Studio Photometric lights 101, Iray and 3delight.

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  • mjc1016 said:
     

    Iray is not 'faking' ambient light akin to using UE2 in 3delight, it's actually calculating it. The more complex the scene, the longer it will take to calculate.

    UberEnvironment is NOT 'faking' ambient light...

    O.K. then I understood it wrong, oops. I thought it based illumination of a surface based on distance to other surfaces or something simple like that. There is a few deferent modes tho, and some render faster then others.

  • mjc1016mjc1016 Posts: 15,001
    mjc1016 said:
     

    Iray is not 'faking' ambient light akin to using UE2 in 3delight, it's actually calculating it. The more complex the scene, the longer it will take to calculate.

    UberEnvironment is NOT 'faking' ambient light...

    O.K. then I understood it wrong, oops. I thought it based illumination of a surface based on distance to other surfaces or something simple like that. There is a few deferent modes tho, and some render faster then others.

    That's an ambient occlusion calculation...and Iray does the same thing (it's part of the internal code of Iray...in fact that calculation is pretty much internal to most renderers).

    The code used to calculate the global/ambient light in UE2 and just about all other 3Delight shaders is 'real'.  So, yes, using a 'real' GI/ambient light shader in 3DL is not 'faking' it.  That's where things like '3DL can't do SSS and therefore Studio come from.

  • ZarconDeeGrissomZarconDeeGrissom Posts: 5,402
    edited September 2015

    ah, yea. This is in 3delight... If Ambient was calculated on the amount of light reflected off of other surfaces... This simple test would not have failed, lol.

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  • ZarconDeeGrissomZarconDeeGrissom Posts: 5,402
    edited September 2015

    It should have ended up more like this photo, using a mechanics mirror, lol.

    And to drive it home. A far more complex version of the mirror-pillar test, with the rings on the light fixture, in Iray. The original 3delight one is here.

    http://www.daz3d.com/gallery/images/42065

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  • mjc1016mjc1016 Posts: 15,001

    And what setting did you have UE2 on? 

    And what is that spot light? 

  • It starts about here.

    http://www.daz3d.com/forums/discussion/comment/698931/#Comment_698931

    I tried all the different lights at the time with the same exact results. I have tried all the UE2 modes, and I tried AoA, Omni, and daz default on that pillar. The point is, that ambient light, is the light bouncing off other things. 3delight dose not do that. There is a trick with cameras, and spaghetti land to fake it, however it is limited to surfaces viewable to a camera, so complex shapes (like that light fixture) simply can not be done with 3delight 'Caustics'.

    I also bounced it off the folks in the 3delight thread.

    http://www.daz3d.com/forums/discussion/comment/711818/#Comment_711818

  • mjc1016mjc1016 Posts: 15,001
    edited September 2015

    And Kettu summed it up pretty well...it's not that it is 'faked'...it's that the shaders used in studio don't give access to the functions needed to display it.  The problem is not the capabilities of  3DL, but rather the shorcomings of the default DS shaders.

    And your 'spaghetti-land' well, guess what...that is the easiest way to make a shader that IS capable of accessing the full power of the renderer, things that  Lux and Iray are accessing by default (because they are NOT using shaders...this is all hard coded into them).

    And something I've never been able understand...why don't the standard DS cameras have caustics built in?  Why is a 'caustic camera'  needed?

    Post edited by mjc1016 on
  • edited November 2015

    since this is a 101 for photometric lights, then I'd like to ask about something that I am running into. Here's two attachments, the first being the Iray render that I was trying to use a spotlight on, and the second is that exact same scene but using the 3Delight render.

    Can I ask of what it is I am doing wrong? :( I want to be able to make my own lights so that my scenes won't look like the same thing with the pre-made lights I have, but I keep on running into this problem, and I would like it solved, if possible. :( I showed what the settings were with the spotlight to try to help with showing on what's going on. The spotlight was made using the active viewport transforms so that it points directly at the scene.

     

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  • Gr00vusGr00vus Posts: 340
    edited November 2015

    Distance from the surface to be illuminated is very important in iray. The light falls off more quickly than in non-pbr renders. I can see a bit of illumination in the lower left corner of your iray render, maybe move your light closer to your surface and see if that helps. Also, assuming this is the only light in your scene there may not be enough light available to illuminate in the way you wish. You can either add more lights or try to adjust the render tone  mapping settings to get more light into the "lens". Higher ISO, slower/larger shutter speed and/or smaller f/stop are all possibilities in that case. As a starting point for darker indoor scenes you can try f-stop 4 to 5.6, shutter speed 1/60, ISO 400 or more.

    since this is a 101 for photometric lights, then I'd like to ask about something that I am running into. Here's two attachments, the first being the Iray render that I was trying to use a spotlight on, and the second is that exact same scene but using the 3Delight render.

    Can I ask of what it is I am doing wrong? :( I want to be able to make my own lights so that my scenes won't look like the same thing with the pre-made lights I have, but I keep on running into this problem, and I would like it solved, if possible. :( I showed what the settings were with the spotlight to try to help with showing on what's going on. The spotlight was made using the active viewport transforms so that it points directly at the scene.

     

     

    Post edited by Gr00vus on
  • edited November 2015

    I'm actually trying to set up the lights before making the textures that I want, including of making water that will glow within the scene. I switched out to be a more open form of room, and I used the Exposure value to be at 12.25, shutter speed at 1/60, F/Stop at 4.5, Film ISO at 400.

    Here's the results inside of Iray, using one point light, a distant light, and 2 spotlights, one being further back, and one just trying to see of the in general with the one being viewed with the camera. I had done a fast render with Iray, the 3Delight easily rendered in a few moments, as well.

     

    So it's definitely on the right track! :D I need to remember my photography skills from college to help with this stuffs nao. :) I will hope in being able to make the lighting I desire. Thank you very very much!

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  • If you want to match the look of point or spot lights between 3Delight and iray one requiremnt is that the 3Delight settings include decay = 2, inverse square falloff. That's how all lights (other than infinite/distnat lights) work in iray and in the real world.

  • Good point Richard Haseltine.

    Another thing I've noticed, is when the "Intensity" is changed with some lights (can't remember if that was the beta Photometric, or the post-beta ones), it will throw the Iray 'Lumens' setting off. Say if you set the 'Intensity' to less then 100% for 3delight, the Lumen setting will need to be cranked up further to get the same amount of light out of the light in Iray.

    Obviously that is only with the Photometric lights, as things like the Uber area lights (3delight only) are completely different things from the Iray Emissive shader that only works in Iray.

  • Gr00vusGr00vus Posts: 340
    edited November 2015

    You're on the right path. The tone mapping settings I gave are just a starting point, if things are still too dark/grainy you can make them more extreme to correct, add more lights, and/or up the lumens on your existing lights.

    Another thing to keep in mind with the iray spotlights - changing the scale (height, width/diameter) and/or changing the spread angle will have an impact on the percieved intensity of the light, as the same amount of light will be spread out over a different volume. So if you increase the scale (default is 10 x 10 I believe) or the spread angle (default is 60 degrees), you will need to increase your lumens if you want to keep the same light intensity over the larger volume. This is one reason people like using the mesh/emissive object approach for lighting - the units of measurement for the light intensity (I think it's lumes per square centimeter by default) takes volume into account when using emission on an object, so changing the size of the emitter "automatically" adjusts the light outupt accordingly without you having to manually change the intensity.

    I'm actually trying to set up the lights before making the textures that I want, including of making water that will glow within the scene. I switched out to be a more open form of room, and I used the Exposure value to be at 12.25, shutter speed at 1/60, F/Stop at 4.5, Film ISO at 400.

    Here's the results inside of Iray, using one point light, a distant light, and 2 spotlights, one being further back, and one just trying to see of the in general with the one being viewed with the camera. I had done a fast render with Iray, the 3Delight easily rendered in a few moments, as well.

     

    So it's definitely on the right track! :D I need to remember my photography skills from college to help with this stuffs nao. :) I will hope in being able to make the lighting I desire. Thank you very very much!

     

    Post edited by Gr00vus on
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