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Underwater compositing - Sun rays and caustics

Posted by Marius Oberholster on Friday, February 6, 2015 Under: Quick Blog Tutorial
Hey all!

Now, recently, we've been talking about underwater compositing and today's example will show you just how much compositing it takes, at least in Blender, to really get that look.

Here is today's final:

As you can see, it looks nice and fuzzy, has a shallow water type feel to it, yet still quite deep as you can see the water surface and the beams stop before hitting the bottom.

This is what it looked like before any compositing was done:

Let's get on point for today's post - caustics and sun beams.

Caustics are a kind of light refraction that causes beautiful and concentrated light patterns from a transparent object (the refracts the light) onto a diffuse surface that can receive the newly scattered light. This is what you would usually find on the bottom of the pool on a bright sunny day, assuming the water is clear.

The sun beams, on the other hand, are caused by light shining into the water and bouncing off of the particles in the water. The dust in the water if you will.

Both of these effects, contrary to popular believe, can be achieved in Blender Render. GOD has given me a few and if you ask HIM, I'm sure HE'll reveal some ways to you too. One of which, I believe HE wants me to share right now; textured lights!
Didn't think it was possible right? Well, all you need to do is isolate to a layer that you want caustics on and make sure your sun lamp is configure for a low strength or energy and texture it with a Cloud texture with a Voronoi F2-F1 basis. This you influence on color only at a value of around 20 and set the mix method to add.

Now, set another sun-lamp in for the main land. This one will be for only main-land things and should be 'this layer only', just as the caustics sun should be 'this layer only'.
Bear in mind that this is purely a method for ocean floor caustics, not reactive caustics like if you were to shine a light through a glass and turn it, etc. That you have to ask GOD on - I've never needed that in a render.

Anyway, now that you have some caustics in your scene, we need to add what we've learned so far to the render - brightest boost, mist, blur, custom abberation, etc.
For the sun beams, we will be using the Filter > sunbeams node.

As I've discussed before, in a previous post about the sunbeams node, you can color the beams and you can change there direction beyond your typical values. However, it cannot give you negative beams, which is something I really want! Especially for water, but we can work with this as-is quite well.

In the case for the render above, I had to do two things:
- Use material index to separate the water from the rest of the scene, so we don't get beams coming from rocks (which is not impossible for GOD, but not what we're looking for in this render)
- Use the mist we made to prevent the water from casting beams of it's own accord.

These were simply followed by a Matter > Luminance key node to isolate only the brightest parts of the sea surface to get the beams. Then, you simply intensify the result, if needed, by adding it over itself by a fairly high factor and then adding that in whatever degree over the final image and ta-da.

Just to show you what all the stuff we've talked about looks like together, I made a node-setup image. Now that you know what to do about these, an image like this is no longer a threat! :D


And here is the detail - click to open in a new tab:

And that's it for this post! :D
We are almost done with the series - keep those eyes open for the next one! :D

Have a great one!!

Thank YOU!!!!!!

In : Quick Blog Tutorial 

Tags: jesus  god  holy spirit 

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And if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book.
He which testifieth these things saith, Surely I come quickly. Amen. Even so, come, Lord Jesus.
The grace of our Lord Jesus Christ be with you all. Amen."
Revelation 22:18-21

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Proverbs 30:6

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