Sampling Moiré Method with Oblique-View Correction for Long-Distance Displacement Monitoring of High-Rise Buildings

Vertical displacement monitoring during super high-rise construction requires long stand-off distances and oblique imaging, for which conventional Sampling Moiré Method (SMM) processing suffers projection-scale bias and camera-support drift. This study presents a field-oriented workflow combining intrinsic camera calibration, in-situ marker-plane geometry, SMM phase extraction, and a fixed reference channel. The oblique-view degradation is quantified by a dimensionless period-non-uniformity index that separates uniform projection-scale error from spatial period-gradient error and partitions the tilt/distance space into design zones. Numerical and physical tilt sweeps show that homography rectification and adaptive local sampling keep the RMSE below 0.3 mm up to 60°, where the uncorrected measurement reaches approximately 2 mm; these two strategies are intended for caution/danger-zone geometries, whereas the field workflow used a locally estimated scale correction, consistent with the design case D=58 m (δ=0.59%). A single-run outdoor 50 m three-point experiment shows that differencing against a fixed reference marker reduces the RMSE by 45.7% and approximately 31% at two moving markers. In two non-simultaneous field programmes, the laser rangefinder and corrected SMM were evaluated independently against the same 1–10 mm prescribed sequence. Their ten-level MAE/RMSE values were 0.280/0.303 mm and 0.165/0.207 mm, respectively. Each programme reports accuracy within its own installation and loading arrangement. The results provide short-term evidence for traceable, long-distance oblique-view displacement monitoring during construction.