Three-dimensional reconstruction of fracture surfaces: Area matching algorithms for automatic parallax measurements

This paper describes two solutions for systematic measurement of surface el evation that can be used for both profile and surface reconstructions for q uantitative fractography case studies. The first one is developed under Kho ros graphical interface environment. It consists of an adaption of the almo st classical area matching algorithm, that is based on cross-con elation op erations, to the well-known method of parallax measurements from stereo pai rs. A normalization function was created to avoid false crosscorrelation pe aks, driving to the true window best matching solution at each region analy zed on both stereo projections. Some limitations to the use of scanning ele ctron microscopy and the types of surface patterns are also discussed. The second algorithm is based on a spatial correlation function. This solution is implemented under the NIH Image macro programming, combining a good repr esentation for low contrast regions and many improvements on overall user i nterface and performance. Its advantages and limitations are also presented .