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Indirect light in closed room
Posted: 08 December 2012 09:06 AM   [ Ignore ]   [ # 31 ]
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Elele - 08 December 2012 06:23 AM

....Another option I was thinking of was using caustics and then adjusting the shaders. The only shader property that i know affects caustics, is reflection….


Transparencies, reflections, and refractions in your shader will also be affected by turning on caustics. Other shaders that also work with these shader channels like, Translucency and even SSS may be be affected as well.

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Posted: 08 December 2012 09:45 AM   [ Ignore ]   [ # 32 ]
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araneldon - 08 December 2012 03:05 AM
holly wetcircuit - 08 December 2012 01:22 AM

You don’t. You fake it.

I was not getting “defensive”. Carrara is *not* a physics simulator. It is an art tool.

I didn’t say it was a physics simulator. Some tools in Carrara attempt to mimic the real world… yeah, whatever.

So I’m like, hey, this hammer’s head is too narrow, it’d be easier to hit stuff if it were wider. And you’re like, nuh-uh, it makes a perfectly fine banging noise as it is. What can I say? raspberry (I’m so good at analogies <3)

As far as I’m concerned, there is no “art” in faking indirect light. Put another way, the work doesn’t become more valuable if I spend ten times as much time faking indirect light rather than letting a program do it for me. I’m sure there are people who disagree with me. They can suck it.

You’re getting snippy at one of the few people using Carrara to make a living. So maybe she knows what she’s talking about? I came from the theater, lighting and set designer. All we do in theater is fake it. Frequently and fervently. And when you do it often, it’s easy to fake it, it doesn’t take ten times more time, it takes a tenth the time.

The acrimony in these forums is really beginning to wear on me.

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Posted: 08 December 2012 11:15 AM   [ Ignore ]   [ # 33 ]
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araneldon - 08 December 2012 03:05 AM
holly wetcircuit - 08 December 2012 01:22 AM

You don’t. You fake it.

I was not getting “defensive”. Carrara is *not* a physics simulator. It is an art tool.

I didn’t say it was a physics simulator. Some tools in Carrara attempt to mimic the real world… yeah, whatever.

So I’m like, hey, this hammer’s head is too narrow, it’d be easier to hit stuff if it were wider. And you’re like, nuh-uh, it makes a perfectly fine banging noise as it is. What can I say? raspberry (I’m so good at analogies <3)

As far as I’m concerned, there is no “art” in faking indirect light. Put another way, the work doesn’t become more valuable if I spend ten times as much time faking indirect light rather than letting a program do it for me. I’m sure there are people who disagree with me. They can suck it.

What a bizarre hostile reaction. I didn’t say anything like that. I have no idea where you are coming up with that bs.

If you don’t want to learn what you are doing, I believe that *LuxRender may be for you: http://www.luxrender.net/en_GB/index (**edited because I named the wrong software…) it is the “physics based” renderer that the Reality plugin for D|S uses. As far as I understand there is no “art” involved at all. It does one thing only and it takes forever to do it…. No thinking or understanding of your tools necessary. smirk

In the meantime I don’t see how your posts are at all helpful. What have you suggested as a solution? Whether Carrara does it “wrong or right” We are offering SOLUTIONS. You on the otherhand are throwing a tantrum. Here, speaking of sucking, I think you lost this…

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Posted: 08 December 2012 11:39 AM   [ Ignore ]   [ # 34 ]
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evilproducer - 08 December 2012 09:00 AM

Just a thought here, but in a room lighting situation, generally you don’t use spot lights which are very focused and bright. You usually use a bulb with a translucent shade of some sort. What happens if you assume it’s a ceiling light, place a translucent light shade below it and then see what you get?


Just quoting myself as it was the last post on the previous page and may get overlooked in the coming crap-storm. wink


Just to reiterate though, how many people really light their rooms with spotlights?!?

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Posted: 08 December 2012 11:53 AM   [ Ignore ]   [ # 35 ]
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holly wetcircuit - 08 December 2012 11:15 AM
araneldon - 08 December 2012 03:05 AM
holly wetcircuit - 08 December 2012 01:22 AM

You don’t. You fake it.

I was not getting “defensive”. Carrara is *not* a physics simulator. It is an art tool.

I didn’t say it was a physics simulator. Some tools in Carrara attempt to mimic the real world… yeah, whatever.

So I’m like, hey, this hammer’s head is too narrow, it’d be easier to hit stuff if it were wider. And you’re like, nuh-uh, it makes a perfectly fine banging noise as it is. What can I say? raspberry (I’m so good at analogies <3)

As far as I’m concerned, there is no “art” in faking indirect light. Put another way, the work doesn’t become more valuable if I spend ten times as much time faking indirect light rather than letting a program do it for me. I’m sure there are people who disagree with me. They can suck it.

What a bizarre hostile reaction. I didn’t say anything like that. I have no idea where you are coming up with that bs.

If you don’t want to learn what you are doing, I believe that the Octane Renderer may be for you: http://render.otoy.com/ it is the “physics based” renderer that the Reality plugin for D|S uses. As far as I understand there is no “art” involved at all. It does one thing only and it takes forever to do it…. No thinking or understanding of your tools necessary. smirk

In the meantime I don’t see how your posts are at all helpful. What have you suggested as a solution? Whether Carrara does it “wrong or right” We are offering SOLUTIONS. You on the otherhand are throwing a tantrum. Here, speaking of sucking, I think you lost this…

I love ya, Holly, but just a correction. Reality uses the slow LuxRender and its faster GPU counterpart. Octane Render is only GPU and is very speedy if you set stuff up correctly and it does not work with Reality. It does work well with the Poser beta plugin and will soon with the DAZ Studio plugin and works very well with the 3ds Max and Maya plugins and also works without a plugin.

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Posted: 08 December 2012 11:53 AM   [ Ignore ]   [ # 36 ]
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Ahh sorry… LuxRender was the one I meant, I guess… I don’t use them obviously.

There is nothing about this situation that is “based in reality”. I also come from a theater/film background. “Natural-looking” bounce light takes a team of professionals and dozens of lights…. Any photographer or lighting designer will tell you that.

The time you save on rendering when you know what you are doing…., is worth a thousand tantrums when you don’t. Especially for the rest of us.

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Posted: 08 December 2012 12:34 PM   [ Ignore ]   [ # 37 ]
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Hi, as much as I enjoy reading a good argument (yes, even the acrimonious ones) I just want to bring this back a bit.

It seems I was wrong about the number of bounces affecting the indirect light, this is probably from me changing multiple things in tests that I did in the past. Bad science there.

Just from some simple experiments now I can tell that the range of the main light and distance falloff makes as big a difference as most things. The saturation of the shader then has an effect on the light colour and any shader at 100% is very unrealistic. The indirect light intensity then needs to be balanced against that in combination with the main light intensity. A wide spotlight behaves differently to a bulb.

A 100% sealed box with no way for the light to die would be physically impossible in real life but I think this is where the Carrara lighting model falls flat. You have to build a scene with that one fact in mind. Cutting a window in one wall makes the biggest difference.

I personally believe that indirect light should only be used to ‘fill in’ what the main lights can’t so really it should only be turned up until you can just about notice it. If it’s being used to provide the majority of light then that’s both physically and artistically odd. If I want to boost the IL or GI then I usually do it in post from the render layers, but mostly in post I’m looking to add more shadow and AO to help define shape and texture that’s been lost to overlighting. Indirect light in an outdoor scene is almost useless if it’s lit well to start with, you won’t even notice it. And I have no problem faking it with straight ambient light if I feel an image can use it.

In summary, balance the shaders, lights and indirect light against each other depending on the scene. Have fun trying new things.

P.S. I’m a physicist and I don’t believe any off the shelf physics model is even close to what would be called real world accurate, including the unbiased renders, every one is just an approximation that will function just well enough on todays technology. Bullet operates like an extremely grainy quantum universe using cricket balls and 1/24th second time slices instead of protons and an infinitesimal timescale.

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Posted: 08 December 2012 01:21 PM   [ Ignore ]   [ # 38 ]
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LIGHTING and SHADERS are everything in 3D…. There is a zen to getting what you want from them, and a lot of trial and error until you get the feel of the controls…. And it’s all a *system* so you can counteract one with the other…it takes a while. Really, this is not a science class. It is an art. With practice you gain skill. Yadda yadda ya (things you’ve heard 1000 times… Wax on… Wax off…) I’m sorry if that is not the answer you want, but that is the answer.

To add to Joe’s “tiny bumps”... What you have created in Carrara would be the photographer’s equivalent of a REFLECTOR, a large smooth surface designed specifically to bounce light. Sometimes they use posterboard so it is very smooth and white, sometimes you see a gold metalic one which is intended to warm up the subject…. And Carrara is doing EXACTLY what you told it to do: make a big colored-surface act as a tinted reflector when you hit it with a powerful spotlight… THAT IS WHAT WOULD HAPPEN IN REAL LIFE. Go try it.

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Posted: 08 December 2012 02:06 PM   [ Ignore ]   [ # 39 ]
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Ok, thanks for the replies. I’ll try some more smile

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Posted: 08 December 2012 03:16 PM   [ Ignore ]   [ # 40 ]
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Here is an example of why I don’t use GI much….

The top image uses GI to “fill in” the lighting. This is pretty much the default setting (100% Indirect Lighting, Interpolation = 20%, 5000 photon count…) If you click the image you can see “ashiness” in the lighting so this initially has a *wow* look of GI, but on closer inspection this is not acceptable…. I could turn off Interpolation and step up the photon count, but this image already took almost 2 hours to render….

Now look at the bottom image. This is where I “faked” GI. The scene uses 6 Ring Lights at the top of the columns. All I did for the “fake” GI is duplicate the lights in the scene, cut their brightness in half, and drop them down to the floor at the base of the columns…. Now there are twice as many lights in the scene, but it renders in 2min 45sec. Go ahead and look at the image large. It has no ashiness, but the lighting is very close… nearly identical… But with a few minutes extra work with the lighting in my scene, I have saved 1hr 57min of rendertime….

GI is actually the “fake” method to get good lighting. As you can see it comes at a ridiculous cost in rendertime.

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Posted: 08 December 2012 03:25 PM   [ Ignore ]   [ # 41 ]
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evilproducer - 08 December 2012 11:39 AM
evilproducer - 08 December 2012 09:00 AM

Just a thought here, but in a room lighting situation, generally you don’t use spot lights which are very focused and bright. You usually use a bulb with a translucent shade of some sort. What happens if you assume it’s a ceiling light, place a translucent light shade below it and then see what you get?


Just quoting myself as it was the last post on the previous page and may get overlooked in the coming crap-storm. wink


Just to reiterate though, how many people really light their rooms with spotlights?!?

Apparently you think that was such an important point that you need to re-iterate it, so I’ll address it.

I could give you a long list of lights used in room lighting situations that act like spotlights. In fact in my living room I use what are called “track lights”, which are a row of small, narrow beam spots mounted in a metal track you can move and adjust. They are used for accent lighting, and in my case that’s all that lights the room.

Also, most lighting fixtures and lamps are set up to focus a bulb so that it acts pretty much like a spotlight. You even gave an example, where a shade is used to focus the light. Because in fact a bare bulb in the room hurts your eyes, so nobody uses it. So really the vast majority of lights used in a room situation are some form of directed light, not a bulb.

Just take a look at the IES profiles of many of the lights provided by manufacturers and you’ll see that in fact there are many, many lights with spot-type profiles, either because of the bulbs themselves or the reflectors they are mounted in.

However I’m not sure what that all has to do with what we’re discussing….

Are you saying that if you use a spotlight in your simulation, which you’re not used to seeing lighting a room in real life, then your results might look weird because you’re not used to seeing it in real life? I dunno, but I don’t think that’s the issue the OP is having. I think it’s more about expectations.

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Posted: 08 December 2012 03:35 PM   [ Ignore ]   [ # 42 ]
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A little more refining: For my “bounce” lights I have reduced their saturation to about half, and I’ve changed the Shadow Intensity to 60%. I’m pretty happy with this lighting. It’s not *exactly* like the GI, but now my scene is rendering so fast that I have the luxury of tweaking the settings and re-rendering until I get it right…. If I wanted, I could keep adding more very low brightness fill lights, but I don’t think it’s necessary to get a convincing image. I also have the advantage that I can change the saturation of the “bounce” lights which helps to bring out the architecture a little more.

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Posted: 08 December 2012 03:38 PM   [ Ignore ]   [ # 43 ]
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RoguePilot - 08 December 2012 12:34 PM

A 100% sealed box with no way for the light to die would be physically impossible in real life but I think this is where the Carrara lighting model falls flat. You have to build a scene with that one fact in mind. Cutting a window in one wall makes the biggest difference..

Physicist or not, dude, I have no clue what you’re talking about. Are you saying that in Carrara the light in a radiosity sim never dies, especially if you’re in a closed box?

Of course that’s not true, because if it was the OP’s image would never stop rendering.

And to say that a sealed box with no way for light to escape is physically impossible is, well, rubbish. Go into a windowless room, close the door, and turn on the light. It’s called a bathroom. 

Apparently folks here feel that the radiosity sim in Carrara allows light to keep bouncing and re-enforcing the color far to much. Maybe you’re right, maybe that instead of 10 bounces it simulates 23 bounces. Who knows? But again, before you decide it’s too much, do a little research and figure out how to simulate your lights and materials so they correspond to real life and maybe your results will be closer to what you want to see. 

 

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Posted: 08 December 2012 03:59 PM   [ Ignore ]   [ # 44 ]
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JoeMamma2000 - 08 December 2012 03:38 PM
RoguePilot - 08 December 2012 12:34 PM

A 100% sealed box with no way for the light to die would be physically impossible in real life but I think this is where the Carrara lighting model falls flat. You have to build a scene with that one fact in mind. Cutting a window in one wall makes the biggest difference..

Physicist or not, dude, I have no clue what you’re talking about. Are you saying that in Carrara the light in a radiosity sim never dies, especially if you’re in a closed box?

Of course that’s not true, because if it was the OP’s image would never stop rendering.

And to say that a sealed box with no way for light to escape is physically impossible is, well, rubbish. Go into a windowless room, close the door, and turn on the light. It’s called a bathroom. 

Apparently folks here feel that the radiosity sim in Carrara allows light to keep bouncing and re-enforcing the color far to much. Maybe you’re right, maybe that instead of 10 bounces it simulates 23 bounces. Who knows? But again, before you decide it’s too much, do a little research and figure out how to simulate your lights and materials so they correspond to real life and maybe your results will be closer to what you want to see. 

 

Ok, that reads as angry, I thought I was agreeing with you and was merely posting some observations. Funny.

To answer one of your questions, in a 100% sealed room with a constant light source the photons would continually accumulate until it was filled entirely with light. This is clearly an impossibilty and actually impossible to observe.

What happens in reality is that for every impact of each photon an a surface a significant amount of energy is lost and converted into heat, this heat is then conducted out or radiated as Infra red, any reflected visible light has less and less energy for each bounce until it is no longer visible.

The act of having an observer in the room would add another ‘light sink’ because the only way to observe light is to absorb it. (A camera would see pure white or colour, a human would be blinded).

I think I’ve just described how a microwave oven works and how to cook a cat.

Carrara does not simulate this energy loss and the number of light bounces becomes irrelevent (It maxes at the max setting anyway). This is not a complaint, merely an observation that will help in understanding and lighting a scene correctly as well as indicating that upping the ray depth can be useless in some cases.

Astrophysicist by the way.

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Posted: 08 December 2012 04:13 PM   [ Ignore ]   [ # 45 ]
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JoeMamma2000 - 08 December 2012 03:38 PM
RoguePilot - 08 December 2012 12:34 PM

A 100% sealed box with no way for the light to die would be physically impossible in real life but I think this is where the Carrara lighting model falls flat. You have to build a scene with that one fact in mind. Cutting a window in one wall makes the biggest difference..

Physicist or not, dude, I have no clue what you’re talking about. Are you saying that in Carrara the light in a radiosity sim never dies, especially if you’re in a closed box?

...

And to say that a sealed box with no way for light to escape is physically impossible is, well, rubbish. Go into a windowless room, close the door, and turn on the light. It’s called a bathroom….

I *think* what Rogue was saying, is that in 3D we can build situations where all light emits from an infinitely small point, and bounces off a perfectly flat plane… without any of the “roughness” or atmosphere to absorb or scatter light…. In 3D we can create situations that are so “simple” as to be ad infinitum, that they do not look like anything in the real world…. We actually have to choose options to mimic the normal scattering, falloff, absorption, and bounce of light.

Carrara’s GI is also totally off kilter if you are using a shader domain to emit light via the Glow Channel, as opposed to an entire object emitting light with Glow…. Why? I don’t know (some calculation of surface area?).... Not all of Carrara works like the real world or how I think it “should”.... There is also a plugin called Shaders Plus at digitalcarversguild.com that adds some GI controls to shaders to help.

RoguePilot - 08 December 2012 03:59 PM

Astrophysicist by the way.

raspberry

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