Blender is open sourcesoftware. It has a steep learning curve, but does quality work.
Blender has a powerful Python scripting API. Every control in the GUI can be scripted.
Default renderer is "Blender Render". Cycles is a better and newer render engine. It will soon be default.
- Blender Render is a engine
- Cycles is a physically-based rendering engine
Also: 3D concepts, .