Iray Question: Make a Sphere Emit Light?

NyghtfallNyghtfall Posts: 417
edited December 1969 in The Commons

I'm using a primitive sphere to learn how to work with Iray surfaces, and having trouble getting it to emit light after applying the Emissive shader to it. It appears as a matte brown in both Iray draw mode and when rendering.

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Comments

  • nicsttnicstt Posts: 6,402
    edited December 1969

    Content Library > Shader Presets > DAZ Uber

    Select the item (sphere) and select it in surfaces tab > double click the !Iray Uber Base > then the Emissive shader in the same place as !Iray Uber Base.

    Then you can adjust Emission Temp and Luminance in the surfaces tab for the colour and 'power' of the light.

    Temperature needs to be about 6500 for typical lighting. above and below the 6500 changes it towards red or blue. Lower for red iirc.

    Luminance - change from 5000 by a power of 1, 2 or 3: 1, 2 or 3 zeroes - or whatever works for your scene; or you could change the luminance units from cd/m^2 to kcd/m^2

    cd is candellas, and the k indicates a 1000 of em.

  • NyghtfallNyghtfall Posts: 417
    edited June 2015

    So, I have to apply the Uber Base before the Emissive shader?

    EDIT: No dice. Just tried it, and the sphere still renders matte brown, even after increasing Luminance to 6500.

    Post edited by Nyghtfall on
  • nicsttnicstt Posts: 6,402
    edited June 2015

    Nyghtfall said:
    So, I have to apply the Uber Base before the Emissive shader?

    EDIT: No dice. Just tried it, and the sphere still renders matte brown, even after increasing Luminance to 6500.

    Make sure you're selecting it in the scene and in surfaces:

    EDIT: and that you adjust temperature and colour

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    Post edited by nicstt on
  • AJ2112AJ2112 Posts: 983
    edited December 1969

    You have to really crank up Luminance, I alway's begin at 45000

    Nyghtfall said:
    So, I have to apply the Uber Base before the Emissive shader?

    EDIT: No dice. Just tried it, and the sphere still renders matte brown, even after increasing Luminance to 6500.

  • DinoVincentDinoVincent Posts: 322
    edited June 2015

    Make sure your render settings are set to "Done and Scene" or "Scene only" and not "Dome Only".

    Don't be afraid to put some big numbers into luminance either.

    AwesomeFBs suggested starting point is a good one.

    Post edited by DinoVincent on
  • Peter WadePeter Wade Posts: 985
    edited December 1969

    Nyghtfall said:
    So, I have to apply the Uber Base before the Emissive shader?

    EDIT: No dice. Just tried it, and the sphere still renders matte brown, even after increasing Luminance to 6500.

    I'm not very experienced with IRay but I've had to set luminance values into the hundreds of thousands to get any visible light casting, either that or set the tone mapping to very long exposure/wide aperture settings.

  • Richard HaseltineRichard Haseltine Posts: 42,025
    edited December 1969

    Nyghtfall said:
    So, I have to apply the Uber Base before the Emissive shader?

    EDIT: No dice. Just tried it, and the sphere still renders matte brown, even after increasing Luminance to 6500.

    I'm not very experienced with IRay but I've had to set luminance values into the hundreds of thousands to get any visible light casting, either that or set the tone mapping to very long exposure/wide aperture settings.

    You can change the units kilo candelas to make the numbers more manageable.

  • MarcCCTxMarcCCTx Posts: 545
    edited June 2015

    To change the color, you need to change the Emissive Temperature. Default is way too cold. Change to around 6500 for the blue white temp you're probably expecting.

    First: Here's 6500, with 3 zeros added to Luminance.
    Second: 6500, with a single zero added to Luminance.

    Edited: for grammar and accidental snarkiness.

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  • RarethRareth Posts: 1,458
    edited December 1969

    don't forget to turn off the Headlamp on the camera if trying for a low light scene

    Also it may be more intuitive to adjust the Tone Mapping settings in the Render Editor tab rather than to keep increasing the light settings.
    this also works better with scenes with lots of individual lights/emissive meshes as you can just easily adjust how sensitive the camera is to the lights.

    for example, here is a basic scene, 15m Cube Rubber matte with RGB all set to 128, glossy reflectivity at .25

    the Sphere has the default emissive shader applied with NO changes to settings

    Head Lamp is off

    I did 4 renders, first used the default tone mapping settings, 2nd f/stop was changed to 4, 3rd f/stop 4, shutterspeed 60, 4th f/stop 4, shutter speed 60 and Film iso 200
    they probably didn't post in order, so settings were added to the images.

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  • D.RobinsonD.Robinson Posts: 252
    edited June 2015

    Don't forget you can change the luminance units on the drop down menu below the luminance value(i dont even mess with the luminance slider i keep it at 5000) to make it easier to understand. My self i like to set the luminance unit to watts..i prefer this because i understand the idea of wattage of a bulb. When you change to to watts another setting will appear below it it defaults to 15 watts...which is really weak unless its a very small enclosed space. As an example this is a render i did a few days ago.

    The ambient light in the scene is from the HDRI but the main light on the subject is a sphere with emission shader applied. Just off camera to the right. Its set for 1200 watts, and the temp. is set to 5500 to better simulate the sun position and haze of the HDRI.

    Daniel

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    Post edited by D.Robinson on
  • Oso3DOso3D Posts: 11,953
    edited June 2015

    What I usually do is add a few zeroes at a time until the light is noticeable, and then fine-tune from there.

    I think, and I'm not 100% on this, that if you SubD the object, it might work better as an emitter.

    Post edited by Oso3D on
  • D.RobinsonD.Robinson Posts: 252
    edited December 1969

    While on the subject of emissive primatives. The cool thing about them is you can manipulate the primitive to make interesting light effects.

    This render i did uses the sphere as well but the sphere is actually in the scene over her left hand. But what i did was scale it down to .5% so its microscopic but it still radiates the same light as the bigger sphere. It was a neat trick i stumbled on by accident.


    http://www.daz3d.com/gallery/#images/71649


    Daniel

  • Oso3DOso3D Posts: 11,953
    edited December 1969

    As an aside, emission on any object is awesome for sprucing up old sets/scenes, with lamps/fires/etc. You can find those fire surfaces and just make them emit, rather than playing around with light placement.

  • Peter WadePeter Wade Posts: 985
    edited December 1969

    As an aside, emission on any object is awesome for sprucing up old sets/scenes, with lamps/fires/etc. You can find those fire surfaces and just make them emit, rather than playing around with light placement.

    This is very true. I have bought DzFire's Real Lights for Iray, yiou just have to apply them to the right materials.

    Here is a scene I did using Stonemason's Dark Star set. The only lighting in the scene is coming from mesh lights. I just looked for materials with "light" in the name. There are three in this set, two are white so I made them fluorescent and one is red so that got Red Neon. I set the environment to Scene Only and switched off the headlight. I had expected to have to add more lights after the first attempt but I like the look of it with just these three lights.

    One thing to watch out for, if the only lights you have are mesh lights I don't think the headlight automatic switch off works so you have to set it to "never".

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  • NyghtfallNyghtfall Posts: 417
    edited December 1969

    Thank you all for the replies. Much appreciated.

    dubby30 said:
    Don't forget you can change the luminance units on the drop down menu below the luminance value(i dont even mess with the luminance slider i keep it at 5000) to make it easier to understand. My self i like to set the luminance unit to watts..i prefer this because i understand the idea of wattage of a bulb. When you change to to watts another setting will appear below it it defaults to 15 watts...which is really weak unless its a very small enclosed space. As an example this is a render i did a few days ago.

    This especially helped. I'm also much more familiar with wattage than luminance.

  • The Blurst of TimesThe Blurst of Times Posts: 429
    edited June 2015

    If Watts work for you, great. I eventually went back to lumens because Watts measure electricity applied to light. This makes sense in a filament. However, when I tried applying Watts to different primitives of varying surface area, I found Watts to be less than reliable because the light emission never seemed to scale logically with the change to surface area.

    Using a lumen output per surface area measurement just made for more sense to me. YMMV, though.

    Post edited by The Blurst of Times on
  • NyghtfallNyghtfall Posts: 417
    edited December 1969

    I eventually went back to lumens because Watts measure electricity applied to light. This makes sense in a filament. However, when I tried applying Watts to different primitives of varying surface area, I found Watts to be less than reliable because the light emission never seemed to scale logically with the change to surface area.

    Using a lumen output per surface area measurement just made for more sense to me..

    That's actually an excellent point. Thank you. I'll definitely keep in mind.

  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    If Watts work for you, great. I eventually went back to lumens because Watts measure electricity applied to light. This makes sense in a filament. However, when I tried applying Watts to different primitives of varying surface area, I found Watts to be less than reliable because the light emission never seemed to scale logically with the change to surface area.

    Using a lumen output per surface area measurement just made for more sense to me. YMMV, though.

    Or think of it this way...just how bright would a 100W LED lamp be?

    Considering that industrial lasers are not usually in that range (much lower...) and consumer grade LED bulbs fall in the 15W and under range...

  • Peter WadePeter Wade Posts: 985
    edited December 1969

    If Watts work for you, great. I eventually went back to lumens because Watts measure electricity applied to light. This makes sense in a filament. However, when I tried applying Watts to different primitives of varying surface area, I found Watts to be less than reliable because the light emission never seemed to scale logically with the change to surface area.

    Using a lumen output per surface area measurement just made for more sense to me. YMMV, though.

    I assume Watts must be based on the light output of a particular type of light, probably an old style tungsten filament bulb. Other types of lights produce different amounts of light from the same number of watts.

    Lumens is a technically more correct measurement but most people are not familiar with it. When I'm looking for a replacement for one of those low energy fluorescent things I look at the bit that says what wattage old style bulb it is equivalent to rather than it's actual wattage.

  • SpottedKittySpottedKitty Posts: 5,751
    edited December 1969

    Nyghtfall said:
    I'm using a primitive sphere to learn how to work with Iray surfaces, and having trouble getting it to emit light after applying the Emissive shader to it. It appears as a matte brown in both Iray draw mode and when rendering.

    Go into the Render Settings pane and click on the Tone Mapping section. The default settings are for something like a nice bright cloudless sunny day (possibly in the Sahara, at high noon) — the sphere looks dull and brown because these settings are much too "fast" for the amount of light in your scene. You will need to tweak the values until you get something that "looks right".

    Note that the three most important parameters need a bit of photographic knowledge:-

    * Shutter Speed is an inverse value; the default of 1/128 of a second is very fast. Bring the value right down for a slower "exposure". It's not unusual for me to end up using a value of 1/8, 1/4 or even 1/2.
    * F/Stop is the size of the aperture letting light into the camera; normal real camera lenses use settings of f1.2 for fully open to f22 for a tiny little pinprick.
    * Film ISO is the "speed" rating of the film; 100 is an average type for most outdoor photos. Lower speeds (64, 32 or even lower) need more light, and higher speeds (200, 400, 800 or more) need less light to produce the same brightness in the render.

    (Don't worry too much about the weird numbers, they come from photography, where each "step" in the values doubles or halves the amount of light falling on the film. Your D|S camera isn't a real one, so you don't need to limit yourself to the traditional values.)

  • zombietaggerungzombietaggerung Posts: 1,095
    edited December 1969

    As an aside, emission on any object is awesome for sprucing up old sets/scenes, with lamps/fires/etc. You can find those fire surfaces and just make them emit, rather than playing around with light placement.

    This is very true. I have bought DzFire's Real Lights for Iray, yiou just have to apply them to the right materials.

    Here is a scene I did using Stonemason's Dark Star set. The only lighting in the scene is coming from mesh lights. I just looked for materials with "light" in the name. There are three in this set, two are white so I made them fluorescent and one is red so that got Red Neon. I set the environment to Scene Only and switched off the headlight. I had expected to have to add more lights after the first attempt but I like the look of it with just these three lights.

    One thing to watch out for, if the only lights you have are mesh lights I don't think the headlight automatic switch off works so you have to set it to "never".

    I hate to bump an old topic, but you just solved my hair-pulling, insomnia inducing, week long, frustrating lighting problem in iray. SO thank you!!! And hopefully this will help someone else as well!

  • What's the best way to get this effect (see glowing toy image attached).  I want a glow, but also retain some details in the object. 

    This (see render sample) is the best I've been able to achieve, by simply raising the metallicity level all the way.  

    I suspect it would take a special shader and require the object to have a UV map to get the same effect as the toy image. 

     

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  • Is the toy a photo? Whether or not it is, are you sure it's glowing in its own right and not just translucent?

  • Is the toy a photo? Whether or not it is, are you sure it's glowing in its own right and not just translucent?

    Good questions. It is a photo, and I believe it is is a soft white semi-translucant figure with a     led light inside. 

     

    I got a little closer to what I want by just lighting the object normally, and then changing the color of the emission to a very dark green, and adjusting the temperature.   

     

     

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  • Hey that's like bit from Tron!

  • It is a photo, and I believe it is is a soft white semi-translucant figure with a     led light inside.

    I think you gave yourself the answer,  put a small point light inside the center of your model and adjust the luminance and temperature until you get the desired effect. 

  • FishtalesFishtales Posts: 2,937
    edited December 2017

    I had a try but I don't think it is what you are looking for.

    I've attached the shader preset for you to try.

    Click on image for full size.

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    duf
    duf
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    Post edited by Fishtales on
  • Fishtales, yes that's pretty close.  Thank you! 

  • FirstBastionFirstBastion Posts: 4,104
    edited December 2017

     

    Post edited by FirstBastion on
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