Using other light sources in IRAY

SO I've been playing around with IRAY a bit and I keep stumbling over how to actually use light sources.  Using IRAY's Sun-Sky only (with infinite sphere and dome off) enviroment option gives a nice naturaly lit outdoors look. But if I want to render indoors I'd expect to use the 'Scene only' option and then set up my own lights like I did in 3Delight.  Except instead of the kinds of light results I'd get in 3Delight, I get harsh white (or other base color) blasted across my scene.

And in Sun-Sky mode the lights I put in the scene don't seem to illuminate anything at all.

What is the deal?

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Comments

  • SickleYieldSickleYield Posts: 7,578

    Turn off your camera's headlamp in Parameters.  It's probably whiting out your scene lights.

    Subsequent to that, remember that if you're using photometrics it takes a big, big number of lumens to light a scene - sometimes you'll have to top out all the photometric spots at a million and use more than one if they're far from the character (they won't register numbers higher than that even if you set it higher, which makes me feel a bit stupid about  my earliest tutorial).  I find it easier to use primitives as mesh lights instead (apply the uber base shader and set emission to white) and light using kcd/m^2 as units, because it brings numbers within a manageable range of a few hundred units.

    And of course always remember that in a physically based engine, lights get weaker as you move them back away from your subject, and you have to turn them up.

    If you use mesh lights and the scene goes black in preview, hit ctrl l.  We don't have a way to preview mesh lights in scene yet.

  • fastbike1fastbike1 Posts: 4,068
    edited July 2015

    Here is an example that shows 3 photometric point sources at 1 million lumens. Point sources are perhaps 2 meters from the subject.

    Post edited by fastbike1 on
  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    I never use more then 20k lumens on a indoor ligth. if you need millions of lumens then your camera settings are wrong.

    Iray is VERY accurate... 10k lumens = is a very strong main photo ligth in a studio.

    a normal 100 watt bulb has (depending on the technology and reflector) 600 - 2k lumens.  a normal living room size needs maybe 3 - 5 such ligths and everything is bright.

    Using those values one cant go wrong - just tweak the camera settings until the image exposure is ok.

    A normal bed room usally has a 100watt bulb on the roof - a POINTLIGTH. this is a good start... camera 200 - 400 iso...  shutterspeed 120.. f stop 4- 5....   then add aditional litghs (spots and so on to set accents).

    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    This is a image using the values from above.

    1 Single 1500 lumens pointligth in a closed 10x10x10 meter cube. This is also what i expect from a 100watt bulb in such a hall :-) But everything is allready to see.

    I could now tweak the camera - Fstop to 2... the image is 2 times brigther.. or shutterspeed to 60 instead 120 the image is twice as brigth. Or add ligths.



     

    1500lumens.png
    1280 x 720 - 1M
    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    And here the correction on the camera..

    iso 400
    Fstop 2
    shutter 60

    Now we can see the whole 10x10 meter room allready very good. With one single 1500 lumens pointlight (one 100 watt bulb). In a real photosession i would now add lights ...  Because shutterspeed 60 is slow - but because we dont must be afraid of movements from Victoria (motion blur) we can do so here smiley.


     

    1500lumens correction.png
    1280 x 720 - 2M
    Post edited by AndyGrimm on
  • mjc1016mjc1016 Posts: 15,001

    Andy, that breakdown is probably the best summary of how to do a simple 'real' interior light setup;.

    One thing I would do, though, is use lights that could take IES profiles and attach a profile that fits the type of light I want.

  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    Thx mjc - Yes .. IES profiles is then the next step.. if we want accurate lighth we can load IES profiles in IRAY. This are spezification files, available for i think every manufactures lights, bulbs, fluorescents, LED ...

    They inlcude all the values such as beam angle, color temp,fall off, scattered light and so on.

    If somebody has a collection of the most common lights allready - welcome to post here.. Otherwise i will see if i can put some files together tomorrow.

    Post edited by AndyGrimm on
  • mjc1016mjc1016 Posts: 15,001

    Here's a set that I've used for a while in Luxrender...

    http://www.derekjenson.com/3d-blog/ies-light-profiles

  • jpb06tjpb06t Posts: 272

    Where can I find references to the camera equivalents of a human eye? e.g., when I am inside a well lit room my eyes behave like a camera with what ISO/f-stops?

  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    Our eyes change sensibility depending on the light and time (pupil goes large in a dark room, we see better after 10 minutes in darkness) - that's why there is no direct reference possible... but there is experience...  the values i posted above is a good start as you can see in the first picture.. in a 10 meter hall.. a 100 watt bulb IS very dark but one can still see the whole room with human eyes. And so does a professional fullframe camera (with high dynamic sensitivity) with 200 iso, Fstop 4 - 5 and shutter 120... While a cheap camera with the same settings would show just black outside of the light beam.

    brightness depends also a lot on the rooms wall and floor materials (reflection). Which is another reason why there is not a 100% reference setting possible. As we shoot on film we always did a quick exposure series (bracketing) because of this.





     

    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910

    Great set Mjc1016 - thx...  that's something to play around tomorrow smiley





     

  • mjc1016mjc1016 Posts: 15,001

    Here's some more to play around with, quite a few 'bare bulb', mostly LED, some CFLs (didn't see any incandescent bulbs there) from a variety of manufacturers...http://www.olino.org/advice/us/overview/results?fitting=E27&lamptype=bulb_all_around

  • AndyGrimmAndyGrimm Posts: 910

    yes - good link - which just reminded me that i always talked about a 100watt bulb = 1500 lumens...

    Today this is a 15 - 20 watt LED smiley

  • mjc1016mjc1016 Posts: 15,001

    Maybe I should put together an IES thread like I did for HDRIs...except that one could be very large.

    The one problem with IES files...there are too many of them floating around,  The major lighting manufacturers literally have thousands to choose from.

  • GuyBcapsGuyBcaps Posts: 32

    Thanks guys, this has been educational.

    Here's what I think I've figured out?

    Don't use distant lights (they seem to be what was causing my blinding white problem), use point lights with mid-to-high lumen values.

    Use F-Stop for brighter exposures.

  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    DSLR ...

    F-stop
    Shutter
    ISO

    all 3 paramaters result in a brighter or darker final image...

    And i think this is confusing for those which never shoot manual.

    F-Stop:  a smaller number means the aperture is wider open = more lighh. We must not take care DOF because this is a separate setting for your view camera (in your scene). This means we can use a F.Stop 2 without loosing sharpness (render settings).... 

    Shutter: A longer shutter time = more light....    we shoot stills (our objects dont move in iray) so we must not take care motion blur ....   this changes maybe in a future update when DAZ adds motion blur (Iray can do it)....  so it is reasonable to use real world values to understand what happens in a animation with motion blur (later).

    As a common rule do not use a shutter time larger then 1/60 with people (this is also the shutter speed for movie cameras taking 30 frames/second). While for stills (architectural interior images) it is common to use a tripod and very long shutter times to get all the light on the image which we need....  

    ISO: is simply a outdated number for the light sensibility of film... as higher the number so more bright your image will be. 

    Because todays DSLR can take pictures with very high ISO numbers.. such as 3200 or even 6400 without visible noise -> we have today a ALTERNATIVE setting to analog references...... that means we can use different parameter settings but with the same RESULT.

    if we ignore motion (blurring)

    ISO 100 with Shutter 50 is the same like ISO 50 with shutter 100.

    the same applies for F-stops (ignoring DOF...) but here we have "another number system)...

    F-stop 1.4, F/2, F/2.8, F/4, F/8 .....  F/1.4 is the widest open aperture in this chart. smaller values = more ligth.

    Each of those numbers = half(next higher number) or twice (next lower number) as much ligth.

    ISO 100 with aperture F/4 results in the same brigthness like ISO 50 with F/2.8 ​

    Post edited by AndyGrimm on
  • evilded777evilded777 Posts: 2,404

    Glad to see I am not the only one pushing correct use of the Tone Mapping tools to get a properly exposed image.

     

    Good Stuff AndyGrimm!

     

    And thanks for those links to IES profiles mjc... I really have to tackle that subject on of these days soon.

  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    @mjc1016    i searched for hours to find a simple 100 watt bulb which is acurate....   looks as it is now not just forbidden to sell them - even all the datas are secret now laugh.

    However i found it...   in the next posting i will apply a small collection using the ligths IES profiles which we growth up with. i think this is the best start for those which like to learn how to use correct ligths and camera settings... we all know how dark a 60watt incandescent osram bulb is smiley.

    until yet it contains:

    60 watt osram bulb
    100watt bulb

    Spots:
    par 36 50 watt - flood and narrow spot
    par 38 250 watt - flood and spot.

    Still trying to find some other ligths which we all know from the last 30 years cool


     

    Post edited by AndyGrimm on
  • jpb06tjpb06t Posts: 272

    Took out my Canon compact camera and checked the settings required to photograph the inside of my home. I discovered that to get a well exposed image without direct sunlight I had to crank the ISO up to 1600, open the diaphragm to 2.8 and even then I could not go below 1/30 s.

    From my past astronomy hobby I was well aware of how awesome is the adaptability of human sight but until today I had not measured it. Our homes seem well lit while in fact they are terribly dark. The conclusion is that if you put into your scene realistic lights you have to severely crank up exposure in order to get a scene which matches our perception.

  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    @latego yes your right...    i said somewhere above....  the big differences between cameras (the high end level and comsumer) is dynamic range....   the values which i posted for one low ligth 100watt bulb are for a professional fullframe camera with high end glass (lens) . a compact camera using the same settings wont see something - except the ligth beeam...

    pushing ISO up to 1600 or higher is the only way on a compact camera but the image will be very noisy. some mobiles have now a better iso noise ratio then compact cameras - strange but fact smiley

    and still even the best camera has a lower dynamic range then a healthy human eye but they come very close now.... 

     

    *The conclusion is that if you put into your scene realistic lights you have to severely crank up exposure in order to get a scene which matches our perception*



    Iray simulates a fullframe camera - so you cant take your values with your canon as reference....  But yes... even with a fullframe...  we expect BETTER results from a photo shoot then what we see with our own eyes -  because when the image has the same darkness as it is in reality - a lot of details are gone...Our eyes FOCUS on the detail in a dark room corner and adapt in miliseconds - move your focus away and there is just a grey dark blurry thing, We just  THINK we see the whole room bright- our brain tricks here...   that's why a photographer would add ligths to have a lower contrast (more details in the dark greys) in a large room. Because on the image IS the whole room not just the part you focus with your eyes,

    Post edited by AndyGrimm on
  • mjc1016mjc1016 Posts: 15,001
    edited July 2015
    AndyGrimm said:

    @mjc1016    i searched for hours to find a simple 100 watt bulb which is acurate....   looks as it is now not just forbidden to sell them - even all the datas are secret now laugh.

    However i found it...   in the next posting i will apply a small collection using the ligths IES profiles which we growth up with. i think this is the best start for those which like to learn how to use correct ligths and camera settings... we all know how dark a 60watt incandescent osram bulb is smiley.

    until yet it contains:

    60 watt osram bulb
    100watt bulb

    Spots:
    par 36 50 watt - flood and narrow spot
    par 38 250 watt - flood and spot.

    Still trying to find some other ligths which we all know from the last 30 years cool


     

    I was beginning to wonder if I'd have to break out an old, hard copy IES book and manually transcribe some of those profiles...

    Here's probably something that would be worth reading, even if it is positively ancient (1947).  The basics haven't have changed and there's a wealth of information.

    IES Lighting Handbook (It's the first edition and now almost 70 yrs later they are only on the Tenth edition...and that's probably more to do with the types of lights than the 'basics')

    Post edited by mjc1016 on
  • AndyGrimmAndyGrimm Posts: 910

    i just noted that daz iray does not use color temperature and lumens from a IES profle.. beam  fall-off and so on yes.... but color and luminance are overwritten by the two paramter fields above. 

    So we must know those two values for every profile (open in a editor and read first? ).. well strange.....

  • mjc1016mjc1016 Posts: 15,001
    AndyGrimm said:

    i just noted that daz iray does not use color temperature and lumens from a IES profle.. beam  fall-off and so on yes.... but color and luminance are overwritten by the two paramter fields above. 

    So we must know those two values for every profile (open in a editor and read first? ).. well strange.....

    I wonder if there is a way to override the override?

    Kind of makes it harder to use, having to pull out the values to plug them in, but it would only have to be done once...after a light is set up, save as a preset, but it would need to be done for each light made. 

  • AndyGrimmAndyGrimm Posts: 910

    ok - here is the scene for those which need help in setting up a "real" camera for interior images and correct ligths...

    NOTE that the settings are STARTING POINTS... how i would do it in a real session. the final image will be to dark but everything is to see...  correction files and IES profiles will follow

    BASE SCENE

    Camera: 30mm (this is a common start wide angel for interior - use values from 18mm - 50mm (closeups 85mm and portraits 85mm - 105mm) this values have to do with perspective distortions. I wont explain further just trust me here 
    Camera: Framewidht 36mm.... DO NOT CHANGE THAT .this is fullframe (again if you change it you change lense perspective distortion and focal length - the above values are not correct anymore!)

    Pointligth is in the middle of a 10x10meter room 1m above ground - DAZ standard values...  1500lumens 6500k - this is a very cold ligth - if you apply IES profiles everything will go yellow! we can correct the whitebalance in the render settings.. more to this later.

    Rendersettings:

    GENERAL: Aspect Ratio: 3:2 .... that's what a fullframe camera does.. leave it.. you can always crop later in photoshop if you want 16:9 as example.
    Pixelsize: that's up to you - jst keep the ratio if you want to see the real perspective of ligthbeams.

    TONEMAPPING: 
    Shutterspeed: 120 ( play around with values from 60 - 200 ) that's what i use when people are in a low ligth room 
    F/Stop 5 (variable use.. 2 - 8) i use 2.8 - 4 in low ligth ... i use prime lenses which go to 1.4 or 1.8.. but they have their sharpest spot somewhere around 2.8 - 4...
    ISO 200 (variable use 200 - 800)  i try to keep it as low as possible because of noise (which we dont have in Iray...  so use what you want ... 200 - 400 is what i would use in a real world scene, 800 if i can not do it otherwise smiley. 1600 if the bridge really must look like in sunligth on a beach while she is in reality in a dark low ligth church and i cant use flash cool...

    Attached is the fulll start scene.... images und ies profiles coming in some hours (need some sleep first)

     



    duf
    duf
    daz-iray-interior-ligth-camera.duf
    8K
  • AndyGrimmAndyGrimm Posts: 910

    and that's a screenshoot from the scene - showing the most important values if you work with your own room / ligth... 

    light-camera-interior.jpg
    1366 x 699 - 413K
  • GuyBcapsGuyBcaps Posts: 32
    AndyGrimm said:

     

    ok - here is the scene for those which need help in setting up a "real" camera for interior images and correct ligths...

    NOTE that the settings are STARTING POINTS... how i would do it in a real session. the final image will be to dark but everything is to see...  correction files and IES profiles will follow

    BASE SCENE

    Camera: 30mm (this is a common start wide angel for interior - use values from 18mm - 50mm (closeups 85mm and portraits 85mm - 105mm) this values have to do with perspective distortions. I wont explain further just trust me here 
    Camera: Framewidht 36mm.... DO NOT CHANGE THAT .this is fullframe (again if you change it you change lense perspective distortion and focal length - the above values are not correct anymore!)

    Pointligth is in the middle of a 10x10meter room 1m above ground - DAZ standard values...  1500lumens 6500k - this is a very cold ligth - if you apply IES profiles everything will go yellow! we can correct the whitebalance in the render settings.. more to this later.

    Rendersettings:

    GENERAL: Aspect Ratio: 3:2 .... that's what a fullframe camera does.. leave it.. you can always crop later in photoshop if you want 16:9 as example.
    Pixelsize: that's up to you - jst keep the ratio if you want to see the real perspective of ligthbeams.

    TONEMAPPING: 
    Shutterspeed: 120 ( play around with values from 60 - 200 ) that's what i use when people are in a low ligth room 
    F/Stop 5 (variable use.. 2 - 8) i use 2.8 - 4 in low ligth ... i use prime lenses which go to 1.4 or 1.8.. but they have their sharpest spot somewhere around 2.8 - 4...
    ISO 200 (variable use 200 - 800)  i try to keep it as low as possible because of noise (which we dont have in Iray...  so use what you want ... 200 - 400 is what i would use in a real world scene, 800 if i can not do it otherwise smiley. 1600 if the bridge really must look like in sunligth on a beach while she is in reality in a dark low ligth church and i cant use flash cool...

    Attached is the fulll start scene.... images und ies profiles coming in some hours (need some sleep first)

    This is the single most useful post I have encountered concerning how to use IRAY to its most basic effectiveness. THANK YOU

    Basicly I just had to forget EVERYING I learned about 3Delight.

  • SpottedKittySpottedKitty Posts: 7,232
    GuyBcaps said:
    Don't use distant lights (they seem to be what was causing my blinding white problem),

    You can use distant lights, just don't use anything like the default values —  if they're blinding white, turn them down. Way down; I usually start at a value of 5 or 10, run a quick test render to a few dozen iterations, and see if that needs to be bumped up or down a little bit.

    It's another of the things we're all going to have to learn about Iray lighting — distant lights in Iray will illuminate the whole scene at very, very low values.

  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    Distance ligths do NOT EXIST in reality. The only ligth emitter which come close to a Distance ligth is the sun and the moon...

    A distance ligth has parallel rays....  and is measured in cd/m2
    This means for us - dont use distance ligth in closed rooms - they never exist there.

    Do never use more then one in a scene (ether as sun or moon )...

    understand that your indoor camera values will be complete to sensitive and everything in light will be just clipped white.

    Full sun with highest luminance and reflective surfaces (white walls, snow and so on) we even use density filters on the lense (dark glass) to make everything darker and not over exposured.. that's exactly what happened to you...

    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910
    edited July 2015

    i just simulated it....

    I would have to set my camera to the lowest possible sensibility in 100% highest sunligth...  to take a picture of a large white cube... with reflection i would even need a density filter to see the different surfaces of the cube.....

    camera: iso 50
    Shutter 2000
    F-stop 22

    and i can start to see the cube normal - that's perfect strong sunligth on a cristal clear day - then when we can not sit on a white metal table without sunglasses. 

    I just googled: 10.000 lux = lm/m2 is the reflected luminance from sunligth wth 90degree on earth...  that's a really really stong lamp (the white reflective cube :-).

    Post edited by AndyGrimm on
  • AndyGrimmAndyGrimm Posts: 910

    Tonemapping

    Ok in the next screenshot are the corrected camera settings...

    Still we are in the same 10 meter room,,,   the ideal camera settings will show me as much as possible without clipping to white right under the lightball (1 meter above the floor).....

    The values i ended with are.

    Shutter 60
    F-Stop: 2.8
    ISO 800

    tonemapping.jpg
    1366 x 699 - 176K
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