For the specific assets in the environment, I used 3D software to render the channel and later separated some areas in Photoshop (Fig.08). This made things much more convenient whilst allowing me to move on to the next step (Fig.09).
Here is a finished image with GI romance. I decided to finish my whole work using this image as a base (Fig.10).
I shaped some rough atmospheric effects in black and white to achieve the mood (Fig.11), and kept the whole image in the correct range. It was vital that a layer of ash was present to hold the whole image together better (Fig.12).
In the channel just created, colours were added to every large asset. Generally, I created a new layer on a black and white draft and added colours via the "Multiply” layer option (Fig.13 – 14).
I then created a new layer, adding the details such as the iceberg, icicles on the sunken boat, the characters' coats, blurred movement of the wings on the helicopter, and so on (Fig.15 – 16).
Here I moved back to the whole asset and added more details. For example, some frost was added to adjust the atmospheric effects. For newly created layers, the Colour Dodge layer option was utilised to show the light source, such as those shown on the windows of the mobile machinery, as well as on the headlights and so on (Fig.17).