Blender is an integrated 3D suite for modeling, animation, rendering, post-production, interactive creation and playback. Blender has its own particular user interface, which is implemented entirely in OpenGL and designed with speed in mind. Great for making 3D stills, animations, models for games and interactive content.
K3D is an advanced 3d animation program designed from-the-ground-up to generate motion-picture-quality animations with RenderMan compliant engines. Record and playback, tutorials, unlimited undo/redos and more features to make 3d rendering as ease.