  Longitudinal and transverse transition form factors for most of the four-star
nucleon resonances have been obtained from high-quality cross section data and
polarization observables measured at MAMI, ELSA, BATES, GRAAL and CEBAF. As an
application, we further show how the transition form factors can be used to
obtain empirical transverse charge densities. Contour plots of the thus derived
densities are shown and compared for the Roper and S11 nucleon resonances.
