A useful method begins by making the question answerable. Consider an authority asking whether a hillside beside a transport corridor has moved over several years. The following is an educational example, not a completed ViewPiece engagement.
1. Define the quantity
Specify the slope boundary, time interval, expected motion, decision context and the displacement component that matters. InSAR measures change along its line of sight; the engineering question may concern a different direction.
2. Find suitable observations
Identify acquisitions, orbit direction, wavelength, mode, processing level, temporal spacing and rights. Examine whether vegetation, snow or land use changes will preserve adequate coherence and whether both viewing geometries are available.
3. Model the comparison
Co-register complex observations, form interferograms and assess coherence. Estimate topographic phase using an elevation model, check orbit and atmospheric effects, select a defensible reference area, unwrap phase where justified and convert phase to relative line-of-sight displacement using the radar wavelength.
4. Test the inference
Compare with GNSS, levelling, corner reflectors, field inspections, rainfall and geotechnical records as appropriate. Examine residuals, sensitivity to reference selection, gaps and alternative causes. Report where coherence is too weak or geometry too limiting to support a conclusion.
5. Communicate for the decision
Present acquisition dates, coverage, units, direction, uncertainty, excluded zones and the distinction between a remotely sensed pattern and an engineering diagnosis. Only qualified engineering review can establish the safety significance for an asset.