I know this is a very general question but I am actually having an issue and I did not know how to verbalize it in the form of a question. Please have a look at my image.
Have you tried messing with your directional light settings? (light source)
Yes it still gets those dark shadows at the bottom of al the geometry at the ground.
Take a look at this video:It goes in dept and the proper scene set up for accurate lighting and the essentials to know about nearly every light source.
It seems this problem may have existed in the content creation. Back to the drawing board. By the way that video is really helpful, thank you!