Machined surface quality, key aspect of milling process performance, is affected by chatter vibration that produces distinctive marks on the surface. While several works have been proposed on the prediction of the machined surface in stable condition, surface under chatter vibration has not been extensively studied. This paper investigates chatter marks generation mechanisms focusing on the surface spectral proprieties. The generation of the surface profile can be regarded as a problem of sampling at the tooth pass frequency (in time domain) and reconstruction (in spatial domain) of the cutting tool displacements. Using this correlation, two main effects (aliasing and pseudo moiré) causing chatter marks are highlighted and specific formulations proposed. The method was validated by a numerical investigation, based on a surface generation model coupled with a time- domain simulator of the milling process. Finally, the method was applied to two experimental case studies.