3D models in still image artwork

Have you ever wounder how 3D models are used in 3D artwork, then below is a small example of how 3D models are used in 3D artwork.

Lets say you have a 3D scene that requires a 3D model. Like the image below

Ok it looks empty and could do with a good size 3D model. So using a 3D modeling program a 3D model would be created for this scene. Like the one below

Now with the 3D model fully created it would be put into the 3D scene like the image below.

Here is the completed image. With the 3D model in the scene.