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Underwater compositing - Brightest boost

Posted by Marius Oberholster on Thursday, December 11, 2014 Under: Quick Blog Tutorial
Hey all!

Now we're on to part two of the series on underwater compositing. Obviously, I'm no expert at this, but what I do know I do like to share, so I hope you find this helpful.

Personally, I used Blender Render a lot. It is the old render engine in Blender and it does not support caustic light. I remember when I started out with Blender, I really really tried to figure out how to make it make that light, but nothing, haha.

In compositing, you have, in situations like Blender, values that go above 1 and sometimes below 0, but these values are important for things like highlights. Caustic lighting forms part of this excess, if you will, that you really want to highlight, pardon the pun.

See, when caustic light shines through the water, the thickness of the particle matter in the water, makes it stand out and get a very fuzzy glow - sometimes you even get sunbeams to those areas. And that is what I'm going to be showing you today!

Note, these values are rarely above 1, so you will have to be clever about isolation, since it's never just the caustics that glow in isolation, so, we will be taking general brightness values from the image and adding them back over in a blurred fashion.

This is what it looks like without it and the other elements for underwater compositing:

Not bad, but not quite there.

This is what it looks like with all the elements:

The question is of course how to do it - Luminance key!
   In order to isolate certain brightness areas, we need to have some form of cancellation. There are two ways to do this, but I prefer the Matte > Luminance key node. The other is the Converter > ColorRamp node. This output, of only high intensity, we use as a factor input for a Color > Mix node, because we still want color on these brightness points.

Make sure you connect it to only color back the areas that have been isolated. Now add a Filter > Blur node and soften it a little. I took it at 1 for both X and Y on a relative value with correction on the Y axis. It may seam extreme, but we only want a hint, not excessive brightness.

You simply now add this blurred result over your original image and you would see something like this for before and after:

It is a slight difference, but makes a huge difference in the feel of the scene. Look at, for example, the difference between the before and after on the honeycomb mesh. There is also quite a difference on the cone and the torus. When you have movement, you will have a soft wavy effect.

Give it a shot and see what you come up with! Be creative!

Have a great one!!!

Thank YOU!!!!!!

In : Quick Blog Tutorial 

Tags: jesus  holy spirit  god  blender  caustics  compositing  underwater 

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