lsst.meas.astrom gf1cff7945b+cac3717750
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Classes | Functions
lsst.meas.astrom.approximateWcs Namespace Reference

Classes

class  _MockTestCase
 

Functions

 approximateWcs (wcs, bbox, order=3, nx=20, ny=20, iterations=3, skyTolerance=0.001 *lsst.geom.arcseconds, pixelTolerance=0.02, useTanWcs=False)
 

Function Documentation

◆ approximateWcs()

lsst.meas.astrom.approximateWcs.approximateWcs (   wcs,
  bbox,
  order = 3,
  nx = 20,
  ny = 20,
  iterations = 3,
  skyTolerance = 0.001*lsst.geom.arcseconds,
  pixelTolerance = 0.02,
  useTanWcs = False 
)
Approximate an existing WCS as a TAN-SIP WCS

The fit is performed by evaluating the WCS at a uniform grid of points
within a bounding box.

Parameters
----------
wcs : `lsst.afw.geom.SkyWcs`
    wcs to approximate
bbox : `lsst.geom.Box2I`
    the region over which the WCS will be fit
order : `int`
    order of SIP fit
nx : `int`
    number of grid points along x
ny : `int`
    number of grid points along y
iterations : `int`
    number of times to iterate over fitting
skyTolerance : `lsst.geom.Angle`
    maximum allowed difference in world coordinates between
    input wcs and approximate wcs (default is 0.001 arcsec)
pixelTolerance : `float`
    maximum allowed difference in pixel coordinates between
    input wcs and approximate wcs (default is 0.02 pixels)
useTanWcs : `bool`
    send a TAN version of wcs to the fitter? It is documented to require that,
    but I don't think the fitter actually cares

Returns
-------
fitWcs : `lsst.afw.geom.SkyWcs`
    the fit TAN-SIP WCS

Definition at line 43 of file approximateWcs.py.