Making of 'Deep Fish'

INTRODUCTION

In this making of I'll try to show how the image "Deep Fish" was created, and why I never make the effort to get the final render out of the 3d program, and prefer to use compositing. Why did I create the image? Well, I was inspired by a wonderful film about life in the deepest seas by the BBC (British Broadcasting Corporation in the UK), which I saw on the Television. I think it was called "The Deep", but I'm not sure. The ultimate goal was to create the dark and gloomy atmosphere, found at the bottom of the ocean. One of the main difficulties of this was to make the image dark enough (because there is no light at such depths), but still to leave some visible details so you could see the form of the fish. I began by making two sketches, the first for the modelling and the second for the colour and composition of the scene.

MODELLING

I used 3dsmax for this work, but the main principles are the same in all 3d packages. It is also good to get into the habit of using sketches for modeling, because you can work without the fear of losing the models main proportions. The modeling wasn't too hard. I created the box, converted it to editable poly and then just added, moved and welded edges polygons and vertexes. Here is the wire of the final model before subdividing:

I began the modeling using 'quad' (4 sided) polygons, but I converted the mesh to 'tri's' (triangular polygons) later because I didn't want it to be too smooth after subdividing. The next part was very unpleasant for me; unwrapping the model for texturing. I used the unwrap UVW 3dsmax tool, it was a boring, but easy and rather long process, however, it was necessary to get the best results. Here are the UVWs after unwrapping:

I then began to paint textures using Photoshop. First of all, I'm a 2d artist, and I usually use a 3d program as a 'plugin' for Photoshop or Painter. Painting of the textures was therefore much more interesting for me than the modeling or unwrapping stages. I ultimately ended up with three maps: Diffuse (or colour map), Displacement map and the SSS map (sub surface scattering). The SSS map was basically a slightly modified diffuse map. It was necessary to paint the separate SSS map so I could imitate the bones inside the fish, where the body is slightly transparent. I initially wanted to create the displace map using ZBrush, but it is much easier for me to paint it in Photoshop, and I was so satisfied with the first test renders of the displacement I forgot the idea of creating it with ZBrush altogether.

Color Map

Displacement Map

I then modeled the bones for the back, using the same edit poly tool. I didn't pay too much attention to them as they are not the primary objects of the scene, so the model was kept very simple:

I knew that there could not be any seaweed at such depth, but I added some strange things hanging from the bones of the fish, to make the image a little bit more atmospheric and interesting. They were painted in Photoshop as a simple black and white mask and rendered on the planes.

A FEW WORDS ABOUT THE LIGHTING SETUP

I used a few omni lights to make the light appear to be coming from the 'fishing-rod', and a HDRI image to light the body of the fish. Then finally I began to output renders. From the beginning I knew that I wouldn't need to render the whole scene in one final image, I wanted to render different layers to composit them at a later stage. For the rendering I used Vray, because it can easily export out the separate layers. In all, approx. 16 different layers were used (some for the fish, some for the back, and a separate layer for the plankton). I prefer to use separate layers because I can colour correct each of them separately, without adding unnecessary time to the rendering process. I can add or remove the reflection, lights or refractions taking only seconds instead of hours. This is a very convenient method, especially when you render large images with GI which can take a very long time. The main layers for the fish were diffuse, raw GI, raw light, reflections, refractions (sss). I even rendered three different refraction layers so I could achieve different effects, either to make the whole fish more transparent, or to light only the thin parts like the fins. Some layers:

Fig 10

Diffuse

Fig 11

Raw GI

Fig 12

Refractions

Fig 13

Refraction

You can use any compositing software to gather the final image, including Photoshop. I prefer a node-based compositing such as Shake or Nuke. The way to mix your layers is very simple: you should multiply raw gi and diffuse and add reflections, refractions and light (screen in Photoshop). Here you can see the result of mixing main layers of the fish without any correction:

There are also two very useful and quick rendered layers: Z-Depth and 'Normals'.

Fig 15

Z-Depth

Fig 16

Normals
You can use 'Normals' to correct any of your layers, for example to light them from any side using the R (red),G (green), or B (blue) channel of the 'Normals' layer as a mask for colour correction. Here is an example; the left part of the image is the rawGI layer, and the right part was corrected using Normals layer.

The z-depth layer is used to make the difference between the farther and closer objects of the scene, and it was quite useful to imitate the water.

I rendered the bones for the back the same way, then I rendered the plankton layer (I used a particle cloud to generate it). I rendered the blind eye of the fish separately, which gave me all the necessary materials for compositing, then I could shut down 3DSMax. Now all I had to do was to colour correct the layers to create the mood in the image. And here is the final result:

As you can see it is pretty far removed from the original render images. I didn't want to show you a step by step tutorial how to create the same image, but the main idea of my tutorial was to show you the benefits of compositing, I hope you could save hundred hours of rendering time using these layer compositing techniques.