Studio Photometric lights 101, Iray and 3delight.

ZarconDeeGrissomZarconDeeGrissom Posts: 5,361
edited April 2015 in The Commons

There are a few explanations around as to just what a Photometric lights is, yet some finer details I was not able to locate, so I ended up spending the evening running test renders. To find out just what that Geometry thing was all about, and why it didn't appear to have any effect in one render engine, and made drastic improvements to others.

The Photometric lights in Studio 4.8, don't entirely appear to function as I had initially thought. While in Iray, they are very much Photometric, yet in 3delight, they don't appear to have much more functionality then the regular menu lights. And thus my initial thought of making a light rig for both engines is not exactly possible. Tho threw experimentation, I think I have an idea to try, tho first, what did I discover.

Light level controls, That phrase holds true for the Photometric lights as for other lights in Studio. “Lumen” control is for Iray, and the “Intensity” control is for 3delight.
http://www.daz3d.com/forums/viewreply/784881/
The Intensity control, is fairly close to that of the DzLights in 3delight.

Geometry, is only for Iray. The “Shadow Softness” under “Shadow” is the only equivalent to Geometry in 3delight. I only have guesses as to why the visible in the render light is not also in 3delight with Photometric lights, and the illumination patron is drastically different.

Hight (Diameter), and Width. This is in CM (Centimeters). It only controls the size of the 'Geometry' emitting light in Iray. It dose NOTHING in 3delight.

Two Sided (On/Off), with a sphere it is kind of pointless, unless your inside the sphere I guess, haven't tried it. With Spotlights, it appears to do nothing at all in the current Beta. That may or may not change.

Now a quick set of test renders that I had gone threw to illustrate just how different the lights behave in Iray and 3delight. The scene is quite simple. We are inside a 40 foot cube, with a one-foot cube in the center of the floor. A Photometric Spotlight is almost touching one side of the cube (so I could see if the Geometry settings were doing anything). Just over the back left corner of the cube, I added a Photometric point-light after my first set of tests.

One note I do have as well, from the single light render in Iray. It appears that direct light fills in quicker then indirect light with Iray. This may explain why so many different scenes have such drastically different render times to reach a similar 'Convergence'.

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Post edited by ZarconDeeGrissom on
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Comments

  • ZarconDeeGrissomZarconDeeGrissom Posts: 5,361
    edited April 2015

    So, some more notes, and that thought, that was a thought.

    Turning the 'Intensity' down to zero, appears to turn off the Photometric light in Iray. So much for that though.

    If the outside cone on the spotlight is small, and your outside of the cone in-front of the light, the 'Render Emitter' becomes invisible in Iray???

    As for the thought. UberArea lights don't emit light in Iray, and vise versa with the Iray emissive surface. Now the Photometric 'Render Emitter' only functions in Iray, and thus will not block a UberArea light in 3delight. So IF it is possible for a Photometric spotlight with a rather large geometry, to only be visible in Iray renders, and not cast any light at all in 3delight, then it may be possible for me to make a room I can go back and forth without allot of hassle. Unfortunately the 'Intensity' control dose appear to effect the light in Iray, to what extent, I don't know yet.

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    Post edited by ZarconDeeGrissom on
  • Richard HaseltineRichard Haseltine Posts: 59,407
    edited December 1969

    Iray lights behave like real lights - if you can see them, they will cast light, if not, not. I would hold off on trying to configure parallel light sets - we know from the change log that we will be getting lights that are usable in both, though presumably the settings will still not be identical given the way the two engines work.

  • ZarconDeeGrissomZarconDeeGrissom Posts: 5,361
    edited December 1969

    Iray lights behave like real lights - if you can see them, they will cast light, if not, not. I would hold off on trying to configure parallel light sets - we know from the change log that we will be getting lights that are usable in both, though presumably the settings will still not be identical given the way the two engines work.
    OK, dully noted, and I also guess some of the behavior of the lights, is still in the works.

    I figured I should post something, as it took me a few hours of test renders to figure out the beginnings of what is going on (After getting an Iray capable card), and I didn't want others to have to go threw the same thing.

    That, and I needed something to work with, so I could look at hair and skin settings. I even hesitate in saying I think I found a work around, as I think it was unintentional.

    With Beta 4.8.0.9, The "Intensity" control at Zero, causes the light to turn off in Iray and 3delight. However an "Intensity Scale" of 0.0% dose indeed make the light work in Iray, and disappear in 3delight (3DL). Perfect for a makeshift fill in for the Uber Area light soft-boxes (the 40 foot light panels in my test chamber). This for the time being, allows me to do spot-renders in 3DL, and rough and final renders in Iray, without fussing with a dozen individual lights every time. I do expect that to change, as it appears to be taking advantage of a possible glitch or a few, in the light settings.

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  • Digital_TouchDigital_Touch Posts: 169
    edited December 1969

    So, photometric light using spotlight basically similar to mesh light, but with way lot faster render time then mesh light.
    Am i right to assume like that?

  • ZarconDeeGrissomZarconDeeGrissom Posts: 5,361
    edited May 2015

    So, photometric light using spotlight basically similar to mesh light, but with way lot faster render time then mesh light.
    Am i right to assume like that?

    Sort of. They work in 3delight and Iray, so that is part of the answer and complexity to your question.

    In 3delight, there is some stuff built in that is way faster them the 'Shader lights' (Code/program that runs outside of 3delight, sort of). The basic menu lights (not the photometric ones) use the stuff built into 3delight, and are much faster (to the best of my limited knolage). I don't know IF, the photometric lights do the same, or are based on 'External code' that can be much slower.

    Iray is completely different, and it dose not care what the light source is, it calculates how the light bounces around regardless of light type. So the complex answer there is it completely depends on how complex the scene is more then the lights some times, other times the lights may slow things down. It is completely different from how 3delight treats lights.

    Why.
    3delight only calculates the brightness of surfaces directly illuminated by lights. It dose not have code (in Daz Studio at least) to calculate 'Ambient light' bounced around a scene, so that must be faked with something like UE2 (Uber Environment 2). The plus to doing things this way, is it is extremely fast and the render times are more based on light setup and render settings, rather then the geometry of the scene.

    Iray actually calculates light bouncing around to do the 'Ambient light', so the complexity of the scene directly effects render times, along with light source setup complexity and render settings.

    Other thoughts. point vs surface. That is somewhat simpler for both engines.

    Point. Light only needs to be calculated starting from a point, and that is rather simple.

    Surface. Every point on the surface sends light out in all directions, so it is like having a surface made up of almost an infinite number of point lights.

    So, I don't think a Surface shader and a Photometric light set to the same size, would render significantly faster or slower in Iray. The surface size ("Geometry" settings) dose not work in 3delight, so that is still done with the 'Softness' setting in shadows (From a single point).

    I hope that helps some.

    Post edited by ZarconDeeGrissom on
  • j cadej cade Posts: 1,542
    edited December 1969

    @digital touch Not technically, but in practice yeah pretty much

    In my experience setting the Iray light to a rectangle of the same size as the equivalent mesh light in 3delight, Iray is significantly faster. (I used to use meshlights in 3delight all the time, and I never had anything render in less than 30min, and that included test renders). Other bright side, as far as I know mesh lights in 3delight don't include specular, or at least they didn't last time I used them.

  • ZarconDeeGrissomZarconDeeGrissom Posts: 5,361
    edited May 2015

    Kamion99 said:
    @digital touch Not technically, but in practice yeah pretty much

    In my experience setting the Iray light to a rectangle of the same size as the equivalent mesh light in 3delight, Iray is significantly faster. (I used to use meshlights in 3delight all the time, and I never had anything render in less than 30min, and that included test renders). Other bright side, as far as I know mesh lights in 3delight don't include specular, or at least they didn't last time I used them.

    Partly because of that point (single point) vs surface (many points) calculation thing. Also to my limited knowledge, ALL of the surface lights for 3delight are 'Shaders' and do not us much if anything built into 3delight to speed up the maths of light rays spreading out from the light.
    (EDIT)
    Also, for me, 3delight is way faster then Iray. Simply because my CPU is still much faster then my graphics card. That is the other thing that makes renders faster or slower in Iray, how good your graphics card(s) are/is.
    Post edited by ZarconDeeGrissom on
  • j cadej cade Posts: 1,542
    edited December 1969

    Kamion99 said:
    @digital touch Not technically, but in practice yeah pretty much

    In my experience setting the Iray light to a rectangle of the same size as the equivalent mesh light in 3delight, Iray is significantly faster. (I used to use meshlights in 3delight all the time, and I never had anything render in less than 30min, and that included test renders). Other bright side, as far as I know mesh lights in 3delight don't include specular, or at least they didn't last time I used them.

    Partly because of that point (single point) vs surface (many points) calculation thing. Also to my limited knowledge, ALL of the surface lights for 3delight are 'Shaders' and do not us much if anything built into 3delight to speed up the maths of light rays spreading out from the light.

    No argument there, but what the person was asking was were the Iray lights set to a shape were faster than a 3delight meshlight, to which the answer is an emphatic yes. Even though both are are emanating from many points.

  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    Kamion99 said:

    No argument there, but what the person was asking was were the Iray lights set to a shape were faster than a 3delight meshlight, to which the answer is an emphatic yes. Even though both are are emanating from many points.

    And I'll have to quibble on that point...

    Using the UberArea light then, yes, I'll agree. But using a different area light shader, there is less difference. In fact, the DzArealight (it's a ShaderBuilder example that you'll need to compile to use...just open the ShaderBuilder tab, go to Light and find it, then rt-click and Compile Network) is about 2x fast as the Uber in almost everything I've tried with it. And if you import other area light shaders, they can be even faster. Also, enabling the Progressive render, in 3DL (to turn on the raytrace 'hider') will speed many things up, even more.

    Quick test.
    UberArea...9 secs
    DzArea 3 secs

  • SpitSpit Posts: 2,328
    edited December 1969

    What is the 'raytrace "hider"'?

  • Digital_TouchDigital_Touch Posts: 169
    edited May 2015

    @zarcondeegrissom and Kamion99
    Thank you for the information, really helped a lot. I have AMD phenom quad core 2.3 ghz and gtx 660. I guess my GPU way lot better than my CPU.
    Planning to buy gtx 980 just for iray, if only i have the money.... lol
    It's totally worth it to upgrade my PC just for iray.

    Post edited by Digital_Touch on
  • evilded777evilded777 Posts: 2,283
    edited December 1969

    Do other 3Delight light shaders (such as DZArea) produce specular? Or are they diffuse only?

    I know the peculiarities of UberArea... its not supposed, but it seems to as long as you are not using a GI solution.

  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    Spit said:
    What is the 'raytrace "hider"'?

    In 3Delight terms the 'hider' is a particular renderer.

    There's the raytrace hider, which is rather new; the 'hidden' hider (the original REYES rendering) and the REYES + raytracing (not sure what that one is called). And no, I have no idea why it's called that...

  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    Do other 3Delight light shaders (such as DZArea) produce specular? Or are they diffuse only?

    I know the peculiarities of UberArea... its not supposed, but it seems to as long as you are not using a GI solution.

    Yes, the DzArea light does specular...but doesn't do shadows.

  • RicoRico Posts: 6
    edited December 1969

    @zarcondeegrissom, @mjc1016, you can tell me where to find the photometric lights?

    I searched the create menu, but they are just ordinary lights. By using these normal lights, on the parameters of these normal lights a tab of photometric appears, and that I can edit and Lumen and temperature; but it is a normal light, it is not called, for example, photometric spot light, spotlight alone.

    It is the same type of light, or it will not work the same? ...It has occurred for an upgrade?

    You can clearing that, please?

    Pd: sorry for Google's english :P

  • evilded777evilded777 Posts: 2,283
    edited December 1969

    The light typeswere combinedbefore the Public release, so you will only see the spotlight and the one (actually two countining linear) point light in the create menu. They work differently depending on which render engine you have selected in your ended settings.

  • Oso3DOso3D Posts: 14,023
    edited December 1969

    That's one thing that made me laugh with Iray... people were complaining that it was 'slower.'

    Those people evidently had not been using meshlights, because ye gods...

  • j cadej cade Posts: 1,542
    edited June 2015

    That's one thing that made me laugh with Iray... people were complaining that it was 'slower.'

    Those people evidently had not been using meshlights, because ye gods...


    Or IDL. As someone who used IDL in 3delight from time to time, Its not even close how much faster Iray is (I'm pretty sure I once tried a render with a meshlight, IDL and SSS all in one render, I'm pretty sure that if I had let it keep rendering it would still be going today.) I know that there are some faster alternatives in the 3delight thread, but even then I think Iray is probably faster and I don't have to worry about whether a light casts specular or not.

    Put another I've yet to have a 18hr render in Iray, and those were pretty par for the course for me in 3delight

    Post edited by j cade on
  • kyoto kidkyoto kid Posts: 32,548
    edited June 2015

    ...Figure 1. 3DL with HDRI (UE) and 5 frame motion blur = 16 hrs 30 min.

    ...Figure 2. Iray with HDRI, a large set, "mist cube", and wet surfaces = 4 hrs 20 min.

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  • RicoRico Posts: 6
    edited June 2015

    The light typeswere combinedbefore the Public release, so you will only see the spotlight and the one (actually two countining linear) point light in the create menu. They work differently depending on which render engine you have selected in your ended settings.

    So, if I use Iray render as render engine, the lights will always photometric?

    In Youtube I have seen That, for example, you can create a photometric point light, and that was his name:

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    Post edited by Rico on
  • RicoRico Posts: 6
    edited June 2015

    The light typeswere combinedbefore the Public release, so you will only see the spotlight and the one (actually two countining linear) point light in the create menu. They work differently depending on which render engine you have selected in your ended settings.

    So, if I use Iray render as render engine, the lights will always photometric?

    In Youtube I have seen That, for example, you can create a photometric point light, and that was his name:


    But in my Daz these is not posible, but then I can edit that normal light:

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  • scorpioscorpio Posts: 6,942
    edited December 1969

    The beta had the Iray Photometric lights as separate items from the DS lights, but the release version combined them.

  • RicoRico Posts: 6
    edited December 1969

    The beta had the Iray Photometric lights as separate items from the DS lights, but the release version combined them.

    Thank you very much, this is what I wanted to clarify. I thought maybe I was missing something by download.

  • MarshianMarshian Posts: 1,311
    edited September 2015

    True- The shadows soften as the photometric light geometry scale increases- there is also a slight increase in render time and grain.

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  • kyoto kidkyoto kid Posts: 32,548

    ...in a night scene I am working on I used one Photometric distant light as teh "moon" as I also had an HDRI for the sky background (which blocks out he Iray "sun").  When I attempted to use additional photometric lights (a point and spot), they would show up in the viewport fine, but had not effect in the final render.  Not sure what is causing this.

  • RogerbeeRogerbee Posts: 4,460

    Hmm, this is a thread I'll be paying attention to now. Yep, I've started with Iray!!

    Here's what I've done so far, pretty default save for an HDR freebie by Dumor3D that I got with DS Creative.

    CHEERS!

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  • ToborTobor Posts: 2,300
    Marshian said:

    True- The shadows soften as the photometric light geometry scale increases- there is also a slight increase in render time and grain.

    You can compensate for much of this by increasing the light output. Notice how the sphere, and the scene in general, get darker as the light area becomes larger. When you expand the area of an area light, the lumens are constant for the surface, not per square centimeter. With a larger area, the same amount of lumens light a larger scene. Therefore, the light incident apon any particular spot in tre scene goes down. We know that Iray "likes light," and convergence is assisted when there are sufficient photons to calculate against.

    You won't get back the render speed entirely by compensating for the change in incident light, though, as in general softer shadows require more calculations.

  • ZarconDeeGrissomZarconDeeGrissom Posts: 5,361
    edited September 2015
    Rogerbee said:

    Hmm, this is a thread I'll be paying attention to now. Yep, I've started with Iray!!

    Here's what I've done so far, pretty default save for an HDR freebie by Dumor3D that I got with DS Creative.

    CHEERS!

    HDR freebie??? The Photometric lights work with HDR maps!? or are you using the Photometric lights with an HDR sky-dome? Or are you hinting that you haven't had a chance to play with Photometric lights yet.

    They use to be called "Photometric lights" way back in the beta. I think they changed it to be the default 'menu light' when Iray is selected in the render tab (or something like that).

    Marshian said:

    True- The shadows soften as the photometric light geometry scale increases- there is also a slight increase in render time and grain.

    Yea, the complexity of the environment affects render times just as much as the geometry of the lights (Round or rectangle geometry on the lights. size placement, etc). The effects may be similar to the render times vs geometry complexity/size of 'emissive' surfaces. Along with exactly what Tobor posted above.

    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.

    Post edited by ZarconDeeGrissom on
  • kyoto kid said:

    ...in a night scene I am working on I used one Photometric distant light as teh "moon" as I also had an HDRI for the sky background (which blocks out the Iray "sun").  When I attempted to use additional photometric lights (a point and spot), they would show up in the viewport fine, but had not effect in the final render.  Not sure what is causing this.

    That is a good one. I haven't had Photometric lights just not work, tho my first attempts were extremely dark as I had them set way to dim with the 'lumen' control.

    Also, is there a control for the lights "Illumination" to be 'on' in the render (it may have somehow turned it's self off). I know when I click the eye-ball in the scene tab for a light to make it vanish from view, it turns the light off in the render as well (Iray and 3delight). If your trying to make the light be 'phantom' of sorts, the "Render emitter" may possibly do that, I think, or it may also just turn off the light as well.

  • mjc1016mjc1016 Posts: 15,001
     

    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...

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