Range-Doppler imaging is the basic method of inverse syn- thetic aperture radar, which is based on the uniform rotation of targets. Nonuniform rotation can occur to maneuvering targets, which produces smeared images. A constantly acceleratively rotating model is used here instead of the traditional uniformly rotating model. The generalized mar- ginal integration along straight lines with varying slopes is calculated over the time-frequency plane. The imaging quality is improved by using the new method. © 1996 Society of Photo-Optical Instrumentation Engineers. Subject terms: inverse synthetic aperture radar; time-frequency distribution.