Radar interferogram
= Radar interferogram
{title2=$\Delta\phi=\pm4\pi d_{\mathrm{LOS}}/\lambda_r$}
An image of the relative radar phase between co-registered coherent observations. A displacement changes the two-way path length, giving phase change proportional to $4\pi d_{\mathrm{LOS}}/\lambda_r$, with sign set by the adopted range convention. A full wrapped phase cycle therefore corresponds to half a radar wavelength of <line-of-sight displacement>. Orbital geometry, topography, atmospheric delay and scattering changes must be separated from deformation; a fringe is not uniquely an elevation contour or an earthquake displacement.<Interferometry by NASA>[Interferograms, half-wavelength fringes and removal of orbital and topographic contributions]{ref}