Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Improved shift estimates on extended Shack-Hartmann wavefront sensor
  images   An important factor which affects performance of solar adaptive optics (AO)
systems is the accuracy of tracking an extended object in the wavefront sensor.
The accuracy of a centre-ofmass approach to image shift measurement depends on
the parameters applied in thresholding the recorded image; however, there
exists no analytical prediction for these parameters for extended objects.
Motivated by this we present a new method for exploring the parameter space of
image shift measurement algorithms, and apply this to optimize the parameters
of the algorithm. Using a thresholded, windowed centre of mass, we are able to
improve centroid accuracy compared to the typical parabolic fitting approach by
a factor of 3 in a signal-to-noise regime typical for solar AO. Exploration of
the parameters occurs after initial image crosscorrelation with a reference
image, so does not require regeneration of correlation images. The results
presented employ methods which can be used in real-time to estimate the error
on centroids, allowing the system to use real data to optimize parameters,
without needing to enter a separate calibration mode. This method can also be
applied outside of solar AO to any field which requires the tracking of an
extended object.

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The categories of this paper are: mtrl-th
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The categories of this paper are: physics
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The categories of this paper are: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: math-ph
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat