Tips & Tricks for Iray for newbies......

1679111241

Comments

  • DAZ_SpookyDAZ_Spooky Posts: 3,100
    edited December 1969

    Zev0 said:
    Is there a way to reduce the Z-scale of the dome? when I reduce size to match scale to figure, the fisheyed lense effect is kind of strong.

    Click with right mouse button on the Render Setings tab and activate "Show hidden properties". You will than have dome widith, hight and depth sliders. Plus bunch of other hidden stuff.Switching to a Finite Dome makes those dome settings visible.
  • EmmaAndJordiEmmaAndJordi Posts: 848
    edited December 1969

    @SnowSultan and others in the 3 Pillars of Photography discussion!

    It's not that I disagree with changing those settings, it's that I knew jack about those specific things before this discussion! I've never been able to afford a DSLR and always used digital cameras that had "for dummies" settings for my texturing (or a scanner).

    I had to go look up the 3 Pillars yesterday just to understand what ISO was. In my last render I posted to the "show us Your Iray Renders" thread I did play with the aperture and ISO and improved the strength of my lights considerably (that scene was lit with two weak photometrics and a small amount of environment light).

    Definitely one cannot use the default render settings for both ISO AND photometric light strength, though. Leaving default ISO the photometrics require very high lumen values, or leaving default photometric strength values (1500 lm??) the ISO must be changed.

    Thanks a lot for your amazing video! :)

    I know some about this. These definitions and tips may not be technically exact but they are practical:

    - ISO is the reactiveness of the film. The higher, more light enters in the photography. It usually also produces noise. But not always, for example, in absence of light, a higher ISO can really decrease the noise if you get the exact proportion of ISO

    - Aperture: it's like the pupil of the eye. The more higher f number, it is more closed. Think in a pupil that is very small, it leaves less light enter into the eye, but it focuses better. The lower f number, the aperture is higher, the pupil is bigger. The background may look blurry, the subject focused, but the light on the scene is higher too.

    To get more light: increase ISO, decrease the f number (= more aperture).

    Jordi

  • SnowSultanSnowSultan Posts: 2,288
    edited March 2015

    And of course there is simple logic: why would one have to create physically implausible lights in a physicaly based rendering system? One should not have to, therefore the answer must lie elsewhere.

    Art is always a mix of science, talent and passion (remember the old masters who used to mix their own paints), this just happens to have a little more science.

    I’m arguing a position here, i have the utmost respect for you and your contributions the community, please take none of this personally


    Thank you, and of course I don't take offense; I'm just as confused about Iray lighting as the rest of us. :) Your logic describes the exact problem I've had with trying to figure out this lighting from the beginning: why are people having to crank up luminance to a billion when this is supposed to be a realistic system?


    I suppose what I'm hoping for are some basic standards in presets that will give a decent starting point for any user. For example, on this page about Exposure values, a lot of exposure values for lighting conditions are listed. If we were to all agree that 12-13 is right for outdoor scenes, 6-9 should work for illuminated nighttime scenes, and 5-8 are best for interior lighting, we could then start sharing and selling light presets based on those values.

    Has anyone tried lighting a scene with a combination of realistic light illumination values and exposure adjustment and then tried rendering the same scene with the EV set at the default of 13 and cranking up the lights to compensate? I wonder if there would be a difference in grain, bounced light, or anything else to make one method more preferable to the other.

    Post edited by SnowSultan on
  • namffuaknamffuak Posts: 2,960
    edited December 1969

    @SnowSultan and others in the 3 Pillars of Photography discussion!

    It's not that I disagree with changing those settings, it's that I knew jack about those specific things before this discussion! I've never been able to afford a DSLR and always used digital cameras that had "for dummies" settings for my texturing (or a scanner).

    I had to go look up the 3 Pillars yesterday just to understand what ISO was. In my last render I posted to the "show us Your Iray Renders" thread I did play with the aperture and ISO and improved the strength of my lights considerably (that scene was lit with two weak photometrics and a small amount of environment light).

    Definitely one cannot use the default render settings for both ISO AND photometric light strength, though. Leaving default ISO the photometrics require very high lumen values, or leaving default photometric strength values (1500 lm??) the ISO must be changed.

    Thanks a lot for your amazing video! :)

    I know some about this. These definitions and tips may not be technically exact but they are practical:

    - ISO is the reactiveness of the film. The higher, more light enters in the photography. It usually also produces noise. But not always, for example, in absence of light, a higher ISO can really decrease the noise if you get the exact proportion of ISO

    - Aperture: it's like the pupil of the eye. The more higher f number, it is more closed. Think in a pupil that is very small, it leaves less light enter into the eye, but it focuses better. The lower f number, the aperture is higher, the pupil is bigger. The background may look blurry, the subject focused, but the light on the scene is higher too.

    To get more light: increase ISO, decrease the f number (= more aperture).

    Jordi

    Just a couple of observations/notes to go with this.

    Any film with an ISO rating under 400 used indoors required a flash or a set of floodlights. ISO 400 was pretty much a minimum film speed for indoor available light photography but usually require such a large lens opening (small f-stop, like 1.2 or 2) that depth of field vanished. I did a lot of indoor slides at ISO 1600 with a camera-mount flash unit - but then you have to be careful not to over-light the subject.

  • macleanmaclean Posts: 2,134
    edited December 1969

    To continue Jordi's explanation....

    F-stop and shutter speed are closely linked on a camera. The f-stop is in the camera lens (so each lens will have its own range of f-stops) and the shutter speed is in the camera itself.

    Here's a list of a normal SLR's f-stops

    f2 - widest - lets in most light
    f2.8
    f4
    f5.6
    f8
    f11
    f16
    f22
    f32 - narrowest - lets in least light
    f64 - only found on specialist lenses
    (Each number is half the previous one in terms of how much light it lets in. f11 lets in half the light of f8)

    Camera shutter speeds
    1sec - slowest - lets in most light
    1/2
    1/4
    1/8
    1/15
    1/30
    1/60
    1/125
    1/250
    1/500
    1/1000
    1/2000 - fastest - lets in least light
    (Each number is half the previous one in terms of how much light it lets in. 1/250 lets in half as much light as 1/125)

    The third variable is the flim speed (ISO). A normal color film for general use is 100 ISO. A 'fast' film for lower-light photography is 400 ISO. A fine-grain film for detailed work would be 25 ISO.

    ISO values
    25
    50
    100
    200
    400
    800 - specialist value - usually 'pushed' by the lab during development
    (Each ISO value gives twice as much light as the previous one)

    In photography, once you've put a film in the camera, you only have to worry about aperture (f-stop) and shutter speed. For an average daylight shot you'd be using something like f11 at 1/250 (or thereabouts). If you wanted to shoot someone jumping in the air, you'd use a faster shutter speed, say 1/1000 at f5.6. Note that these 2 combinations let in the exact same amount of light.

    f11 @1/250 = f5.6 @ 1/1000

    Exposure value (Ev)
    This is a combination of all three factors - f-stop, shutter speed and ISO. It's just a convenient way of getting a general starting value.

    As far as Iray goes, I haven't had the time to check how closely these values correspond to real life, so I'm not even going to guess at it. I don't think there's much benefit in adhering strictly to conventional photographic values. In real life, there's no such thing as an f-stop of 7.5, but there's no reason why you couldn't use it in Iray. The real life numbers are only good as a guide. Knowing that f8 is twice as bright as f11 is at least a start.

    mac

  • hphoenixhphoenix Posts: 1,324
    edited December 1969

    I think that people are forgetting that Iray is an unbiased renderer.....therefore, it simulates light as accurately as possible. Therefore, the 'camera' analogy used in most rendering is also used. So some basic knowledge of photography and photometry is needed to properly light, frame, and 'photograph' the 3D scene.

    Blowing out the values on lights and emissive surfaces has lots of side effects. When you enable bloom, if you've done this, you'll get huge amounts of bloom (in size, if not in intensity). It also causes inappropriate light color spread on surfaces that are illuminated. Yes, it's still unbiased, and yes, you'd have to use INTENSELY powerful lights to compensate for the poor choices of film, shutter speed, and Fstop. The default settings for those are really poorly chosen, so it is understandable why unrealistically powerful lighting is being used.

    Also remember that unlike a biased render, an unenclosed area WILL lose light! If the light goes off to infinity it never bounces back into a surface. If the light can bounce 'out' of the scene, some will, and this will reduce the total light that can reach the camera. Also, unlike with most lighting in biased renderers, the light in Iray WILL fall off with the square of the distance. Might want to look up the difference between illuminance and radiance.....it is a critical concept in this regard.


    Use appropriate lighting values. Typical 60w incandescent bulb is about 700 lumens at around 2900K. Fluorescent tube of 40w is about 2400 lumens, at around 5000K. If your scene is too dim, adjust the tone mapping (camera/environment) settings! If you still can't get it quite right, it's okay to tweak those light intensities, but try not to get in the habit......And obviously, certain 'unreal' effects may require you to do all kinds of crazy things to get it to look right. For those, try to get the scene correctly lit and photographing properly, THEN add the effect and any wild settings to IT, not the rest of the scene.

    Flash photography involves much greater amounts of light, but for very brief periods (much like the shutter speed!) to overlight the subject, and the choice of film speed has to be adjusted to compensate, or the shutter speed changed.

    There is a whole science/art to properly lighting/photographing a scene. It isn't THAT complex, but you do have to learn a little about it to make good choices when it comes to scene composition. A few hours can teach you a lot about how Fstop, Shutter speed, and ISO/ASA film speed effect each other and the final photo. It's worth a few hours to learn it.

    But, with all that said, if it gets the image looking 'right' to you, then it's sufficient. :)

  • SnowSultanSnowSultan Posts: 2,288
    edited December 1969

    Typical 60w incandescent bulb is about 700 lumens at around 2900K. Fluorescent tube of 40w is about 2400 lumens, at around 5000K.

    That is exactly the sort of information I'd like to see more of. Real values to use and subsequently adjust tone mapping settings to suit.

  • KatherineKatherine Posts: 295
    edited December 1969

    Typical 60w incandescent bulb is about 700 lumens at around 2900K. Fluorescent tube of 40w is about 2400 lumens, at around 5000K.

    That is exactly the sort of information I'd like to see more of. Real values to use and subsequently adjust tone mapping settings to suit.

    There are a ton of charts and tables online. You can Google for those as well as temperatures for the lights....The lower the value, the "warmer" the light.

    Kat

  • hphoenixhphoenix Posts: 1,324
    edited December 1969

    There's lots of information at the various light manufacturers websites. But there is considerable variation in values and measurement methods.


    On a side note, I wonder how many people are now tempted to get one of these:
    nVidia Visual Computing Appliance (VCA)

    No idea of the cost, but I'm betting close to or over six digits in the price.....but it'd make Iray scream with pleasure.....
    :cheese:

  • Herald of FireHerald of Fire Posts: 3,489
    edited December 1969

    I think I'm finally getting to grips with the emission settings. Thanks to all those who responded with useful tips. Redid an earlier scene with some changes and it was incredibly dramatic (like a million flashbulbs all being fired off in your eyes at once!) soo... after toning it down significantly and getting it to an acceptable level, here's the result.

    Came out quite nicely I think. Aside from some minor modifications to the glass, and obviously the emitters, every surface is using the Daz Iray presets or was auto-converted.

    Future2.png
    1000 x 707 - 1M
  • Zev0Zev0 Posts: 5,650
    edited March 2015

    Zev0 said:
    Is there a way to reduce the Z-scale of the dome? when I reduce size to match scale to figure, the fisheyed lense effect is kind of strong.

    Click with right mouse button on the Render Setings tab and activate "Show hidden properties". You will than have dome widith, hight and depth sliders. Plus bunch of other hidden stuff.
    Switching to a Finite Dome makes those dome settings visible.

    Yes but the depth, width and height has to be unhidden. Once unhidden, when I dial them up, I see no change to the sphere. I get a serious fisheyed look when I reduce the hdri size (to match figure scale), so I was hoping adjusting the depth would counter that, but it does nothing from what I can see.

    Post edited by Zev0 on
  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    Just went and grabbed a couple of boxes of lightbulbs from the closet...

    GE Softwhite incandescent 75w 1170 lumens no temp given, but assume typical of 2700K to 3000K
    Great Value Compact Fluorescent 19W 1300 Lumens 2700K
    Great Value Compact Fluorescent 23W 1600 Lumens 2700k

    Most bulbs will list that info, somewhere on the package. So, take a notebook and write down the info next trip to the store.

    For unusual bulbs/specialty bulbs most websites that sell them have the info.

    Then there's all the charts that Kat_Briggs mentioned.

    A way to change the scene without much fuss...change the color temp of the lights. Going from 2700 K to 3500K (or 5000K...that would be from 'soft white' to 'cool white' or 'daylight') makes a very noticeable difference.

  • SnowSultanSnowSultan Posts: 2,288
    edited March 2015

    There are a ton of charts and tables online. You can Google for those as well as temperatures for the light

    Could you post a link to one, because I couldn't find any settings as clear as what hphoenix posted. I'm still trying to find out decent settings for candle light.

    Numbers like those are great for new users who may be completely new to realistic rendering.


    edit: cross posted

    Post edited by SnowSultan on
  • mjc1016mjc1016 Posts: 15,001
    edited December 1969

    Should 1 lumen and about 1900k for a candle...

    Here's one page with info/charts

    http://repairfaq.cis.upenn.edu/sam/icets/basicp.htm

    And a nice color temperature chart

    http://photographyguide99.blogspot.com/2012/10/the-color-temperature-of-light.html

  • OstadanOstadan Posts: 965
    edited December 1969

    hphoenix said:
    There's lots of information at the various light manufacturers websites. But there is considerable variation in values and measurement methods.


    On a side note, I wonder how many people are now tempted to get one of these:
    nVidia Visual Computing Appliance (VCA)

    No idea of the cost, but I'm betting close to or over six digits in the price.....but it'd make Iray scream with pleasure.....
    :cheese:

    $50K in that keynote address on YouTube. More than the car that is being modeled in the demo. The fantasy of buying one did cross my mind briefly. I lay down until I felt better.

  • starionwolfstarionwolf Posts: 3,228
    edited December 1969

    Kyoto Kid said:
    ...when I use Dome/Scene though the scene renders dark. when I switch to sun - sky it renders correctly.

    I have a similar issue. When I use Dome and Scene environment mode, my scene renders dark. I do have a photometric spotlight though. If I delete the spotlight and render the scene, the scene looks decent. I'm trying to use a null to light the outside of Dream home's living room while the spotlight lights the inside of the living room. Is there a way to increase the brightness of the sun/null object? Increasing the disc intensity or glow strength to 10 doesn't seem to do much. the Render using sun-sky mode looks worse. I must be missing something. Sorry, no screenshots. Maybe I can post some after dinner.

  • KatherineKatherine Posts: 295
    edited December 1969

    I think I'm finally getting to grips with the emission settings. Thanks to all those who responded with useful tips. Redid an earlier scene with some changes and it was incredibly dramatic (like a million flashbulbs all being fired off in your eyes at once!) soo... after toning it down significantly and getting it to an acceptable level, here's the result.

    Came out quite nicely I think. Aside from some minor modifications to the glass, and obviously the emitters, every surface is using the Daz Iray presets or was auto-converted.

    Very nice!!

    Kat

  • kyoto kidkyoto kid Posts: 31,156
    edited March 2015

    I actually really like this engine, I'd probably love it if I had better cards: I'm running n CPU mode on my i7, 12GB RAM and it's response time for me is slightly slower than LuxRender with me stating here and now I really don't think I know how to light a scene yet and light planning can speed up or cripple a scene. Here are some observations and suggestions


    observation:
    Replacing your card:
    Iray will not work on my card 1GB nvidia card and any new card I get would be working PCIe 2.0 on my mobo , that's half bandwidth of PCIe3.0, also some cards require more power and that's a new PSU to buy as well foe some. Theres a consensus here who feel just replacing the card will see dramatic improvements but that's only true with systems that have newer hardware and adequate power to those cards t begin with, otherwise it's not as simple as just replacing the card in some, possibly many cases.

    [...]


    ...interesting, I am getting much shorter render times in pure CPU mode with Iray than with Lux. After 1 hour of rendering I have little if any noise in Iray compared to what I see with Lux after 9 - 10 hours (using the same test scene at the same resolution).

    My system is somewhat similar, i7 930 @ 2.8 GHz, 12 GB memory (tri Channel mode), Nvidia Fermi GPU with 1GB GDDR5 (dedicated). Currently using several meshlights as well as the Iray Sun/Sky setting with slight amount of haze (2.00).

    Post edited by kyoto kid on
  • kyoto kidkyoto kid Posts: 31,156
    edited December 1969

    @SnowSultan and others in the 3 Pillars of Photography discussion!

    It's not that I disagree with changing those settings, it's that I knew jack about those specific things before this discussion! I've never been able to afford a DSLR and always used digital cameras that had "for dummies" settings for my texturing (or a scanner).

    I had to go look up the 3 Pillars yesterday just to understand what ISO was. In my last render I posted to the "show us Your Iray Renders" thread I did play with the aperture and ISO and improved the strength of my lights considerably (that scene was lit with two weak photometrics and a small amount of environment light).

    Definitely one cannot use the default render settings for both ISO AND photometric light strength, though. Leaving default ISO the photometrics require very high lumen values, or leaving default photometric strength values (1500 lm??) the ISO must be changed.


    ...the physical functions of a DSLR and an old film SLR are the same (I have some experience with the latter). Been experimenting with different ISO (film speed) F-Stop and exposure settings and am able to get from what looked like an old "Kodachrome 64" print (with the richer colours) to results similar when using high speed Ektacrhome 400.
  • kyoto kidkyoto kid Posts: 31,156
    edited March 2015

    hphoenix said:
    There's lots of information at the various light manufacturers websites. But there is considerable variation in values and measurement methods.


    On a side note, I wonder how many people are now tempted to get one of these:
    nVidia Visual Computing Appliance (VCA)

    No idea of the cost, but I'm betting close to or over six digits in the price.....but it'd make Iray scream with pleasure.....
    :cheese:


    ,..50,000$ last I remember.

    Hmmm....Megabucks Lotto draw tomorrow.

    Post edited by kyoto kid on
  • SzarkSzark Posts: 10,572
    edited March 2015

    Dumor3D said:
    Well... so far my attempts at emissive surfaces have all been a bust. If they're emitting any kind of light, it's impossible to see and even when they're in direct view of the camera, there's no ambient light to the surface itself. I suppose I could crank up the luminance to a few billion, but at that point 'physically accurate' rendering goes right out the window.

    I'm sure there's a trick to it that I'm missing, but I can't figure out what that could be. Any tips so we can finally lay this bag of snakes out straight?

    There are different setting for the emissive lights. By default, it is set to 'I think' candelas per meter squared. (not sure what cd stands for?). Correct, it is Candella.
    DAZ Studio works in CMs. Slosh pointed out to me yesterday that you can change this to cd/cm^2 which switches it to CMs. So, meters squared to centimeters squared is a factor of 100. There is also Watts. My personal favorite.

    Anyway, using the default of meters squared, depending on the size of my emitting mesh, I'm seeing where setting luminance into the 100,000s, millions or billions is not uncommon to get enough light out of it. Throw the 0's at it! :) It seems like some of the monies in the world are like this, too.

    Actually 1 cd/cm^2 would be 10,000cd/m^2, I think - 1 m =100 cm, 1 m^2 = 100*100 cm^2

    Correct. Note that another option is Kcd/m^2.

    Lumens, and Watts for large objects don't really make sense. as the power is spread over the entire object.

    Also remember the large numbers (cd/m^2 for example) are likely because the object is either far away or the tone mapper is set for outdoor daylight settings, when the scene is not outdoors during daylight. :) OK so one Candela equals one candle power which makes the info I found on many sites the same as the Wiki http://en.wikipedia.org/wiki/Candela. Below is an extract from that Wiki page, giving us an idea on how to equate things.

    A common candle emits light with roughly 1 cd luminous intensity. A 25 W compact fluorescent light bulb puts out around 1700 lumens; if that light is radiated equally in all directions, it will have an intensity of around 135 cd. Focused into a 20° beam, it will have an intensity of around 18 000 cd

    Post edited by Szark on
  • kaz42kaz42 Posts: 62
    edited December 1969

    A quick plug, rather than crossposting a whole new post - I just made a big set of Iray shaders out of Nobiax's infamous free texture packs (with express permission to redistribute them).

    http://www.daz3d.com/forums/discussion/53881/

    Here's the link to the Freebies post. Download, pick them apart, learn how to make your own, and help make these better for the whole community! :)

  • Gooffball z45Gooffball z45 Posts: 2
    edited December 1969

    Is there a way to set the camera Iray uses?. That is, outside of what is being used for the primary viewport.
    I can't see any setting in the Iray render settings panel that reference what camera it is using.
    (I'm guessing it's fixed to whatever is the viewport default.)

    Thanks!

  • SickleYieldSickleYield Posts: 7,324
    edited December 1969

    Is there a way to set the camera Iray uses?. That is, outside of what is being used for the primary viewport.
    I can't see any setting in the Iray render settings panel that reference what camera it is using.
    (I'm guessing it's fixed to whatever is the viewport default.)

    Thanks!

    It's going to render through the camera you're looking through when you hit render.

  • CypherFOXCypherFOX Posts: 3,329
    edited December 1969

    Greetings,

    It's going to render through the camera you're looking through when you hit render.
    I always wondered about this; if I'm using a side-by-side video, or a 4-viewport view, how do I know which one is going to render if I hit Cmd-R, or click the render button?

    -- Morgan

  • SickleYieldSickleYield Posts: 7,324
    edited March 2015

    Cypherfox said:
    Greetings,
    It's going to render through the camera you're looking through when you hit render.
    I always wondered about this; if I'm using a side-by-side video, or a 4-viewport view, how do I know which one is going to render if I hit Cmd-R, or click the render button?

    -- Morgan

    You still have to have your mouse active in one, and I'm pretty sure that's the one DS is going to choose. If your mouse is over in Scene Tab or somewhere it'll probably go with the last one you directly manipulated. I'm willing to be corrected if I'm wrong, though, we're getting on in the day and Mr. Brain is not working as optimally.

    Post edited by SickleYield on
  • Richard HaseltineRichard Haseltine Posts: 55,231
    edited December 1969

    One of the viewports in a split view will always be active and that's the one that will be used. It would be nice to have visual feedback but clicking in the one you want is a good safety procedure.

  • SpitSpit Posts: 2,307
    edited December 1969

    I know this is OT for this thread, but speaking of the mouse over the viewport how do I get rid of the flashing with the pointer tool. We had the option before but I can't find it in 4.8. Not in tools or prefs..where is it?

  • SnowSultanSnowSultan Posts: 2,288
    edited December 1969

    Does anyone have any tips for minimizing fireflies? I just did a bunch of tests and here's what I learned:


    - Rendered a fairly dark interior room, 5 EV with three light bulb-like emitters, 700 L, 2900K -

    Render 1: Stopped manually at 87% after 7.5 minutes, 1100 intinerations. Noticeable fireflies.

    Render 2: Finished at 100% after 28.5 minutes, 4423 itinerations. VERY slight decrease in fireflies.

    Render 3: Finished at 100% after 15 minutes, 2320 itinerations. Nominal Luminance (under Firefly Filter Enable) set to 5, Noise Filter set to On with default settings. Slightly less bright fireflies, but the exact same amount as Render 2.


    I was going to try raising Quality, but do you have any recommendations? Do you think raising it to 2 would have any noticeable effect? Any advice is appreciated.

  • SzarkSzark Posts: 10,572
    edited December 1969

    Spit said:
    I know this is OT for this thread, but speaking of the mouse over the viewport how do I get rid of the flashing with the pointer tool. We had the option before but I can't find it in 4.8. Not in tools or prefs..where is it?
    you have to select the Surface Selection tool which brings up the options in Tool Settings pane.
Sign In or Register to comment.