Systems and methods using imaged device patterns to measure overlay between different layers in a semiconductor manufacturing process, such as a double-patterning process. Images of pattern features are acquired by scanning electron microscopy. The position of a patterning layer is determined using positions of pattern features for the patterning layer in the images. A relative position of each patterning layer with respect to other pattern features or patterning layers is determined in vector form based on the determined pattern positions. Overlay error is determined based on a comparison of the relative position with reference values from design or simulation. Overlay can be measured with high precision and accuracy by utilizing pattern symmetry.