Mudbox is the first advanced, high resolution brush-based 3D sculpting
software that is built from the ground up to address the needs of the
professional digital sculptor.

Designed by production artists for production artists, Mudbox introduces
new ideas and combines familiar concepts in fresh ways to offer a unique
solution for high-end commercial modeling and design.

With its friendly interface, consistent structure, respect for industry
convention, and a get it done focus, Mudbox is quick to learn and easy to
use, integrating seamlessly with existing pipelines. Digital artists with
previous 3D experience are quickly productive in Mudbox with minimal or
even no orientation.

Mudbox Professional additional features:

Network license option
Unlimited Layers per object
32-bit HDR image support
Smooth UV coordinates

http://www.mudbox3d.com/