  In the real world, we often come across soft objects having spatially varying
stiffness, such as human palm or a wart on the skin. In this paper, we propose
a novel approach to render thin, deformable objects having spatially varying
stiffness (inhomogeneous material). We use the classical Kirchhoff thin plate
theory to compute the deformation. In general, the physics-based rendering of
an arbitrary 3D surface is complex and time-consuming. Therefore, we
approximate the 3D surface locally by a 2D plane using an area-preserving
mapping technique - Gall-Peters mapping. Once the deformation is computed by
solving a fourth-order partial differential equation, we project the points
back onto the original object for proper haptic rendering. The method was
validated through user experiments and was found to be realistic.
