Reef WIP

[cyphyr]

Plenty still to do on this
I know the lighting is more than just a bit off! It's about ten times too clear!
I want to make the canyon to  the right darker and the foreground shadowed area more illuminated.
When I get something I'm happy with, layout and lighting wise, I want to try using the depth pass to fade our the different colour channels separately. It should work but it will require somehead scratching to figure out
Cheers
Richard

[gregtee]

You're off to good start but honestly I'd lose the building unless you're willing to build in a lot of coral buildup detail to the model outside of Terragen that you'll have trouble getting inside it.  I've also learned from experience that these types of deeper water underwater scenes tend to look better when the light comes from above unless you're dealing with very shallow water environments, then raking the angle like a traditional landscape can work. 

Having said all that I like that more here are starting to do this kind of stuff.  It's something that I've been giving a lot of thought to lately in TG and I'm sure we could all learn stuff from each other.

-Greg

[Dune]

Yes, more light from above would make it better I think. Maybe you should put the building further to the back, more vague. And maybe you can use the ivy generator to grow 'something green' all over it. I agree it's too clean. But I like the explosion of light. You probably didn't even need a water shader here 

[fleetwood]

Definitely nice start, draws you in.
Wonder what it would look like with the main light shadows turned off and a real weak light casting the shadows, or maybe ridiculously wide soft shadows.

[cyphyr]

Ok, you absolutely right about the temple model. Mother said it reminded her of a goldfish bowl! It has to go, but can stay as a useful object to do some more tests with ... for now.

Looking at the Google image searchimages of coral reefs I've become convinced many of the really bright ones are done with flash photography but nonetheless you can see the light fall off very convincingly.
The only way to do this in Terragen will be to use the render elements and use a grey scale depth pass to fade out the saturation of the coral as it recedes into the distance. Below is a first attempt at this. It works (technically) but needs plenty more effort. Following on from this I will need to find out a way of doing the same de-saturation but on a per channel basis.
Cheers
Richard

[fleetwood]

You could use a Distance Shader input into a Adjust Saturation Colour function and it will fade the saturation as distance increases.
You could set the Distance Shader to use either the Z-depth or Spherical distance.

[cyphyr]

That will work for planet surfaces (thankyou, this may be useful) but not for population surfaces. That will have to be done with modified depth passes.
Richard

[gregtee]

You are exactly correct there Richard with regards to the falloff technique.  That's how I've always done underwater stuff.  Renders are always done full RGB and then later in comp we attenuate the ref and green out according to distance from camera and add the fogging effects  There's a lot of variables involved on how much attenuation you get but red always attenuates first, followed by green.  It looks like you're off to a great start here. 

I was messing with this last night and finally got frustrated as I couldn't get the Snell's Window effect to work correctly no matter what I tried though I've seen it done on Dune's renders so I know it's possible. 

-Greg

[gregtee]

Here's a really good example of red attenuation, followed by green, which then gives way to full blue only.  From this example, red is gone about 4-5 meters away from camera as the image clearly shifts to green/blue.  About another 7-8 meters away the green gives way to solid blue, which eventually forms the backdrop color.   

I use Nuke to process the depth mattes to do this but you can use anything these days.

Another example is the Snell's Window effect looking straight up past the divers which is what's presently kicking my ass. 

[cyphyr]

Slight update.
Not processing the channels separately yet ... Used the depth pass to add some blur and a slight kick back on the levels.
Depth pass is so very useful
Richard

[kaedorg]

As a retired Padi diving instructor and a professional underwater photographer i bring you here some informations about colours and luminosity underwater.

                         Absorption

Light intensity                    Depth in meters                     Disappearance of colours
           40%                                1 m                                            infrared
                                                   5 m                                            red
            14%                               10 to 15 m                                oranged
            7%                                 15 to 25 m                                Yellow
            1.5%                               25 to 60 m                                Purple / then Blue/Green
            1%                                  About 70 m                               monochrome (end of colours)

Another point is that with a mask : things seem closer by 3/4 of the distance.
Ex : a Fish at 1 m from you will seem to be at 0.75 m

And things also seem bigger by 4/3 of the size
Ex : A Fish 1m long will seem to be 1.33 m long

David
           

[gregtee]

Awesome stats!  Now if we can get the Planetside team to make an underwater "atmosphere" that mimics these values. 

[Dune]

This is really cutting wood, guys! I'm a bit frustrated I don't have time to dive into it again as well  I'll tell you that the Snell's window effect in my render was a (TG) trick, I don't think it can be done by just the water, etc.

Regarding the color falloff; using a (de)saturation node should be possible to be used on models as well, theoretically. Maybe I'll experiment a little with that.

EDIT: works.

[DannyG]

Nice Richard! I like the colors and camera placement

[cyphyr]

Meh! Forgot the depth pass!
Re-rendering with alterations ...