Training a descriptor network includes obtaining a first image of a scene from an image capture device, applying a sensor sensitivity model to the first image to obtain shadow-invariant image data for the first image, and selecting a first patch from the image. Training a descriptor network also includes obtaining a subset of the shadow-invariant image data corresponding to the first patch, and training the descriptor network to provide localization data based on the first patch and the subset of the shadow-invariant image data.