Basic concepts for the Aurora Imaging Library 3D Model Finder module

The basic concepts and vocabulary conventions for the Aurora Imaging Library 3D Model Finder module are:

3D model finder context. An Aurora Imaging Library object that stores the model for which to search. The 3D model finder context also stores global search settings that apply to the search algorithm.
Bounding box. The smallest axis-aligned box that contains the ideal geometric shape of the fitted model at the location of an occurrence.
Central axis unit vector. A vector of unit length that points along a cylinder model's central axis. It points from the center of the cylinder's first base towards the center of its second base.
Fit distance. The maximum distance from the occurrence at which a point can be included in the fit.
Inlier points. Points in the point cloud that are considered part of a model occurrence. A point must be within the fit distance from the surface of the occurrence to be considered an inlier.
Model. The information that defines the pattern of points to find in the point cloud. The 3D Model Finder module supports box, rectangular plane, cylinder, sphere, and surface models.
Model coverage. The percentage of the model's surface found in the occurrence.
Occurrence. An instance of the model found in the point cloud.
**Point cloud.**A set of 3D points representing objects in a scene.
Reference direction. The position of the 3D sensor or the direction of the 3D sensor's line of sight relative to the acquired point cloud.
Reserved points. Points that are reserved in an area around an occurrence; they are considered part of the occurrence but are not used when calculating the fit. They cannot be considered part of any other occurrence.
**Root-mean-square (RMS) error.**A measure of how well the points in an occurrence fit the model. A perfect fit gives a root-mean-square error of 0.0. [Image: 3dmod_rms-error-eq.png]
Score. A measure of how well an occurrence matches a model. The score is defined as the model coverage.
**Working coordinate system.**The implicit real world coordinate system used to express the coordinates of 3D points in a point cloud. Each point cloud container has its own working coordinate system.