1. A method comprising: illuminating a first plurality of measurement sites of one or more semiconductor wafers with illumination light generated by an illumination source, the first plurality of measurement sites having known variations of at least one process parameter, structural parameter, or both; detecting light collected from each of the first plurality of measurement sites in response to the illumination light with a spectrometer; generating a measured spectral response of each of the plurality of measurement sites from the light detected by the spectrometer in accordance with at least one metrology technique, the measured spectral response comprising a first amount of measurement data; determining an expected response model of each of the at least one known process parameters, structure parameters, or both; determining an input-output measurement model based at least in part on the first amount of measurement data; training the input-output measurement model based on parameter values determined from the expected response model; receiving a second amount of measurement data associated with measurements of a second plurality of sites using the at least one metrology technique; determining at least one process parameter value, at least one structural parameter value, or both, associated with each of the second plurality of sites based on a fitting of the second amount of measurement data to the trained input-output measurement model; and communicating an indication of the at least one process parameter value, the at least one structural parameter value, or both, to a semiconductor fabrication tool that causes the semiconductor fabrication tool to adjust one or more parameters of a fabrication process of the semiconductor fabrication tool to achieve a desired output from the fabrication tool.