Registration provides a way to "stitch" more than one surface or image together. It relies on the fact that surfaces and images in Phase MOSAIC contain a global coordinate system. Each surface or image is compared pixel by pixel relative to this coordinate system. Because of this, Phase MOSAIC provides great flexibility in modifying the coordinate system for each surface or image. For surfaces, overlapping pixels are fitted with Zernike polynomials and used to adjust each surface to merge the data sets. Each Zernike polynomial uses the same normalization radius and coordinate system origin. Surface height values are averaged to produce the final surface height. Statistics for the surface height values at each global coordinate system position can be generated, see Pixel overlay statistics. For images, color values are compared and averaged to produce the final pixel data. See Frequently Asked Questions.
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Attach a global coordinate system to each individual subaperture surface
- This can be done by matching fiducials to real world coordinates.
- This can be done using knowledge of translations from a motion system.
- The origin of the global coordinate system is used to define the center of the Zernike unit circle for allowable aberrations
Determine the allowable aberrations to adjust between all of the subapertures
- These are the allowed “degrees of freedom” in Zernike polynomial space
- These aberrations are usually due to misalignments between measurements of each subaperture
- The origin of the global coordinate system is used to define the center of the Zernike unit circle for allowable aberrations
The algorithm will adjust the aberrations of each subaperture to match in the overlap region
- Subapertures are stitched sequentially
- Want the area of overlap to be as large as possible for each stitch operation
- The order of subapertures can be chosen to maximize the overlap area for each stitch operation while distributing errors over the unit circle
The adjusted surface height data is overlaid in the global coordinate system
- Remove the allowable aberrations from the full stitched surface (optional)