Deformable 3--D models are used extensively in Computer Graphics and Computer Vision for Visualization, Animation and Modeling. They can be represented either as traditional explicit surfaces, such as triangulated meshes, or as implicit surfaces. Explicit surface representations are widely accepted because they are simple to deform and render. However, for fitting purposes, they suffer from the fact that using them typically involves minimizing a non-differentiable distance function. By contrast, implicit surface representations allow fitting by minimizing a differentiable algebraic distance. However, they have not gained wide acceptance because they are harder to meaningfully deform and render. Here we propose a method that combines the strength of both approaches. It relies on a technique that can turn a completely arbitrary triangulated mesh, such as one taken from the web, into an implicit surface that closely approximates it and can deform in tandem with it. This allows both automated algorithms to take advantage of the attractive properties of implicit surfaces for fitting purposes and people to use standard deformation tools they feel comfortable for interaction and animation purposes. We demonstrate the applicability of our technique to modeling the human upper-body, including face, neck, shoulders and ears, from noisy stereo and silhouette data.