Indirect light in closed room

124

Comments

  • wetcircuitwetcircuit Posts: 0
    edited December 2012

    ;-) It's all good! <3 Dont mention it ! :-P</p>

    Post edited by wetcircuit on
  • EleleElele Posts: 1,095
    edited December 1969

    Elele said:
    As far as I know the difference in intensity between the surfaces of the cubes comes from the angle they make with the light beam.
    The top of the cube has the largest angle (closest to 90°), hence the light is spread over a smaller area resuling in a brighter side, no?

    Yes, that's correct. But that's not what you were talking about, and not what I responded to....

    You said:

    "The top surface of the cube is the brightest, then the right and then the back.
    The light on one surface is pretty evenly distributed though and each surface is lit differently, hence creating the “harsh transitions” i was talking about."

    Now you're talking about "smooth gradients" on the surfaces?

    Like I said, you won't get smooth gradients on a surface unless the surface is not flat (y'know, like a sphere), or there is something else to cause the gradients.

    Honestly I have no clue what you're trying to get.

    Now, what I would do to Holly's model is this:

    1. Use soft shadows on all of my lights.
    2. Turn off any ambient light
    3. Don't use any radiosity or GI or anything like that.
    4. Decide where the greatest amount of bounce light would originate from in the scene, and stick wide angle spots there with the right color, soft shadows, falloff, and a low intensity (maybe 30% or something like that).
    5. Where my surfaces look uninteresting, I would spend a lot of time fixing the shaders to add interest. And I would also modify the mesh of the model as necessary to give the surfaces more interest (curve, etc.).

    Personally, I think that would give the image more interest and realism and impact. And all of that would be designed in line with the main theme and purpose I had for the image (suspense, horror, or whatever).

    Sorry, it was getting late and my english/art lingo is horrible at the best of times :D

    When you compare Holly's render's with GI and fake GI:
    The fake GI has those harsh transitions and even lighting I marked on the image.
    On the GI image, the lighting of those area's is a lot more varied (creating the "gradients").
    I don't know how to discribe this effect better. I just call it "GI" caus I haven't been able to fake that effect using other methods.

    To recap the reason for this topic:
    I had set up a basic scene with all shaders set to plain white to get a idea of how the shadows look. Everything looked fine in the GI render. I then gave the floor a basic wood shader and BAM, the whole room got filled with the color of the wood in the GI render.
    Normally when I do renders in open spaces, adding color doesn't cause this issue in the GI render. I've only encoutered this problem in closed off spaces.So I was wondering if other people had a solution for the GI in closed spaces. (If there are ways to fake the GI accurately then I'm interested too of course)
    I want to use a closed room because I might like to add some reflections later on. Reflections have a nasty habbit over revealing trickery that goes on outside the frame, like taking out the ceiling for example. I know there are ways to fake reflections too, but we'll keep that for another topic :D


    That method looks pretty handy, thanks. Do you have some example renders where you used it to fake GI (preferably in a complex scene)?
    I'm kinda wondering how long it takes to set up though. Usually my GI renders don't take too long, even on high quality settings. Sometimes the high quality renders still show errors though, so having an alternative would be usefull.

  • EleleElele Posts: 1,095
    edited December 1969

    So here's a test I did with making a lamp shade and using the same shader I used on my sphere in the previous set of images. The light settings are the same as well as the shader. Just the position is different and the geometry of the shade of course.


    The first image uses translucency in the shader, and just for Joe, I turned it off in the second one. Sorry, I didn't model any track lighting. ;-)
    Y'know, maybe somebody was right and my contribution to this discussion was irrelevant.

    I'll also post my shader to show how simple it is.

    That's a sweet lamp shader!
    And there is isn't as much color bleed from the floor... the plot thickens :D

  • EleleElele Posts: 1,095
    edited December 1969

    Elele said:

    As far as I know the difference in intensity between the surfaces of the cubes comes from the angle they make with the light beam.
    The top of the cube has the largest angle (closest to 90°), hence the light is spread over a smaller area resuling in a brighter side, no?

    Now how would you add lights to a complex model like the one Holly used, to fake IL and get smooth gradients? I think it would already be pretty difficult for a simple cube...

    Are you talking about falloff there rather than shadowing? We often visualise a cube as getting darker as it goes back and that's a sketch artists trick to simulate depth. Try setting the distance setting of your light to about room size (7ft?) and max the falloff to 100%. Better yet use an IES profile.

    Or do you mean that each side gets a different amount of light?

    On Hollys scene, curved surfaces are much easier to work with and give more subtle shading. Giving a cube a bevelled edge will help in a similar way.

    When I do interiors I match lights their real world positions and start working from there.

    This one is almost entirely lit by the bulbs in the lampshades, the falloff is just enough to ovelap each bulbs light sphere,
    http://fav.me/d56tyjm
    just a touch of ambient to lighten the shadows and ambient occlusion to darken them in the right place.
    (Never been 100% happy with that image, needs more debris)

    That it a funny image :D (In a good way)
    I'm still missing some of the "GI effects" though. For example the area where the shoes of the center guys touch the floor, to me it seems there is a lack of light interaction between the shoes and the floor wich gives the impression that the guys were "copy pasted" on the floor. Also the shadow of the flame shirt on the guys skin seems very dark, but maybe that can be fixed with Evil's translucency trick :)

  • EleleElele Posts: 1,095
    edited December 1969

    Here are some nice illustrations of IL that I would like to recreate

    Dining-Furniture-Placed-In-White-Wall-And-Wooden-Floor.jpg
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    depositphotos_4937440-Modern-red-and-black-bedroom.jpg
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    3230_REAL.jpg
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  • edited December 1969

    Heres the answer ... I say illuminate them all and let GOD sort then out!

  • EleleElele Posts: 1,095
    edited December 1969


    ...Shaders Plus at digitalcarversguild.com...

    Has anybody tried this or maybe some other plugins that affect GI?

  • evilproducerevilproducer Posts: 8,829
    edited December 1969

    Elele said:
    Here are some nice illustrations of IL that I would like to recreate


    The images you posted aren't closed rooms, and there is reflected color from the floors and ceilings onto the lighter colored surfaces. I would also point out that the light in those rooms is spilled in from out of doors which is full spectrum light and highly diffused as it's not direct sunlight. If you had direct sunlight shining in one of the those windows and hitting the floor you would see the reflected color much more dramatically.

  • EleleElele Posts: 1,095
    edited December 2012

    I had trouble finding closed room images, but they illustrate the IL nicely. Here are some other examples in closed rooms.
    I like the reflected color from the surfaces, that's exactly what i want. But I don't want the entire room to be colored, it is a subtle effect.

    CenturyFloorRedLR.jpg
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    64598575876408839_TIchZqvY_b.jpg
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    Post edited by Elele on
  • evilproducerevilproducer Posts: 8,829
    edited December 2012

    But they are colored, just not deeply saturated. They're also no spotlights. The image with the least reflected color bleed is the one with the fluorescent lights, which emit their tube shaped light through a large, rectangular, translucent piece of plastic. The hallway with the incandescent lights looks to be shallow recessed lights, which means it's a pretty wide aperture for the light go through and is not focused.


    Both examples have the light bouncing off the floor, but just as much bouncing off the white walls, diluting the effect of the reflected light from the floor.

    Post edited by evilproducer on
  • EleleElele Posts: 1,095
    edited December 2012

    But they are colored, just not deeply saturated. They're also no spotlights. The image with the least reflected color bleed is the one with the fluorescent lights, which emit their tube shaped light through a large, rectangular, translucent piece of plastic. The hallway with the incandescent lights looks to be shallow recessed lights, which means it's a pretty wide aperture for the light go through and is not focused.


    Both examples have the light bouncing off the floor, but just as much bouncing off the white walls, diluting the effect of the reflected light from the floor.

    Sorry, I'm having trouble understanding:
    "But they are colored, just not deeply saturated"
    Wich component are you talking about?

    "Both examples have the light bouncing off the floor, but just as much bouncing off the white walls, diluting the effect of the reflected light from the floor."
    That's how it is in my scene too, only the floor is colored and the walls and ceiling are white. But when i turn on GI the entire room gets heavely colored.

    I've been testing some more with the translucent shader and it is giving me great results :D
    I have no idea why, still testing, will post when i got more ...

    Post edited by Elele on
  • evilproducerevilproducer Posts: 8,829
    edited December 2012

    Elele said:
    But they are colored, just not deeply saturated. They're also no spotlights. The image with the least reflected color bleed is the one with the fluorescent lights, which emit their tube shaped light through a large, rectangular, translucent piece of plastic. The hallway with the incandescent lights looks to be shallow recessed lights, which means it's a pretty wide aperture for the light go through and is not focused.


    Both examples have the light bouncing off the floor, but just as much bouncing off the white walls, diluting the effect of the reflected light from the floor.

    Sorry, I'm having trouble understanding:
    "But they are colored, just not deeply saturated"
    Wich component are you talking about?

    "Both examples have the light bouncing off the floor, but just as much bouncing off the white walls, diluting the effect of the reflected light from the floor."
    That's how it is in my scene too, only the floor is colored and the walls and ceiling are white. But when i turn on GI the entire room gets heavely colored.

    I've been testing some more with the translucent shader and it is giving me great results :D
    I have no idea why, still testing, will post when i got more ...

    The hallway with the incandescent lights is more focused than the hallway with the flourescent lights, and so the white/off-white walls pick up more reflected light from the floor which adds to the color on the walls. There is still a wide spread of light from the bulbs as evidenced by the downward shadows the rails are casting on the wall, so it is clear the light from the incandescent lights are hitting the white walls as well, thus mitigating, but not eliminating the red reflected from the floor.


    Regarding your image, it is my belief that because you are using a spotlight which is a focused beam of directional light, it is hitting the colored floor, and only the colored floor before it bounces and hits the wall. In other words, the only reflected light (which is what IL simulates) is the color of the floor. It would be the same way in the real world. To get what you want, you need an omni-directional light source. Carrara has several of these available. The bulb is the most obvious, but there are shape lights and tube lights. The lamp shade suggestion that I had and tested is designed to eliminate the harshness of light.


    The other solution would be to aim the spotlight at a reflector to bounce the light. I'm trying that now. I'm bouncing the light off the white wall behind the camera in my scene. Common things to bounce light off of in the real world if you don't have photographic reflectors are walls, and ceilings, or poster board.

    Post edited by evilproducer on
  • EleleElele Posts: 1,095
    edited December 2012

    ok, now i get it :)

    I tried with light bulbs (as I mentioned before) and it is giving me the same results as the spotlights... and I've been testing with bulbs since then. Do you get other results when you use the bulb (without translucency)?

    Here are the renders i get for a lightbulb at 50% brightness
    -without GI
    -with GI set at 5% (very little)
    -edit: and one with a less saturated floor (255 128 128)

    Doc40.jpg
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    Doc33.jpg
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    Doc34.jpg
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    Post edited by Elele on
  • evilproducerevilproducer Posts: 8,829
    edited December 1969

    Elele said:
    ok, now i get it :)

    I tried with light bulbs (as I mentioned before) and it is giving me the same results as the spotlights... and I've been testing with bulbs since then. Do you get other results when you use the bulb (without translucency)?

    Here are the renders i get for a lightbulb at 50% brightness
    -without GI
    -with GI set at 5% (very little)
    -edit: and one with a less saturated floor (255 128 128)


    With that bright red floor, I wood expect to get that, yes.

  • evilproducerevilproducer Posts: 8,829
    edited December 1969

    Here's a couple I did with a spotlight bounced off the wall and the ceiling. I also did one with my lamp shade with a bright red shade. The first image is bounced off the wall, the second is bounced off the ceiling.


    The third image is the red floor. If you notice, the area around the light is more whit and the areas further away take on more of a red hue. I don't think this is inaccurate.

    red_floor.jpg
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    Spot_aiming_at_ceiling.jpg
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    Spot_aiming_at_wall.jpg
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  • wetcircuitwetcircuit Posts: 0
    edited December 1969

    I like your stucco shader... TUTORIAL TUTORIAL!!

  • evilproducerevilproducer Posts: 8,829
    edited December 1969

    I like your stucco shader... TUTORIAL TUTORIAL!!


    I hate to admit it, but it's one of the included shaders with the spot size scaled down a bit in the bump channel. :red:


    It's under Misc. and is called Semi-gloss Interior.

    Picture_1.png
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  • EleleElele Posts: 1,095
    edited December 1969

    I added a translucent spere around the bulb, changed the brightness to 100% and the GI to 100%, the rest is the same as before. This looks much better to me :D

    -without GI
    -with GI

    tr2.jpg
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    tr1.jpg
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  • evilproducerevilproducer Posts: 8,829
    edited December 1969

    Elele said:
    I added a translucent spere around the bulb, changed the brightness to 100% and the GI to 100%, the rest is the same as before. This looks much better to me :D

    -without GI
    -with GI


    I'm glad you're getting good results. I don't know what your plans are for the final image, but if you add more lights, you'll need to do what RoguePilot suggested in an earlier post and adjust down the light distance and adjust upward the falloff for your lights or it will wash out your image.

  • EleleElele Posts: 1,095
    edited December 1969

    Elele said:
    I added a translucent spere around the bulb, changed the brightness to 100% and the GI to 100%, the rest is the same as before. This looks much better to me :D

    -without GI
    -with GI


    I'm glad you're getting good results. I don't know what your plans are for the final image, but if you add more lights, you'll need to do what RoguePilot suggested in an earlier post and adjust down the light distance and adjust upward the falloff for your lights or it will wash out your image.

    Yes, this was just a quick test render. Thanks a lot :D

  • Kevin SandersonKevin Sanderson Posts: 1,237
    edited December 2012

    Elele said:
    I had trouble finding closed room images, but they illustrate the IL nicely. Here are some other examples in closed rooms.
    I like the reflected color from the surfaces, that's exactly what i want. But I don't want the entire room to be colored, it is a subtle effect.

    To get the subtle color effect you are trying for, you can do it faking GI with colored spotlights. Put them below your floor and above your ceiling. It may require a few. Experiment with your brightness setting and range falloff and other settings as well. You could color your spotlight under your red floor the same color and position it near your wall below the floor geometry. It was a technique Sub7th showed us in his fruit bowl tute.

    The first image has the spotlight enabled on all objects, the second image without the spotlight enabled

    without_spotlight.jpg
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    with_spotlight.jpg
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    Post edited by Kevin Sanderson on
  • Kevin SandersonKevin Sanderson Posts: 1,237
    edited December 1969

    And one with 80 percent range falloff. Looks pretty much like enough bounce light to me there.

    with80percent_rangefalloff.jpg
    1920 x 1080 - 191K
  • EleleElele Posts: 1,095
    edited December 1969

    The method using additional lights does seem handy, but I haven't used it much yet caus i don't have the skill to get good results. Also I usually render pretty simple scenes so the HQ GI renders rarely take more than an hour, so I'm wondering if in the end faking the GI is faster.

  • evilproducerevilproducer Posts: 8,829
    edited December 1969

    There's a bunch of sample interior scenes that come with Carrara. The easiest way to get to them is to use the scene wizard. There's scenes with caustics, GI and fake GI, so you can see how the scene was put together. It helped me quite a bit. I had forgotten about it until Kevin posted his examples which were made with the sample interior set.

  • Kevin SandersonKevin Sanderson Posts: 1,237
    edited December 1969

    Elele said:
    The method using additional lights does seem handy, but I haven't used it much yet caus i don't have the skill to get good results. Also I usually render pretty simple scenes so the HQ GI renders rarely take more than an hour, so I'm wondering if in the end faking the GI is faster.

    Depends on what you want to do. I'm no wiz at this stuff but it didn't take long to set it up at all. I would say you'd get your results much, much faster than with GI. Also, you can figure out pretty quickly if something is working or not because it renders so fast (if you don't have a ton of other things to slow it down).

  • Kevin SandersonKevin Sanderson Posts: 1,237
    edited December 1969

    There's a bunch of sample interior scenes that come with Carrara. The easiest way to get to them is to use the scene wizard. There's scenes with caustics, GI and fake GI, so you can see how the scene was put together. It helped me quite a bit. I had forgotten about it until Kevin posted his examples which were made with the sample interior set.

    Yep, I check some of those from time to time to get ideas.

  • JoeMamma2000JoeMamma2000 Posts: 2,615
    edited December 1969

    Elele said:
    Do you have some example renders where you used it to fake GI (preferably in a complex scene)?
    I'm kinda wondering how long it takes to set up though. Usually my GI renders don't take too long, even on high quality settings. Sometimes the high quality renders still show errors though, so having an alternative would be usefull.

    Yeah, I've got one I can show you using maybe 4 (or was it 5) lights to simulate GI. And I despise the term "fake GI" because it makes it sound like it's a poor substitute. It's not. If you understand light and materials you can do a nice job. Especially compared to those who don't understand light and materials and set up their scenes using poor modelling and just hit the GI button and expect wonders.

    Now, again, if you want to simulate what you see in real life, you need to model your scene as you see it in real life, and simulate light as it acts in real life. I contend that you could do an excellent job of reproducing those sample images you posted if you modelled the scenes to correspond to how those lights and materials really are.

    But to do that you have to understand stuff. For those who think it's some sort of "zen", and don't want to get cooties from that icky science stuff, then it's going to be a lot tougher and take a lot longer and may have poorer results. But IMO, you can't get around it: you've got to understand the basics if you want to do this stuff.

    LivingRoomLights.jpg
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  • JoeMamma2000JoeMamma2000 Posts: 2,615
    edited December 1969

    And for those who think it takes a long time to simulate GI, it doesn't. In fact, if you understand stuff, you can set up basic scenes with a few pre-set lights that you already know are gonna be needed. You KNOW for an outdoor scene you'll have a main sunlight, you know what its colors are, you know there will be a primary bounce light off the ground, and you KNOW there will be blue skylight coming from all sides.

    And for an indoor scene, you KNOW you'll have some primary light sources, and you KNOW that there will be floor and wall bounce lights.

    But you have to understand colors and diffuse and light properties and lots of icky science stuff. If you don't, then don't be surprised if your results don't match your reference photos.

    And in fact, I regularly recommend that a GREAT learning exercise is to take an actual photo and figure out how to model that scene to get a render that looks exactly the same as the photo. You should try it........

  • JoeMamma2000JoeMamma2000 Posts: 2,615
    edited December 1969

    And by the way, there is a huge downside to using GI or radiosity or whatever....

    It's called "artistic license". The ability an artist has to take reality and modify it to suit his purposes, to generate a mood in an image, to tell a story, to generate a certain emotion in his viewers. GI tries to reproduce reality. Artists generally want to take that one step further. They want to twist reality a bit to enhance a mood or an emotion. With GI, you basically set up your scene, and the GI simulator figures out how light would behave in that scene.

    But often you don't want that. Often you want to exaggerate the lighting, to generate, for example, a mood of mystery, or joy, or serenity.

    Now if you're a hobbyist whose only interest is to amaze himself that he could generate an image that looks all real and stuff, and have no interest in making images to tell a story or for others to enjoy, then yeah, do whatever is fun. But if you want to have flexibility and control over your images so you can tell your story, then GI might be less than ideal.

    And FWIW, this is not a new technique, or something that was discovered by anyone here. We were doing this back in the '80s and 90's before radiosity was even invented, and when GI solutions took weeks to render with the slow processors we had back then. And big studios are still doing it today to save render time and to have control and flexibility.

    It's a good thing....

  • JoeMamma2000JoeMamma2000 Posts: 2,615
    edited December 1969

    And here's one from long ago using 6 lights. One is the distant sunlight coming in the windows, and the rest are either direct lamp lights or bounce lights.

    Bedroom.jpg
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