Modeling a free-form 3D-surface from a single view has been a widely pursued problem. The existing schemes are either fully-automatic shape-from-X techniques or involve adept interaction from the user but little or no geometric (photometric) basis. We propose a novel scheme of interactive modeling of free-form lambertian surfaces where the solution obtained is consistent with the Shape from Shading model. To this end, a reinforcement learning based scheme has been adopted which allows user intervention at any stage of the algorithm to guide the SFS solution to a global minimum.