One of the great advantages of being a 3D artist is that you can do just about anything to a scene once it has been built. My fans have long come to expect night versions to accompany my brighter landscapes (because darker images work well as wallpaper). I have even created series depicting one landscape at different times of the same day/night. Changing the seasons is an order of magnitude more complicated however so I have only done a few "Four Seasons" series. It's a lot more complicated than just changing the sun angle. My first seasonal series was in 2005 (the "Wood" series) and I think I've come quite a long way since. For the blooming tree buds I replaced the bigger leaves from the Autumn and Night (Summer) with smaller flowers, which allows a lot more light to filter through.. Created and rendered using VUE/Plant Factory Enterprise.