This function offers the ability to search a point cloud and detect registration spheres within the cloud, build the center points (geometry and extracted clouds) for those detected spheres.
Provide the command with the expected sphere diameter, acceptable RMS tolerance, and minimum number of points required, and the command will detect spherical data matching the proposed diameter from the scan data.
Search Tolerance. The maximum allowable deviation for a given point from the desired diameter in order to be considered.
Minimum Point Count. The minimum number of cloud points required to satisfy the tolerance to consider a sphere to be “found”.
An additional final fit can be performed to remove outliers and refine the solution based on the associated instrument station. Enabling the option to perform a “Final Fit” will use the ASTM E3125-17 fitting algorithms. The point cloud data is filtered so that only a central cone opening angle of 120° is used to compute the sphere and its center point.
Note that the input cloud must be associated with an instrument to establish the line of sight vector used for cloud segmentation as per this standard which then applies a conical outlier rejection strategy to further refine the fit results.
To use the ASTM E3125-17 refinement method:
Enable Final Fit. This check box must be enabled to perform the final fit.
LOS Cone Angle The Line of Sight Cone Angle can be adjusted from the 120 degree default as depicted above.
In addition to the extracted center points, additional optional constructions can be performed for each extracted sphere location:
Create Sphere's In Addition to Points
Create Extraction clouds