Realism (arts) - the general attempt to depict subjects truthfully
I like this simple definition of realism in the arts. It's simply an artists attempt to depict the things he/she hears/sees honestly in whatever medium they choose. Ah, but there's a wrinkle in this simple definition. The focus is on one specific artists view of what is real. And as anyone who has been paying attention to 21st century art knows; everyone has a different idea of what is real and what is not.
So, essentially, what we have is a kind of subjective reality by the artist. Because even an exact, photo-like depiction of life still has the artists specific choices about what to include in the image they are creating. Depicting reality is impossible. One can only live reality. However, if you think of Realism as a style like other types of styles, just one that gets how most things in our world look, then I think you have a good idea what is realistic in, specifically, digital art.
Renderosity artists have been creating "realistic" digital imagery right from the beginning. In fact, one of the goals of tools like Poser and Daz 3D is to create models with such realistic shading and materials, that the rendered image gets byond the "uncanny valley" effect and looks like a real person. Of course, there are varying versions of the realistic style being created by Renderosity artists. If you go to the Modo gallery, for instance, you'll find many remarkable renders of objects and architecture:
Historical by Darkglass
Whereas, if you go to the VUE gallery, you'll mostly see beautiful renders of digital environments.
Mill by TerraProject
And in the Poser gallery, you'll find gorgeous renders of people, particularly beautiful men and women.
Aram by DimitriAraujo
In the Art of Renderosity, realism is one of the key aspects of how artists view their work. Certainly, there is a lot of experimentation at Renderosity, but in many ways, Realism is the house style because it has a wide appeal and because it sells better. And, frankly, it's much harder to create a realistic version of a model's face that it is to abstract it with several brush strokes or slashes/blobs of color.
Look through a gallery of 10 selected works (see above) by Renderosity artists done in the realist style. I think you'll find them most interesting. If you want to know more about a particular image or artist. Visit Renderosity.com and search for them under the galleries/artist headings.