Basic concepts for the Aurora Imaging Library Metrology module

The basic concepts and vocabulary conventions for the Aurora Imaging Library Metrology module are:

• Active edgels. The edgels within the metrology region that adhere to certain constraints.
• Constructed feature. A geometric primitive that has been mathematically defined or geometrically derived from a set of other features.
• Edge. A curve that delineates a boundary, which can be established from intensity transitions in an image.
• Edgel. Elementary points (or edge elements) within an edge. Each edgel represents an X- and Y-position, and the angular direction of the gradient.
• Fitted edgels. The active edgels that are used to build a fitted feature.
• Geometric tolerance. The acceptable deviation from the definition of a feature, or the acceptable relationship between multiple features.
• Global frame. The metrology template's default reference frame.
• Gradient angle. The angle between the target image's horizontal axis and the edge's perpendicular direction (from black to white) at each edgel location.
• Iterative fit. The calculated fit resulting from one of the iterations during the iteration process.
• Local frame. A constructed reference frame.
• (Physically) measured feature. A geometric primitive that can be physically measured using the edgels in the metrology region.
• Metrology context. An Aurora Imaging Library object that stores all features and geometric tolerances of the metrology template, and global processing settings.
• Metrology region. The delimited area in the target image from which to select the edgels used to establish a physically measured feature. The features with which to build constructed features can also have a delimited metrology region.
• Metrology region orientation. The alignment of a metrology region, with respect to a reference frame.
• Metrology template. The set of all features and geometric tolerances.
• Output frame. The coordinate system in which feature results are returned.
• Parametrically constructed feature. A geometric primitive that has been mathematically defined, rather than geometrically derived from a set of other features.
• Reference frame. The coordinate system in which features are defined and to which they are relative.
• Target image. The image in which to extract physically measured features, build constructed features, and verify geometric tolerances.
• Template reference. An image (or result buffer) that represents an example of a target image, used to help build or modify a metrology template.