

    Now it's LED lights and you have to get the color temperature of the LED, and I think they still have a phosphorescent coating.
    I like the daylight ones. So I could have the most realistic LED daylight bulbs in my own virtual space.
    Yeay! I'm almost ready to go for it.

  7. #7
    Remember Wade's Avatar
    Join Date
    Feb 2003
    Location
    Cypress Texas
    Posts
    1,383
    Very nice - I look forward to seeing the finished piece. Please do share when done.
    Shuttle XPCVista 64 bit /Core2Extreme x9650 3.00GHz 8GB GeForce 8800 GTS 512 Cintiq 21UX
    Dell 24" LCD Dell XT2 Tablet /Win 7 32 Bit /Core 2 duo SU9600 1.6 GHz 3GB / Mobil Intel 4500MHD

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •