(FLASHBACK) Lighting Challenge #5: Under The Boardwalk


Please enjoy reading through this thread as an archive, but it is closed to new posts. You can still download the old models and also post your entry in order to ask for feedback here

A new lighting challenge is in the works, In the meantime, let’s flashback to Lighting Challenge #5!

Hard to believe this challenge originally took place 6 years ago! Your goal is to light and render the scene as if you are under water. Make sure to check out the old thread as well as the gallery for inspiration and tips. For this challenge you will only have about 1 month to participate. The deadline is August 31st, 2012.


[li]If posting your own rendered images or video of this scene anywhere out of this thread, please credit Serguei Kalentchouk for the modeling.
[/li][li]Use any 3d software and techniques you would like.
[/li][li]Changes to the scene are allowed but not required.
[/li][li]Post your work in progress by replying to this thread so you can receive feedback
[/li][li]Feel free to share any extra information or breakdowns to show your techniques or lighting set-up.
[/li][li]Ask questions and give feedback
[/li][li]Enjoy yourself!

You can download the 3D scene files from the following, if you can provide a file format not in this list, please PM me:

Download OBJ file):UnderTheBoardwalk_OBJ.rar
Download Maya file: UnderTheBoardwalk_MA.rar
Download Max file:UnderTheBoardwalk_MAX.rar
Download Softimage file:UnderTheBoardwalk_XSI.rar
Download Lightwave file:UnderTheBoardwalk_LWO.rar


That’s great we have those scenes to try again. I’ve got one question:
" Really when you’re underwater and look up at the water surface, the surface is mostly reflective: You can only see-through to above the water in a tiny area called Snell’s Window."

So how we could achieve it? Also any more tips on creating believable water would be interesting. I will try to share my thoughts.


Uhm I’m curious to test new caustics in vray :wink:


Havent tried it myself to see if it does what is described there, but maybe turning on ‘reflect on backside’ in the vray material does this.

Ok, i did a google image search on “snell’s windows” and im pretty sure this is not what the reflect on backside option in the vraymaterial does.


I tried making it with a regular reflection curve, doesn’t look that convincing for now.


Hi there,

Nice to see this challenge!

mister3d, thanks for that link. I never really knew about this. I don’t know the first thing about vray but I tried this with cycles: a camera facing up inside a rectangle that is surrounded by a huge sphere. The rectangle was made transparent and was given an IOR of 1.33 and applied a sky texture to the sphere.

The result was the entire section of the top half of the sky sphere shrunk to a small circle. Would this work with Vray as well? Or is it too inefficient or something?



halfPintMike, I’m not really sure what you mean that it shrinked. Were you trying to make the Snell window effect?

I found a good tutorial for underwater scene.

I’m thinking which Vray features could be useful. I think Vray fog.


mister3d - the darkness on water surface in this image sort of have that effect I think


Maybe with the right facing ratio/fresnel we could get it to reflect our fake dark card under water.


Hi all,

I’m happy to give a try to this scene, underwater is kind difficult. I did my lighting before seen the link of mister3d.

Still a lot of work to do, here is my first test render (with color correction)


There are quite a few characteristics of being underwater that really help a render look great Here are a few of them.

Depth fog/volumetrics- Water is not an entirely clear substance. All bodies of water have sediment and microscopic life forms that create a fairly quick dropoff from light. http://ic2.pbase.com/g4/64/655664/2/60273117.ytsurgeon_chilenoNov02.jpg You could achieve this either through volumetrics within your 3d package, or use zdepth to manipulate your image in post.

Caustics- Depending on the time of day and shadows there could be caustics from the surface of the water. http://farm3.staticflickr.com/2081/4514888781_19cc8b03dd_b.jpg You could make this physically accurate with caustics and a correct water surface or you could project an image of a caustic pattern down into the scene.

Water surface - A fresnel reflectance is extremely important when it comes to the surface of the water. As mister3D mentioned, Snell’s window is the result of the refraction of the sky through the water http://en.wikipedia.org/wiki/Snell’s_window With a physically accurate model and material this should happen automatically through reflection/refraction equations. However, for this scene you may have to use some projections to create and control the effect yourself.


FeD: Good start! The water in your image is looking crystal clear. Obviously depending on how clear the water is there will be varying levels of “fog”. http://ic2.pbase.com/g4/64/655664/2/60273117.ytsurgeon_chilenoNov02.jpg You could either use some volumetrics or a zdepth pass which you can composite together. The surface of the water is too clear and could be reflecting the underwater area much more. Looking forward to some more updates!


Thank for the tips kanooshka, i’m gona try with true 3D volumetric and the render times are going crazing . The render in separated passes is the key I know, but a render out of the box would be so cool :).

If any one have tips for rendering faster fog in mental ray for maya, I will take


A while ago there was a wonderful plugin for rendering iso surfaces there’s the link to a video http://www.youtube.com/watch?v=wuCpWF8NdF0. Everything seems dead years ago. Does anyone know a substitute ??
Thanks in advance for reply


You could try creating a volume cube under create->Volume Primitives->Cube.Then scale it up to fill the water area.


Here is yesterday and some of todays experimentation.

2 lights both directional, one has a 2d ocean plugged into the light color like the visor fluid caustic example. The other light is driving the Parti-Volume shader(fog).

I am messing with particles for a suspended debris look.

One of my main hobbies is saltwater aquariums, so I talked (conned) a buddy into making me a few chunks of liverock to start some sort of shallow reef for the left 1/3rd side of the render.

One main problem of mine is getting “God rays” between the boards using a parti volume. If anyone has a tip or two on that I am all …eyes :shrug: .

Parti Volume

^ a good read for anyone struggling with murky water.


Reed5point0, great! It really shows the power of mental ray. Maybe add some more textures, and also try changing lighting direction, I think it could add to the feeling of 3d-dimensionality.



You could try creating a volume cube under create->Volume Primitives->Cube.Then scale it up to fill the water area.

Thanks for the tips, I’will take a look, I actualy used Parti_Volume to get “god rays”, but the render times are going mad.


One main problem of mine is getting “God rays” between the boards using a parti volume. If anyone has a tip or two on that I am all …eyes :shrug: .

Maybe some things to check :
-did you link one light to the parti_volume ?
-is the render camera in the box where the parti_volume is attached too ?
-is autovolume activated in MR ? (off in maya by default)
-does the light have shadow activated ?
Sorry if you already did everything, but some times it help to check again :slight_smile:

With the Mental-ray Parti_Volume Reed5point0 gave in link :(render times 8H)

the same render without the parti_volume box : (render times 1H)

And finaly the two composited together with color correction (maybe too mutch hehe) :


That’s some monstrous render time. But the final comp turned out pretty nice!


FeD I like final look, but – agree with Panupat, render times are too much.

Nice theme to explore, the underwater… I love it and I missed the original thread, so I’m in!
Trying to shade and light it with Renderman. Or mentalRay, I’m not sure yet))


FeD: The water surface is looking a lot better, and the fog is a great touch. The edge of the water in the background is too noticeable. With that area being so far away, I’d expect it to be much more uniform in color/value. I think you could use a zdepth pass underneath your partivolume pass. As for the parti-volume render times, increasing your Min Step Len, Max Step Len should help save render times. If it has some noise you may be able to remove it in post, saving render time. Some things I’d like to see is some more translucency in the grass, and some floating particulates if you can get around to it.

Reed5point0: Nice start! The caustics and depth fog are working very well. I feel the composition could be strengthened some, though I’m not sure if you’re at that point yet. Let me know if you’d like some ideas for some composition improvements. The particulates are flattening out the image a little. Having some out of focus particulates in the foreground could help bring some depth to the image. The pillar could use some more shaping, try moving its light a little more to the side so that it appears more round. Keep it up!