In Zootopia, the studio had trouble rendering certain animal hairs, specifically white hairs on animals like the honey badger. The polar bear fur also caused big issues as the fur was almost translucent/transparent, giving no color to the polar bear's coat. The studio had to understand the way light entered and scattered through the fur to create a white coloring.
Add to @maewang00's comment, Kersavage, the visual effects supervisor of Disney said: “We have a honey badger in the film and it has some white fur on it and it’s very opaque. But then we also have polar bears and their fur is actually more translucent, almost transparent, and you can’t really see any color in it. It’s more about the way the light actually goes through the polar bear’s fur and scatters through the rest of the fur that creates the white effect.” “It would have been challenging for us to re-build the actual hair follicles for every species, so we decided to take a shader approach to this and try to see if we could replicate through some shader principles the ways we can create fur that has the right opaqueness or the light passing through.”
I think it's really interesting that they chose to use human hair to model the fur of the animals. Even though animal fur typically looks really different than human hair, I do feel like the models really work for some of the animals. Looking at this image, it seems like the fur really works for Judy and Nick, but Flash's hair does look a little bit unrealistic for a sloth, in my opinion. Anyone know if the animals that have more accurate looking models are the ones that actually have fur that is more similar in structure to human hair?