  Digitizing physical objects into the virtual world has the potential to
unlock new research and applications in embodied AI and mixed reality. This
work focuses on recreating interactive digital twins of real-world articulated
objects, which can be directly imported into virtual environments. We introduce
Ditto to learn articulation model estimation and 3D geometry reconstruction of
an articulated object through interactive perception. Given a pair of visual
observations of an articulated object before and after interaction, Ditto
reconstructs part-level geometry and estimates the articulation model of the
object. We employ implicit neural representations for joint geometry and
articulation modeling. Our experiments show that Ditto effectively builds
digital twins of articulated objects in a category-agnostic way. We also apply
Ditto to real-world objects and deploy the recreated digital twins in physical
simulation. Code and additional results are available at
https://ut-austin-rpl.github.io/Ditto
