Lighting a sewer

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Old 11 November 2012   #1
Lighting a sewer

I'm working on a project for a lighting class where I need to light a sewer,(actually the ninja turtle lair) and I want to achieve lighting without using any windows. I have a reference image for lighting that I'll link at the end of this post. I want the same lighting, but my bulbs wont be as bright. I was wondering if anyone had done something similar and could direct me on how to go about it, or point me towards a tutorial that would help. Thanks for any and all help!


reference:

http://renderbyhand.files.wordpress...sewer_final.png


Forgot to mention I'm in Maya using mental ray

Last edited by jibberishballr : 11 November 2012 at 04:42 PM.
 
Old 11 November 2012   #2
It really depends on which rendering engine you're using. With mental ray, I'd have LightSurface shaders for all the tube lighting, and likely a few cylindrical area lights too. In mental ray, you always want to try to use area lights when possible for best results; point lights, spot lights, etc. aren't great but sometimes they're necessary too.
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Old 11 November 2012   #3
Originally Posted by InfernalDarkness: It really depends on which rendering engine you're using. With mental ray, I'd have LightSurface shaders for all the tube lighting, and likely a few cylindrical area lights too. In mental ray, you always want to try to use area lights when possible for best results; point lights, spot lights, etc. aren't great but sometimes they're necessary too.


Can you explain what you mean by light surface shaders?
 
Old 11 November 2012   #4
Sure, in mental ray you can use the mia_light_surface shader in your Additional Color slot of the mia_mat_x material, which is the main material you'd want to use if you're rendering with mental ray.


What this shader does is emit "light" from an object's geometry. Final Gather light, and/or photon GI light, and it can also be linked to an actual scene light too. You would use this for a light bulb, for example, or a tube light such as a fluorescent tube. Or in a sci-fi scene, to make buttons or little LEDs glow.

Here's an example of such a shader on the glass geometry of these light-shades:



You can also control this shader with its own texture map, so it emits the light in patterns or varying intensities. Here's an example of that:



Hope this helps, or that your rendering engine (if not mental ray) has something similar that will help you.
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Old 11 November 2012   #5
That does help alot! Thanks! I'll mess around with it!

Last edited by jibberishballr : 11 November 2012 at 10:29 PM.
 
Old 11 November 2012   #6
I can't find any tutorials using this light shader...can you direct me to one?
 
Old 11 November 2012   #7
https://vimeo.com/19419930

https://vimeo.com/51985141
 
Old 11 November 2012   #8
Still having trouble figuring this out. I understand how to get the glow with the mia shaders, but still can't get the lighting i'm looking for. I think global illumination might help along with final gather but still a little foggy on how to use them. Also which light shaders to use is throwing me off. Right now I just have area lights (using raytrace, light shape of a cylinder (samples all at 1) and am messing around with GI and Final Gather. Any thoughts?
 
Old 11 November 2012   #9
Yes, you'll need to use Final Gather with the LightSurface shader. Photon GI is optional and requires "real" mental ray lights to work, of course. I whipped up some quick examples, not the best quality but hopefully they will illustrate how this shader works a bit.

A sample hallway, with a tube light only (mia_LightSurface only):


And here's one with the same Light Surface shader linked to spheres, which also contain spherical area lights:



And here's one with both the sphere lights and the tube light:

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Old 11 November 2012   #10
so you're using only the mia shader with FG and no additional lighting on those shots?
 
Old 11 November 2012   #11
Quote: which also contain spherical area lights:


The first image is just the Light Surface shader, attached to a tube (torus) at the top of my quick sewer shape. The second image is the same, identical Light Surface shader attached to some spheres, which contain within them spherical area lights as well (to emit photon GI and caustics). The Light Surface shader won't emit photons by itself, nor actual raytraced shadows. It's basically a Final Gather light casting shader, to sum it up.

That said, you can link lights to the Light Surface shader and control its intensity there as well, and thus changing the light's intensity will also change the Light Surface's intensity.

So yes, in that first render here there are no actual lights on in the scene, only the Light Surface is casting illumination:


The Light Surface shader is also very useful for "light cards" or reflectors, if you're going for, say, a studio look or more highlights in a scene.
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Old 11 November 2012   #12
gotcha I'll mess around with it for a bit. I really want to keep the scene dark, with only a couple lights, and as realistic lighting as a I can get. Any more tips are greatly appreciated
 
Old 11 November 2012   #13
Be careful using the Light surface shader on dimly lit scenes where the source is small. You may find that you will get a lot of final gather blotches and the only way to fix it is by increasing your settings to something that isn't production friendly and taking a unreasonable amount of time to render.
 
Old 11 November 2012   #14
Simpler is always better.
I don't know how much you need GI, FG on this.

Just throw in several lights with attenuation (5-7 meters) with soft shadows, and you're half job done. Put some fog, or volume light into the distance, for the atmosphere.
Also, few (no shadows) blue lights so you light a little bit too darken parts on your image. Something like ambient light.
After that, throw in Ambient Occlusion Pass (google that), so you can achieve global soft shadows.

Here's the similar scene, where I was in charge for a lighting, and did a similar setup, like described above:
http://i148.photobucket.com/albums/...ajac/hopa02.jpg

I think it's over-postprocessed (I would make that much darker, with less colors), but you get the idea.

Cheers
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Old 11 November 2012   #15
Originally Posted by d4rk3lf: Simpler is always better.
I don't know how much you need GI, FG on this.

Just throw in several lights with attenuation (5-7 meters) with soft shadows, and you're half job done. Put some fog, or volume light into the distance, for the atmosphere.
Also, few (no shadows) blue lights so you light a little bit too darken parts on your image. Something like ambient light.
After that, throw in Ambient Occlusion Pass (google that), so you can achieve global soft shadows.

Here's the similar scene, where I was in charge for a lighting, and did a similar setup, like described above:
http://i148.photobucket.com/albums/...ajac/hopa02.jpg

I think it's over-postprocessed (I would make that much darker, with less colors), but you get the idea.

Cheers


Wow! that looks great! good work! I tried putting in an AO pass but have difficulty getting it right (maintaining the low lighting). When you mentioned the lights (minus the ambient) what were you using (ie area, spotlight, etc)? If they were area lights were you using any shaders or specific settings?
 
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