A method is provided for controlling an additive manufacturing process in which a layer of resin is deposited on a build surface and selectively cured via selective application of radiant energy so as to define the geometry of a cross-sectional layer of the component, such that uncured resin remaining on the build surface after curing defines a negative structure of the layer being cured. The method includes: using an imaging apparatus to produce an image of the negative structure; evaluating the image of the negative structure and controlling at least one aspect of the additive manufacturing process with reference to the image of the negative structure.