LSSTApplications  18.0.0+53,19.0.0,19.0.0+1,19.0.0+15,19.0.0+16,19.0.0+18,19.0.0+23,19.0.0+3,19.0.0-1-g20d9b18+9,19.0.0-1-g425ff20,19.0.0-1-g5549ca4,19.0.0-1-g580fafe+9,19.0.0-1-g6fe20d0+2,19.0.0-1-g8c57eb9+9,19.0.0-1-gbfe0924,19.0.0-1-gdc0e4a7+14,19.0.0-1-ge272bc4+9,19.0.0-1-ge3aa853+1,19.0.0-14-gbb28fe44,19.0.0-16-g8258e2a,19.0.0-2-g0d9f9cd+16,19.0.0-2-g260436e,19.0.0-2-g9b11441+3,19.0.0-2-gd955cfd+22,19.0.0-3-g6513920,19.0.0-3-gc4f6e04,19.0.0-4-g41ffa1d+2,19.0.0-4-g725f80e+18,19.0.0-4-g75300c1e,19.0.0-4-ga8eba22,19.0.0-5-g0745e3f,19.0.0-6-g6637c4fb6,19.0.0-6-gb6b8b0a,19.0.0-7-gea0a0fe+5,w.2020.03
LSSTDataManagementBasePackage
Functions
lsst.meas.astrom.verifyWcs Namespace Reference

Functions

def checkMatches (srcMatchSet, exposure, log=None)
 

Function Documentation

◆ checkMatches()

def lsst.meas.astrom.verifyWcs.checkMatches (   srcMatchSet,
  exposure,
  log = None 
)
Check astrometric matches and assess Wcs quality by computing statics
over spacial cells in the image.

Parameters
----------
srcMatchSet : `list` of `lsst.afw.table.ReferenceMatch`
    List of matched sources to a reference catalog.
exposure : `lsst.afw.image.Exposure`
    Image the sources in srcMatchSet were detected/measured in.
log : `lsst.log.Log`
    Logger object.

Returns
-------
values : `dict`
    Result dictionary with fields:

    - ``minObjectsPerCell`` : (`int`)
    - ``maxObjectsPerCell`` : (`int`)
    - ``meanObjectsPerCell`` : (`float`)
    - ``stdObjectsPerCell`` : (`float`)

Definition at line 35 of file verifyWcs.py.

35 def checkMatches(srcMatchSet, exposure, log=None):
36  """Check astrometric matches and assess Wcs quality by computing statics
37  over spacial cells in the image.
38 
39  Parameters
40  ----------
41  srcMatchSet : `list` of `lsst.afw.table.ReferenceMatch`
42  List of matched sources to a reference catalog.
43  exposure : `lsst.afw.image.Exposure`
44  Image the sources in srcMatchSet were detected/measured in.
45  log : `lsst.log.Log`
46  Logger object.
47 
48  Returns
49  -------
50  values : `dict`
51  Result dictionary with fields:
52 
53  - ``minObjectsPerCell`` : (`int`)
54  - ``maxObjectsPerCell`` : (`int`)
55  - ``meanObjectsPerCell`` : (`float`)
56  - ``stdObjectsPerCell`` : (`float`)
57  """
58  if not exposure:
59  return {}
60 
61  if log is None:
62  log = Log.getLogger("meas.astrom.verifyWcs.checkMatches")
63 
64  im = exposure.getMaskedImage().getImage()
65  width, height = im.getWidth(), im.getHeight()
66  nx, ny = 3, 3
67  w, h = width//nx, height//ny
68 
69  if w == 0:
70  w = 1
71  while nx*w < width:
72  w += 1
73 
74  if h == 0:
75  h = 1
76  while ny*h < height:
77  h += 1
78 
79  cellSet = afwMath.SpatialCellSet(
80  lsst.geom.Box2I(lsst.geom.Point2I(0, 0), lsst.geom.Extent2I(width, height)), w, h)
81  #
82  # Populate cellSet
83  #
84  i = -1
85  for m in srcMatchSet:
86  i += 1
87 
88  src = m.second
89  csrc = afwDetection.Source()
90  csrc.setId(i)
91  csrc.setXAstrom(src.getXAstrom())
92  csrc.setYAstrom(src.getYAstrom())
93 
94  try:
95  cellSet.insertCandidate(measAlg.PsfCandidateF(csrc, exposure.getMaskedImage()))
96  except Exception as e:
97  log.warn(str(e))
98 
99  ncell = len(cellSet.getCellList())
100  nobj = np.ndarray(ncell, dtype='i')
101 
102  for i in range(ncell):
103  cell = cellSet.getCellList()[i]
104 
105  nobj[i] = cell.size()
106 
107  dx = np.ndarray(cell.size())
108  dy = np.ndarray(cell.size())
109 
110  j = 0
111  for cand in cell:
112  #
113  # Swig doesn't know that we're a SpatialCellImageCandidate; all it knows is that we have
114  # a SpatialCellCandidate so we need an explicit (dynamic) cast
115  #
116  mid = cand.getSource().getId()
117  dx[j] = srcMatchSet[mid].first.getXAstrom() - srcMatchSet[mid].second.getXAstrom()
118  dy[j] = srcMatchSet[mid].first.getYAstrom() - srcMatchSet[mid].second.getYAstrom()
119 
120  j += 1
121 
122  log.debug("%s %-30s %8s dx,dy = %5.2f,%5.2f rms_x,y = %5.2f,%5.2f",
123  cell.getLabel(), cell.getBBox(), ("nobj=%d" % cell.size()),
124  dx.mean(), dy.mean(), dx.std(), dy.std())
125 
126  nobj.sort()
127 
128  values = {}
129  values["minObjectsPerCell"] = int(nobj[0]) # otherwise it's a numpy integral type
130  values["maxObjectsPerCell"] = int(nobj[-1])
131  values["meanObjectsPerCell"] = nobj.mean()
132  values["stdObjectsPerCell"] = nobj.std()
133 
134  return values
135 
A collection of SpatialCells covering an entire image.
Definition: SpatialCell.h:387
def checkMatches(srcMatchSet, exposure, log=None)
Definition: verifyWcs.py:35
An integer coordinate rectangle.
Definition: Box.h:55