A computer program for comparing irregular two-dimensional forms.

Abstract

A shape comparison of two forms requires a procedure that ensures comparability. A computer program has been written to compute a quantitative measure of shape differences between irregular bounded forms. The curve-fitting procedure, utilizing Fourier's series, is particularly well-suited for two-dimensional closed forms. The program provides several alternate methods to eliminate size difference, ensure a common or neutral center for superimposition and provide a rotational orientation which minimizes shape differences. The program contains numerous user-specified options which control input data transformations, algorithmic processing and output. The algorithmic processing provides: (1) generation of Fourier coefficients based on observed data, (2) two methods of producing Fourier coefficients adjusted for positional orientation, (3) two methods of producing Fourier coefficients adjusted for size standardization, (4) two methods of producing Fourier coefficients adjusted for rotational orientation, (5) a cross-correlation technique which rotationally adjusts two superimposed forms to minimize the shape difference, and (6) various standard statistical measures.