You can apply a Ptex file or an image file as a displacement map to sculpt the surface of your model in Mudbox.
If you’re applying an image map, the model must have well-defined UV texture coordinates. (See UVs overview and Prepare a model for sculpting.) If the target mesh has no texture coordinates, you can use Ptex to sculpt the surface, however the topology of the target model must match the topology in the Ptex file.
Mudbox supports displacement maps of 8, 16, and 32-bit images. For best results, use displacement maps that are 16-bit or 32-bit floating point as they better represent the fine details on a sculpted model. See also Image bit depth and texture extraction.
Sculpting with displacement maps lets you:
The low resolution model can be optimized for animation and have a different topology from the high resolution version. You extract the displacement map from the high resolution source model to the low resolution target model (even if it has different topology) so the displacement map can be correlated to the UVs on the low resolution model. Mudbox supports the extraction of displacement maps on models with UVs that exist outside the 0-1 range.