Abstract: The material found on 3D objects and their parts in our everyday surroundings is highly correlated with the geometric shape of the parts and their relation to other parts of the same object. This work proposes to model this context-dependent correlation by learning it from a database containing several hundreds of objects and their materials. Given a part-based 3D object without materials, the learned model can be used to fully automatically assign plausible material parameters, including diffuse color, specularity, gloss, and transparency. Further, we propose a user interface that provides material suggestions. This user-interface can be used, for example, to refine the automatic suggestion. Once a refinement has been made, the model incorporates this information, and the automatic assignment is incrementally improved. Results are given for objects with different numbers of parts and with different topological complexity. A user study validates that our method significantly simplifies and accelerates the material assignment task compared to other approaches.