Any recommendations for a good landscape planning/visualization app for iMac?

I would like to do some landscape planning and am looking for a good app for iMac that will help me do 3D visualization (preferably through multiple seasons). I prefer something that will let me take pictures of what is already there and then enhance rather than having to first draw in the existing features from scratch.

It would be nice if the app can take into account shade caused by existing trees and structures as a couple of the areas I want to landscape are shaded by both trees and buildings (so it’s hard to get grass to grow). I would also like it to be able to do things like masonry retaining walls, rock water features, etc…

So… suggestions?