I use a program called Simlab Composer 8.1 VR Edition. It works great for softplan renderings. What you do is you can import your 3D model via 3DS or Sketchup file (plus many more file formats) and then setup lighting and materials then setup sky and sun and then render. Please look up their website at www.simlab-soft.com for more details. I have been a user of this program now for about four years and love how easy it is to use. Also by using (if you want to) the VR mode you can interactivly move through your model and interact with doors, lights etc by setting up animations (very easy to do). If you would like more info please go to their website. I was looking at lumion but could not afford it so here is a less cheaper option. For my version it cost me $299 when it was on sale. If you contact them (by giving them your email) they will let you know of sales when they have them.