Diagrams illustrating the procedure used to evaluate the fidelity of interpolated surface elevations. In panel (a), the original (blue) elevation data have a uniform resolution. In panel (b), the resolution of the densified (red) elevation data decreases from top to bottom, which mimics the resolution of elevation data in a simple cylindrical projection. In panel (c), the interpolated (green) elevation data were obtained by interpolating the densified elevation data to the resolution of the original elevation data. In panel (d), a flowchart summarizes the procedure, where x_ori and x_densi denote the x-coordinates of the original and densified elevations, h_ori, h_densi, and h_interp represent the original, densified, and interpolated elevations, and f_ori and f_densi indicate the relations (denoted by “func”) between the x-coordinate and elevation for the original and densified datasets.