| 摘要 |
An assembly that includes a projector and camera is used with a processor to determine three-dimensional (3D) coordinates of an object surface. The processor fits collected 3D coordinates to a mathematical representation provided for a shape of a surface feature. The processor fits the measured 3D coordinates to the shape and, if the goodness of fit is not acceptable, selects and performs at least one of: changing a pose of the assembly, changing an illumination level of the light source, changing a pattern of the transmitted With the changes in place, another scan is made to obtain 3D coordinates. |
| 主权项 |
1. A method of determining three-dimensional coordinates of points on a surface of an object, the method comprising:
providing an assembly that includes a first projector and a first camera, the first projector and the first camera being fixed in relation to one another, there being a baseline distance between the first projector and the first camera, the first projector having a light source, the first camera having a lens and a photosensitive array; providing a processor electrically coupled to the first projector and the first camera; providing a mathematical representation of a shape of a feature on the surface; providing a value for an acceptable goodness of fit; sending a first transmitted light from the first projector onto the object; acquiring by the first camera a first reflected light and sending a first signal to the processor in response, the first reflected light being a portion of the first transmitted light reflected from the surface; determining by the processor a first measured set of three-dimensional (3D) coordinates of first points on the surface, the first measured set based at least in part on the first transmitted light, the first signal and the baseline distance; determining by the processor a first measured subset of points, the first measured subset of points being a subset of the first points on the surface, the first measured subset of points being measured points corresponding to the feature; fitting by the processor 3D coordinates of the first measured subset of points to the provided mathematical representation of the shape of the feature, the fitting including comparing the 3D coordinates of the first measured subset of points to 3D coordinates of a first derived subset of points to obtain a collection of residual errors, the first derived subset of points being a collection of points lying on the shape of the feature, each of the residual errors from the collection of residual errors being a measure of a separation of corresponding 3D coordinates from the first measured subset and the first derived subset, the fitting further consisting of mathematically adjusting position and orientation of the shape to minimize the collection of residual errors according to a minimization rule; determining by the processor a measured goodness of fit, the measured goodness of fit being a mathematically derived quantity obtained from the collection of residual errors; determining by the processor whether the 3D coordinates of the first measured subset of points are acceptable based at least in part on a comparison of the measured goodness of fit to the acceptable goodness of fit; determining by the processor whether the first measured set of 3D coordinates is acceptable based at least in part on whether the 3D coordinates of the first measured subset of points are acceptable; if the first measured set of 3D coordinates is acceptable, storing the first measured set of 3D coordinates; if the first measured set of 3D coordinates is not acceptable, taking steps (a)-(e): (a) selecting by the processor at least one action to be taken and taking the action, the at least one action selected from the group consisting of: changing a pose of the assembly, changing an illumination level of the light source, changing a pattern of the transmitted light, and measuring the feature by illuminating a mechanical probe and imaging spots of light on the probe with the first camera; (b) sending a second transmitted light from a first projector onto the object or illuminating spots of light on the mechanical probe held in contact with the object; (c) acquiring by the first camera a second reflected light and sending a second signal to the processor in response, the second reflected light being a portion of the second transmitted light reflected from the surface or the mechanical probe; (d) determining by the processor a second measured set of 3D coordinates of second points on the surface, the second measured set of 3D coordinates based at least in part on the second transmitted light, the second signal and the baseline distance; and (e) storing the second measured set of 3D coordinates. |
