Reliable estimation of the reflector dip serves as a fundamental and essential tool for subsurface structure interpretation from 3D seismic surveys. We have developed a new method for accurate dip estimation, which consists of two major components. First, the curvature/flexure concept is adapted from the traditional reflector geometry analysis to work for the seismic waveforms, denoted as the waveform curvature and waveform flexure, respectively. Physically, both of them are capable of measuring the most and least apparent variation of the local waveforms in a seismic profile, and thus the corresponding measuring orientations represent the normal and dipping directions of the seismic reflectors, respectively. Second, the complex seismic trace is incorporated into our workflow of waveform curvature/flexure analysis to enhance the accuracy of dip estimation in the presence of seismic noises, especially in the zones of weak reflection intensity, such as zero crossings. The added values of our method are verified through various applications, such as horizon tracking and fault detection, to two 3D seismic data sets, one from the Netherlands North Sea and the other from the Great South Basin in New Zealand that is rich of faults. The results not only demonstrate the good accuracy of the generated dip vectors in guiding the seeded horizon tracking, but they also hold great potential for assisting seismic interpretation in more ways, such as structural-oriented filtering and attribute analysis.