The occultation radiometer ORA was designed to perform measurements of O3, NO2, H2O, number density, and aerosol extinction altitude profiles in the Earth's atmosphere through the occultation method viewing the full solar disk. The experiment was mounted on the EURECA satellite and measured the relative transmission of light during about 7000 orbital sunsets and sunrises from August 11, 1992, to May 13, 1993. The spatial inversion algorithm developed to retrieve the total extinction altitude profiles from these data is described here. It is shown that the signal measured by an instrument having a large field of view can be successfully processed to give a much better altitude resolution than the one related to the angular size of the Sun. The main difficulties concern the inclusion of all refractive effects, the application of a new inversion scheme and its associated mapping strategy to refine the aerosol layer detection. The algorithm applies to fully nonlinear occultation experiments requiring global and nonheuristic inversion schemes.¿ 1997 American Geophysical Union