  Mathematically representing the shape of an object is a key ingredient for
solving inverse rendering problems. Explicit representations like meshes are
efficient to render in a differentiable fashion but have difficulties handling
topology changes. Implicit representations like signed-distance functions, on
the other hand, offer better support of topology changes but are much more
difficult to use for physics-based differentiable rendering. We introduce a new
physics-based inverse rendering pipeline that uses both implicit and explicit
representations. Our technique enjoys the benefit of both representations by
supporting both topology changes and differentiable rendering of complex
effects such as environmental illumination, soft shadows, and interreflection.
We demonstrate the effectiveness of our technique using several synthetic and
real examples.
