Creating the fur
Despite all the hard work that goes into every detail of the illustration, the fur was essential to sell the believability of the image, so we took it with special care.
In addition to creating a height map texture that would be generated in 3ds Max, we modeled small planes (to be later converted into Splines) that would dictate the flow and direction of the hairs. It's important to have in mind a hierarchy of Splines: the fur that will be generated later will take into account the order in which the Splines were created and the direction of the extrusion from the original vertices. We were also careful to model the rats with an even topology, so that the fur generated from their bodies' vertices ended uniformly.
Creating a hierarchy of Splines to generate the fur
"The order of the Splines affected the direction of the fur, so extra care was taken to make it as close as possible to the concept of the image"
We used the native Hair & Fur plug-in for this part. The hair orientation was done after careful placement of geometry (planes) that had their edges extracted and converted into Splines. The order of the Splines affected the direction of the fur, so extra care was taken to make it as close as possible to the concept of the image. With some test renders we were able to correct and further adjust the hair orientation and size through the Splines.
In order to distinguish one rat from another we used a different configuration in each fur and some specific body parts, such as head, eyebrows and cheeks in a different geometry to allow for better control. Hair Styling was used when a specific adjustment was needed.
Using different fur configurations for each rat
The lighting was a bit tricky; we wanted to make a dark, damp environment that contrasted with the brightly lit street outside, while at the same time lighting the rats from below in an ethereal way. We first lit the environment and then the rats. To do that, we started to place V-Ray lights to simulate the light from the sun and sky while at the same time trying to make the image's details readable.
A small light was placed to simulate the warm rays of the sun, to make the shadows a bit sharper, and the blue sky light was achieved through a combination of a Dome light from outside and 2 V-Ray light planes to simulate scatter inside the sewer. We then added the rats and foreground pipes to see how everything was coming together and noticed that some parts were too dark and not noticeable. A third V-Ray light plane was then created to better simulate the sky light on the rats and make their silhouettes stand before the background.
Placing light to create the right atmosphere
A counter light was also placed on the ground level pointed upwards, to simulate the light bouncing and make some details in the pipes a bit clearer. Two lights were also created to better illuminate the foreground pipes. Every light had shadows except the counter light. In regards to the light coming from below the rats, three small V-Ray light planes were created and placed to make both the left, middle and right main rats stand equally and have proper specular reflections. To achieve the ethereal feel we wanted, all three didn't cast shadows.
The counter light pointing upwards and two foreground lights made the pipes clearer
Texturing the background
After setting the lighting, the background materials were detailed. We wanted to convey a wet, dirty environment. Since it was very dark and we wanted to show some details, every material had a slight reflection, even the concrete and bricks. In order to have more control over them, they had Fresnel activated in the reflections; and most had high IORs.
The wet walls had water running down in some spots, so in order to make that effect visible, the materials were very reflective and had a black-and-white texture applied to the Reflection Glossiness slot. We also rendered some high reflections for the foreground pipes, to later edit them in the areas that we wanted.
The wet walls had high reflection and a black-and-white texture in the Reflection Glossiness slot
"The textures on the hands, ears and noses were tailor made for each model, so no dirty pattern would be recognizable"