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Ghost Light Kit Forum?

inquireinquire Posts: 2,252
in Technical Help (nuts n bolts)

Is there such a forum? I've searched with the Search function. If not, I'm trying to find out if the Ghost Lights can be scaled. Also, can they be rotated? And although they come with presets, can I alter the color of a light? Also, can I adjust the intensity if I want to? Perhaps someone using these lights will be able to answer my questions. Here's the product ad page: https://www.daz3d.com/iray-ghost-light-kit

Comments

  • scorpioscorpio Posts: 8,484
    inquire said:

    Is there such a forum? I've searched with the Search function. If not, I'm trying to find out if the Ghost Lights can be scaled. Also, can they be rotated? And although they come with presets, can I alter the color of a light? Also, can I adjust the intensity if I want to? Perhaps someone using these lights will be able to answer my questions. Here's the product ad page: https://www.daz3d.com/iray-ghost-light-kit

    Yes and yes and yes and yes, I've only got the Ghost Light Kit 2 but I csn't see thast the first pack is any different in how they work in general.

  • scorpioscorpio Posts: 8,484

    here's a link to the PA's threads on their ghost light sets

    https://www.daz3d.com/forums/discussion/168206/iray-ghost-light-kit-2-render-and-support-thread-commercial#latest

    https://www.daz3d.com/forums/discussion/137231/iray-ghost-light-render-and-support-thread-commercial#latest

  • CrissieBCrissieB Posts: 195

    Ghost lights are simply objects whose surface is an Iray Emissive. Select the object, then the Surfaces tab, then scroll down to the Emission Color and the settings below that. Because it's a mesh object, you can translate, rotate, and scale it just as you would any other object in a scene. Yes, the Iray Ghost Light Kit comes with presets.

    You can reset the color of a ghost light -- or any Iray Emissive -- in two ways:

    (1) Emission Color​: The default Emission Color for an Iray Emissive is pure white (RBG: 1.0-1.0-1.0). Think of this as a lighting gel. That is, set the correct Emission Temperature for your source first (see below) and then change the Emission Color only if your light source would have a colored lens or a gel mounted.

    (2) Emission Temperature​: The default Emission Temperature for an Iray Emissive is 6500K, roughly equivalent to bright sunlight. This Wikipedia article on color temperature gives you a good guideline for Emission Temperature settings (*but see note below). Lower temperatures are golder; higher temperatures are bluer. Note that this is the opposite of what we consider "warm" (reds, oranges, ambers) or "cool" (blues, purples) colors.

    (*) A note about moonlight:​ The color temperature of moonlight is actually lower than the color temperature of sunlight. But human eyes perceive blues more strongly in low-light -- the Purkinje Effect -- so moonlight and objects at night look bluer. To simulate moonlight, I set the Emission Temperature to 8000K.

    As for intensity, you can adjust that with the Luminance setting ... and here you run into real problems if you try to use the 'correct' settings. For example, a typical 60-watt compact fluorescent or LED bulb puts out about 1600 lumens, but an Iray Emissive set at 1600 lm would be pretty much useless in terms of lighting your scene. The reason is that your eye and brain do a whole lot of automatic light-adjusting, from pupil dilation to retinal persistence to the visual cortex filling in incomplete information. A camera doesn't do any of that, and DAZ Iray rendering works like a camera.

    Thus, the Luminance of your ghost lights will need to be at least 10x higher than the 'correct' setting for a given source. How much higher, exactly? Well, that depends on your Render Settings>Tone Mapping. (See this excellent tutorial by Sickleyield: https://sickleyield.deviantart.com/journal/Tutorial-Lighting-and-Tone-Mapping-In-Iray-531864617 ).

    Basically, it's trial-and-error, and it's a whole lot easier to adjust your lighting if you set your Preview to Iray Mode. If your GPU/CPU make that unbearably slow, you'll have to do trial renders. If render times are a problem, reduce the size of your test renders (say: 320x180 for widescreen). You don't need to see details; you need to see if the lighting is right.

    I hope this helps,

    Crissie

  • fastbike1fastbike1 Posts: 4,078
    edited January 2018

    @inquire

    http://docs.daz3d.com/doku.php/public/read_me/index/43797/start

    @CrissieB "(*) A note about moonlight:​ The color temperature of moonlight is actually lower than the color temperature of sunlight. But human eyes perceive blues more strongly in low-light -- the Purkinje Effect -- so moonlight and objects at night look bluer. To simulate moonlight, I set the Emission Temperature to 8000K."

    Here are some other things that can help simulate moonlight.

       Set the Tone Mapping White Point to something like 255,212,212. You want the color  "opposite" of blue white moonlight.

       Use a spotlight (or Emissive) with the color temp 8000 - 10000k for the moon

       Use a distant light for shadow cast

       Environment>Ground Shadow> 0.5 for less dense shadows

    Note: the attached file is a daylight HDRI shot and has no post-processing

     

    Izabella 7. Forest F 1.0 env map. Moonlight Dance.png
    934 x 903 - 1M
    Post edited by fastbike1 on
  • inquireinquire Posts: 2,252

    Thank you for the above comments and explanations.

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