In a seismic velocity analysis, a method that assumes a constant velocity for the entire path of a ray, allowing the normal moveout (NMO) to be calculated for each seismic trace as a function of two-way travel time (TWTT). Where the correct velocity has been applied for a given reflector, the NMO will appear horizontal on the CVG; if the velocity applied is too high or too low, it will appear curved. CVG is a necessary precursor for stacking.