A method for monitoring a first nanometric structure formed by a multiple patterning process, the method may include performing a first plurality of measurements to provide a first plurality of measurement results; wherein the performing of the first plurality of measurements comprises illuminating first plurality of locations of a first sidewall of the first nanometric structure by oblique charged particle beams of different tilt angles; and processing, by a hardware processor, the first plurality of measurement results to determine a first attribute of the first nanometric structure.