Package pydrizzle :: Module obsgeometry :: Class GeometryModel

Class GeometryModel

Base class for Distortion model. There will be a separate class for each type of model/filetype used with drizzle, i.e., IDCModel and DrizzleModel.

Each class will know how to apply the distortion to a single point and how to convert coefficients to an input table suitable for the drizzle task.

Coefficients will be stored in CX,CY arrays.

Instance Methods

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__init__(self)
This will open the given file and determine its type and norder.

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shift(self, cx, cy, xs, ys)
Shift reference position of coefficients to new center where (xs,ys) = old-reference-position - subarray/image center.

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convert(self, tmpname, xref=None, yref=None, delta=yes)
Open up an ASCII file, output coefficients in drizzle format after converting them as necessary.

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apply(self, pixpos, scale=1.0, order=None)
Apply coefficients to a pixel position or a list of positions.

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setPScaleCoeffs(self, pscale)

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Class Variables

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NORDER = 3

Method Details

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shift(self, cx, cy, xs, ys)

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Shift reference position of coefficients to new center where (xs,ys) = old-reference-position - subarray/image center. This will support creating coeffs files for drizzle which will be applied relative to the center of the image, rather than relative to the reference position of the chip.

convert(self, tmpname, xref=None, yref=None, delta=yes)

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 Open up an ASCII file, output coefficients in drizzle
  format after converting them as necessary.
First, normalize these coefficients to what drizzle expects
Normalize the coefficients by the MODEL/output plate scale.

16-May-2002:
Revised to work with higher order polynomials by John Blakeslee.
27-June-2002:
    Added ability to shift coefficients to new center for support
        of subarrays.

apply(self, pixpos, scale=1.0, order=None)

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 Apply coefficients to a pixel position or a list of positions.
  This should be the same for all coefficients tables.
Return the geometrically-adjusted position
in arcseconds from the reference position as a tuple (x,y).

Compute delta from reference position