In one embodiment, apparatus and methods for determining a parameter of a target are disclosed. A target having an imaging structure and a scatterometry structure is provided. An image of the imagingstructure is obtained with an imaging channel of a metrology tool. A scatterometry signal is also obtained from the scatterometry structure with a scatterometry channel of the metrology tool. At leastone parameter, such as overlay error, of the target is determined based on both the image and the scatterometry signal.