Underwater Compositing and FX Help

As you my have noticed on my website. I am a huge fan of underwater environments. I thought it might be helpful if I created a page to help out, and give pointers on how to build them. I'll start by creaking down real life ocean environments, and showing how we can apply features from real life onto our scenes.

If at any point you would like to read more about the oceans, here are some links:

National Ocean Service: HERE

World Atlas: HERE

 

B&H: HERE

Let's start with understanding the different layers of the ocean. As one of the most important parts of creating a scene is the lighting. It's important to keep in mind at which depth of the ocean or body of water you are building your scene. As depending on how deep the scene is located, the amount of light in the scene will change. There are five layers of the ocean:

Epipelagic Zone: The zone of the ocean that is considered the surface layer. Most light will be refracted and visible at this layer. This is the layer of the ocean that most ocean life is located. Coral reefs, tropical fish, etc. This zone ranges from 0 to 656 feet below the oceans surface. Keep in mind that with the deeper you go into the ocean, the colder the water becomes, and the light becomes more diffuse and less direct.

Mesopelagic Zone: You are now entering ....The twilight zone. Only very faint rays of light reach this level of the ocean. This is also where more creatures that live without the sun start to live. Such as swordfish. This layer extends to 656 to 3,281 feet deep. 

Bathypelagic Zone: This zone is also called the dark zone. It reaches between 3,281 and 12,124 feet in the ocean. Visible light is only created from the creatures living at this depth, and any man made devices. Most sea creatures living here are red or black because of living without the sun. Gulper eels, Angler Fishes, Vampire squids, etc live near the thermo-vents on this layer.  

Abyssopelagic Zone: This is where the great abysses of the ocean exist. This zone extends from 13,124  and 19,686 feet. At this depth there is no natural light, and the temperature is below freezing. Only starfishes, and squids can withstand the pressure at this depth. This is also the layer of the ocean that touches the ocean floor.

Hadalpelagic Zone: The Marina's Trench exists at this level of the ocean. Once again, no natural light reaches this level, and everything is pitch black. Not many creatures we know about live at this level of the ocean. Mostly Just Decapods and Amphipods exist here. This layer of the ocean extends from 19,686 to 36,100 feet.

Now after a brief biology lesson, let's step back into 3D. As always, in 3D space our 3D cameras act like life cameras, and our 3D lighting is based on real world lighting. Let's study how what makes underwater shots difficult in real life. 

  • Water absorbs light. Therefore, the more water, the less light. The farther away from the light source, the less direct the light. Also, keep in mind that water particles refract blue light, and absorb red light. Therefore, red colors underwater are going to be less visible.

  • The refractive index of water is different from air so much so, that as humans we have a hard time judging distances underwater. Things seem bigger (25%) than they actually are. 

  • Water reduces contrast and sharpness of objects. So most objects in your scene will be blurry.

  • There is not a lot of ambient light underwater. Most of the ambient light is reflected away off of the surface of the water.

 

  • Most water contains phytoplankton which gives a green tint to the water's color.

  • Underwater photographers use strobe lighting to counteract the effects of water reducing the contrast and sharpness of their subjects. As well as angling the camera upwards to capture the overhead light more clearly.

 

  • At the first layer of the ocean(Epipelagic Zone) you'll more than likely be able to capture light beams coming through the top of the water. As well as have a good sense of ambient light.

  • Based on the time of day, more light will travel through the water. In real life, divers take shots between 11am and 2pm. Any shots after these times appear darker than expected.

  • Back-lighting objects with the surface light also helps photographers to center their shots more easily.This also creates more accurate silhouettes.

  • Underwater caverns create a lot of light and shadows. Always keep your main subjects highlighted, and your less important objects in the shadows. However, there is hardly ever any ambient light in caves, so it is important to give your scene back-lighting.

 

Now that we've talked about lighting, Let's talk about underwater terrain.

As we've discussed , water particles absorb red light. However, you may have realized if you are at a beach, the sand is yellow, rocks in caverns are a darkened reddish color, etc. But based on where you are in the world, the composition of the rocks and ground will be different. For example, if you are in Santorini Greece, the sand colors can range from red, yellow, black, or white. This is because of the volcano existing near the island. It is important to take these geographical factors into account when building your scene.

Overall, the color of your terrain is important.  Personally, I find creating and using terrain that is a yellowish, grey, to light red color works the best. This works for me because it allows the blue tones of the water to appear more vibrant, and match the scene correctly.  But honestly, it depends on the environment you are building.

Almost anything can exist on the ocean floor. From volcanoes, shipwrecks, trenches, and more. 

The study of underwater terrain is called Bathymetry. If you would like to read more about it, here is the link to the Wikipedia article: HERE.