  Recent progress on the extraction of electromagnetic properties of nucleon
resonance excitation through pion photo- and electroproduction is reviewed.
Cross section data measured at MAMI, ELSA, and CEBAF are analyzed and compared
to the analysis of other groups. On this basis, we derive longitudinal and
transverse transition form factors for most of the four-star nucleon
resonances. Furthermore, we discuss how the transition form factors can be used
to obtain empirical transverse charge densities. Contour plots of the thus
derived densities are shown for the Delta, Roper, S11, and D13 nucleon
resonances.
