Adaptable Siemens Star Targets for Reliable and Standardized Spatial Resolution Measurement under DIN 18740-8

Abstract. Precise, standardized assessment of spatial resolution is essential for optical remote sensing. We present an adaptable Siemens-star methodology aligned with DIN 18740-8 that enables reliable, reproducible modulation transfer function (MTF) measurements across simulation, laboratory, and aerial (UAV) scenarios. The target geometry is parameterized by star frequency and ground sampling distance (GSD), providing a simple sizing rule for practical deployment. Design variants include multiple segment counts (8–48 Hz) and four gray-level contrasts to mitigate overexposure, a frequent field issue that biases MTF. A phase-based center-detection algorithm — applicable to square- and sinusoidal-type stars — ensures robust centering, a prerequisite for valid MTF estimation. Results show highly consistent MTFs across all configurations: average deviations of 0.007, 0.006, and 0.011 line/pixel for simulation, DSLR, and UAV data, respectively. Center localization exhibits an average two-dimensional error of 0.074 pixels over twenty target variants, confirming numerical stability and implementation accuracy. The scalable vector graphics (SVG) design ensures pixel-exact reproducibility and straightforward scaling to different GSDs while offering practical advantages in production cost, transport, and deployment. Overall, the approach establishes Siemens-star targets as a cost-effective and field-ready alternative to conventional methods, providing standardized procedures, robustness to non-ideal imaging conditions, and direct applicability to both RGB and monochrome systems in operational photogrammetry and remote sensing.
SVG-designs of all Siemens stars as well as the ”Resolving-Power” tool to perform the measurements can be downloaded from https://macs.dlr.de/box/resolvingpower.html.