Since the beginning of July Terragen 4 is in free open beta.
Terragen is the software that many artists turn to when they want to render beautifully realistic landscapes, skies or other natural environments. There are some big changes in Terragen 4, including the all-new realtime ray-traced preview, amazingly realistic cloud shading model, lens effects, improved render times.
The beta version is completely free and unrestricted, with all Terragen 4 features available for you to test during the period of the beta. The beta will expire and will no longer run once Terragen 4.0 is released as a final version in the near future.
Learn more on Planeta Software