The materials I used are mostly made using the textures from cgtextures.com; it is a really awesome site!
I stitched some of them together in Photoshop, for example this metal floor texture.
And here´s a bloody secret: although I used custom textures and displacement maps a lot, there is not a single UV-unwrapped object in the scene, except for the tentacles of course.
I did not use UV mapping because it would have taken up much more time than what I had on my hands (since I was working alone and had to build the entire scene from scratch), and also due to the abundance of geometric detail in the submarine.
As soon as I had finished the 3D scene, I calculated the distance from the 3D people to the camera, and using this information, did a proper photo shooting with my actors (for whom I of course had prepared the clothing beforehand).
Here are the raw shots...
That's me, motivating the young navigator :)
Also starring in the below picture - my grandfather as the Captain. He used to serve in the Navy when he was young, so the main problem when photographing him was not to shake the camera too much while laughing at the ridiculous amount of curse words uttered by him through the smoking pipe during the shooting.... :)
On the floor you can see a measuring tape. I used it to set the camera distance precisely as calculated from the 3D scene.
Here is the tech guy...
The interesting part here is probably his uniform and his tool belt. It is basically all made from used clothes from the army surplus shop with some modifications, and some tools from the garage + some black shoe polish to make him look dirty.
And here is the radio guy.