A ranging system using spatially continuous filtering techniques to constrain ranging measurements, thereby improving ranging calculations between a bottom-hole-assembly and at least one target well. By taking advantage of the spatial continuity of the wellbore geometry, a quality check of a ranging measurement is performed using ranging measurements acquired at prior depths. Thus, the methods described herein provide improved ranging and direction estimates, as well as prediction of ranging and direction of the target well ahead of the bottom-hole-assembly.