Path: SpacecraftEstimation/StarCentroiding
% Finds the centroids given a pixelmap.
This uses the center of mass method. The centroids are calculated assuming a
lost-in-space condition. If the noise floor 'b' is empty, a noise floor will
be calculated from the pixelmap histogram. To calculate an edge noise instead
specify true for the edge flag.
x is defined in the column direction, y in the row direction.
iC is in the same units as the intensity of the pixel map.
With one output it will return [x0;y0;iC]
Type CoarseCentroids for a demo which will generate a small image using
ImagerPSF, add noise with PoissonNoise, calculate the centroids and plot the
results.
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Form:
options = CoarseCentroids;
[r0, iC, d] = CoarseCentroids( pixels, options, doPlot )
[x0] = CoarseCentroids( pixels, options, doPlot )
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Inputs
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pixels (:,:) Pixel map
options (.) Options data
.edge (1) Logical for computing edge noise
.blobify (1) Logical for using the Blobify algo
.T (1,1) Threshold indicating a star is present
.b (1,1) Sky-background noise floor
.nROI (1,1) Size of region of interest (pixels)
.minPix (1,1) Minimum number of pixels for valid star
doPlot (1,1) Specify true to generate the demo plots
-- Blobs if blobify was performed
-- Pixels above threshold
-- Pixelmap with centroids
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Outputs
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r0 (2,:) (x,y) centroid (column,row)
iC (1,:) Total intensity of the centroids
d (.) Algorithm data
.R (1,1) RMS of sky-background noise
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Reference: Liebe, C. "Accuracy Performance of Star Trackers - A Tutorial",
IEEE Transactions on Aerospace and Electronic Systems. Vol. 38, N0. 2,
April, 2002.
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See also FitHist, Blobify, CentroidCOM
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SpacecraftEstimation: StarCentroiding/Blobify SpacecraftEstimation: StarCentroiding/CentroidCOM SpacecraftEstimation: StarProcessing/ApplyThreshold SpacecraftEstimation: StarProcessing/FitHist SpacecraftEstimation: StarVisualization/DrawBlobs SpacecraftEstimation: StarVisualization/PlotCentroids Common: CommonData/SwooshWatermark Common: General/DeBlankLT Common: General/Watermark Common: Graphics/NewFig Common: Graphics/PltStyle Common: Graphics/XLabelS Common: Graphics/YLabelS Common: Graphics/ZLabelS Imaging: PSFUtils/ImagerPSF Imaging: PSFUtils/RHSGaussianPSF Imaging: Utilities/PoissonNoise Math: Linear/Mag
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