A method for image processing includes providing a microscopic image of a structure fabricated on a substrate and computer-aided design (CAD) data used in fabricating the structure. The microscopic image is processed by a computer so as to generate a first directionality map, which includes, for a matrix of points in the microscopic image, respective directionality vectors corresponding to magnitudes and directions of edges at the points irrespective of a sign of the magnitudes. The CAD data are processed by the computer so as to produce a simulated image based on the CAD data and to generate a second directionality map based on the simulated image. The first and second directionality maps are compared by the computer so as to register the microscopic image with the CAD data.

A system can locate patterns for measurement in a captured Scanning Electron Microscope (SEM) image. The system can include a processor circuit that can be configured to generate a target pattern from a layout of a semiconductor device, and configured to generate a virtual image that corresponds to the target pattern, wherein elements of the virtual image less than completely overlap the corresponding portions of the target pattern, and configured to locate portions of a captured SEM image of a fabricated semiconductor device that match the elements of the virtual image.

Build material handling unit for a powder module for an apparatus for additively manufacturing three-dimensional objects, which apparatus is adapted to successively layerwise selectively irradiate and consolidate layers of a build material which can be consolidated by means of an energy source, wherein the build material handling unit is coupled or can be coupled with a powder module, wherein the build material handling unit is adapted to level and/or compact a volume of build material arranged inside a powder chamber of the powder module by controlling the gas pressure inside the powder chamber.