Automated compact parametric representation of impact craters

We have developed a procedure for the measurement and automated parametric representation of 3-D impact craters. The 3-D stucture of the crater is measured using a low-coherence optical interference technique and the parametric representation achieved in a two-step procedure. Sobel edge detection and morphological operations are used to define rigorously the impact region. The parameter set is defined with respect to a coordinate system whose origin and orientation are uniquely determined from the data. Subjective, arbitrary choices for this position and angle are thus eliminated and the coefficients of the Zernike polynomials are calculated by direct integration over this region to produce a parameter set. This set allows the representation of the three-dimensional geometry by a small set of numbers. Results are presented for impact craters generated at DERA Fort Halstead by the penetration of shaped charge jet particles. It is shown that the agreement between the crater profile generated by the Zernike parameter set and the real crater is very good.