First time rendering a night scene: Paper Lanterns over Water

[evanmichalski]

My first post on CG architect so hello and sorry in advance if come off as a noob at this, as you will painfully see in my limited understanding of 3DS+Vray

 

Anyways first off: Here's the precedent I'm following:

http://imgur.com/r39fe

 

As the title says, I'm extremely green when it comes to night renderings so I've been having difficulties the past 2 days trying to get a good lighting setup of a paper lantern in water. The problem I'm experiencing is the radius of the sphere light I'm using is bleeding out too far into the water; and it's 10x worse when you add 50 lanterns to the scene which basically saturates all of the water turning it completely yellow (I tried it, and it's nothing similar to what's going on in the precedent picture). Even adding a closed cylinder to block off the light protruding from the bottom doesn't help.

 

 

I've tried messing with the sphere light, modifying the Targ. dist, radius, lowering the multiplier, disabling/enabling diffuse, specular, and reflections, and even excluded the water from the light source, and none of it has helped.

 

To give you fellas an idea of the materials I'm working with to better understand what's going in here is a list of the materials and settings I've got going on, and maybe it'll give you insight and suggestions for me. I'm currently using a 2 sided material for the paper lantern with no shell (I tried giving it some thickness but that didn't seem to help), an HDRI with stars to give it a moonlight setting, water with a thickness of 1" and nothing but a vray plane a few feet below it, and caustics are disabled. Hopefully after looking at my settings it'll more or less give you guys enough insight to what I'm working with:

 

 

I'm sure there's 50 things going on wrong that I haven't quite figured out, not to mention the 50 trillion questions I have further regarding using pflow to assign the lights with the lantern onto the particles, but that's for a later time. Right now I just need to focus on the light itself before I even proceed onto the next step. Anyways, look forward to your questions, comments, or any further suggestions you might have for me, gracias....

[Nicolai Bongard]

If there is no need to see anything beneath the water, then just make it simply reflective, not refractive. And/or you could try to make the texture selfilluminating on the lamps, but not actually spread light, so that all you see is basically the "glowing" texture reflected in the waves, no lights involved at all, except the hdri.

[evanmichalski]

If there is no need to see anything beneath the water, then just make it simply reflective, not refractive. And/or you could try to make the texture selfilluminating on the lamps, but not actually spread light, so that all you see is basically the "glowing" texture reflected in the waves, no lights involved at all, except the hdri.

 

Turning off the refraction helped a lot, but I would definitely like to keep it going further, so can you elaborate some more what you mean specifically about the self illuminating the lamps, I don't understand what you're talking about, sorry. Basically what I'm asking I guess, what is the correct way to increase the decay so the sphere light only extenuates to a foot or two outside the lantern, because I just want to minimize the reflection on the water at this point.

Edited August 17, 2013 by evanmichalski

[Nicolai Bongard]

Have a look here: http://help.chaosgroup.com/vray/help/200R1/material_params.htm , and look for self illumination. If you set that to a color, basically the texture will appear to be (obviously, as the name implies) illuminated with the color specified. You might want to put a texture in there though, for the slight "falloff" on the paper. Even though there are no lights in the scene, the texture will still glow. If there are some lights in your scene, and your object with that texture is in a shadow area, it will still appear to be glowing. So what you can do, is to make sure the GI is not enabled (the little checkbox next to where you pick the self illumination color/texture in the vray material), so that the texture does not send out lightbeams so to speak. Then you put your actual vray light inside your lamp model, and make sure it ignores the "paper" material/object, both shadow casting and illumination. What youve achieved then is make sure that the paper on the lamp appears to be illuminated (controlled by the self illumination option), and the actual lights only affects the other elements in your scene, namely the water and whatever parts of your lamps that are not made of paper. That way, you control how much the paperlamp appears to be glowing with the material, and with the vray lights you control (with the intensity multiplier) how far you want the light beams going into the water to reach. Also, unless you have a need to see the bottomn of your lake, you should make the water deeper so that the light does not hit the bottomn and the bounce further through the water. The decay of the vraylight is basically a falloff gradient thingy unless you are using IES lights (they are somewhat fancyer, usually looks better when they hit a wall in a interior scene). How far the gradient reaches before it "dies out" is dependent on how strong the light is. So if you would want the gradient to go really far, naturally the surfaces close to the center of the light might be really bright, as the light is really strong. However, if you try the method i described, you should have greater control over how much the paper should appear to be glowing, and how far the light going into the water should go before it fades out. Hopefully some of this made sense, if not just ask!

[evanmichalski]

Thanks for the in-depth response, it's definitely gonna take some time to soak in and analyze this information and eventually apply it, but I'll follow up if I have any problems or hiccups whatsoever. Which if I know the way my brain chemistry works, will probably be more than likely .

 

On another topic I'd like to tap into with you if you don't mind sir....

 

In addition with the struggling of the lights, I've also been investigating how arrange the lights in natural fashion, so naturally I turned to the particle flow elements and been using this script I discovered: http://www.orbaz.com/forum/viewtopic.php?t=631. The problem I'm having at the moment is getting the sphere light that I'm using to attach directly the particle and have it follow the particle at the same speed, they're not in sync for some reason. The problem starts when I'm assigning the sphere light to the script, and when I save it, the sphere automatically attaches itself to the first particle, however, it's being assigned directly below it and I can't figure out why. Additionally, when I begin to play the animation, there's an obvious lag between the particle element itself to the sphere light, almost as if there's some sort of delay variable that's forcing it to do so. At first I thought it was because of the wind forces, so I disabled those, but the same thing was occurring. If you look at the screenshot here, maybe you can see what's causing that forced delay over time:

 

 

Edit:So out of sheer frustration, I started over with a blank scene to rule out all the possible variables, and it's functioning properly now where the light and the object follows the particle element at the same speed. The only problem I'm having however is getting the box attach to the particle from its center, rather from the base, because if you look at this SS:

you'll see how the light is below the box, when I need to get it inside, so basically I gotta figure out is how to assign the box at the origin of the plane because that is where the light is being attached at the beginning. Obviously, grouping the light to the box is causing it to crash, or I'm just doing something wrong, maybe you can figure out why or at least replicate the crashing, but that is basically the jist of it at this point. If I figure it out between now and then I"ll let you know thanks ...

[evanmichalski]

Oh and one more thing to add, assuming I get everything to work, is there a way I can bake the particle flow (without using a script) so I can retain the object and the lights without them turning into meshes or something else? Or is there a way I can turn off the particle flow while keeping the finalized element?

[Nicolai Bongard]

If you are not supposed to animate the scene but only use it for a still picture, i would have basically skipped the whole particle thingy, just copy and paste instances of your lamps to the positions of the particles when they are where you think looks nice. But if you stick to the particle stuff, one thing you could try to do is move the pivot point of either the lamp object ( a bit up) or the lights (a bit down). The pivot is basically the "center" of an object, but it can be moved anywhere. Assuming the particle generator uses the pivot as the center points when it distributes, this should work. However, you might end up with some problems if your lamps are set to tilt/rotate to the sides i guess, but you wont know until you try! Your last post makes no sense to me.

[evanmichalski]

Golden, thanks...