def createCandidate(self, threshold=0.1):
"""Create a PSF candidate from self.exp
@param threshold: Threshold for creating footprints on image
"""
source = self.catalog.addNew()
fpSet = afwDet.FootprintSet(self.exp.getMaskedImage(),
afwDet.Threshold(threshold), "DETECTED")
if display:
ds9.mtv(self.exp, frame=1)
for fp in fpSet.getFootprints():
for peak in fp.getPeaks():
ds9.dot("x", peak.getIx(), peak.getIy(), frame=1)
# There might be multiple footprints; only the one around self.x,self.y should go in the source
found = False
for fp in fpSet.getFootprints():
if fp.contains(afwGeom.Point2I(self.x, self.y)):
found = True
break
self.assertTrue(
found, "Unable to find central peak in footprint: faulty test")
source.setFootprint(fp)
return measAlg.PsfCandidateF(source, self.exp, self.x, self.y)
def 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`)
"""
if not exposure:
return {}
if log is None:
log = Log.getLogger("meas.astrom.verifyWcs.checkMatches")
im = exposure.getMaskedImage().getImage()
width, height = im.getWidth(), im.getHeight()
nx, ny = 3, 3
w, h = width // nx, height // ny
if w == 0:
w = 1
while nx * w < width:
w += 1
if h == 0:
h = 1
while ny * h < height:
h += 1
cellSet = afwMath.SpatialCellSet(
lsst.geom.Box2I(lsst.geom.Point2I(0, 0),
lsst.geom.Extent2I(width, height)), w, h)
#
# Populate cellSet
#
i = -1
for m in srcMatchSet:
i += 1
src = m.second
csrc = afwDetection.Source()
csrc.setId(i)
csrc.setXAstrom(src.getXAstrom())
csrc.setYAstrom(src.getYAstrom())
try:
cellSet.insertCandidate(
measAlg.PsfCandidateF(csrc, exposure.getMaskedImage()))
except Exception as e:
log.warn(str(e))
ncell = len(cellSet.getCellList())
nobj = np.ndarray(ncell, dtype='i')
for i in range(ncell):
cell = cellSet.getCellList()[i]
nobj[i] = cell.size()
dx = np.ndarray(cell.size())
dy = np.ndarray(cell.size())
j = 0
for cand in cell:
#
# Swig doesn't know that we're a SpatialCellImageCandidate; all it knows is that we have
# a SpatialCellCandidate so we need an explicit (dynamic) cast
#
mid = cand.getSource().getId()
dx[j] = srcMatchSet[mid].first.getXAstrom(
) - srcMatchSet[mid].second.getXAstrom()
dy[j] = srcMatchSet[mid].first.getYAstrom(
) - srcMatchSet[mid].second.getYAstrom()
j += 1
log.debug("%s %-30s %8s dx,dy = %5.2f,%5.2f rms_x,y = %5.2f,%5.2f",
cell.getLabel(), cell.getBBox(), ("nobj=%d" % cell.size()),
dx.mean(), dy.mean(), dx.std(), dy.std())
nobj.sort()
values = {}
values["minObjectsPerCell"] = int(
nobj[0]) # otherwise it's a numpy integral type
values["maxObjectsPerCell"] = int(nobj[-1])
values["meanObjectsPerCell"] = nobj.mean()
values["stdObjectsPerCell"] = nobj.std()
return values
def checkMatches(srcMatchSet, exposure, log=None):
if not exposure:
return {}
if log is None:
log = Log.getLogger("meas.astrom.verifyWcs.checkMatches")
im = exposure.getMaskedImage().getImage()
width, height = im.getWidth(), im.getHeight()
nx, ny = 3, 3
w, h = width // nx, height // ny
if w == 0:
w = 1
while nx * w < width:
w += 1
if h == 0:
h = 1
while ny * h < height:
h += 1
cellSet = afwMath.SpatialCellSet(
afwGeom.Box2I(afwGeom.Point2I(0, 0), afwGeom.Extent2I(width, height)),
w, h)
#
# Populate cellSet
#
i = -1
for m in srcMatchSet:
i += 1
src = m.second
csrc = afwDetection.Source()
csrc.setId(i)
csrc.setXAstrom(src.getXAstrom())
csrc.setYAstrom(src.getYAstrom())
try:
cellSet.insertCandidate(
measAlg.PsfCandidateF(csrc, exposure.getMaskedImage()))
except Exception as e:
log.warn(str(e))
ncell = len(cellSet.getCellList())
nobj = np.ndarray(ncell, dtype='i')
for i in range(ncell):
cell = cellSet.getCellList()[i]
nobj[i] = cell.size()
dx = np.ndarray(cell.size())
dy = np.ndarray(cell.size())
j = 0
for cand in cell:
#
# Swig doesn't know that we're a SpatialCellImageCandidate; all it knows is that we have
# a SpatialCellCandidate so we need an explicit (dynamic) cast
#
mid = cand.getSource().getId()
dx[j] = srcMatchSet[mid].first.getXAstrom(
) - srcMatchSet[mid].second.getXAstrom()
dy[j] = srcMatchSet[mid].first.getYAstrom(
) - srcMatchSet[mid].second.getYAstrom()
j += 1
log.debug("%s %-30s %8s dx,dy = %5.2f,%5.2f rms_x,y = %5.2f,%5.2f",
cell.getLabel(), cell.getBBox(), ("nobj=%d" % cell.size()),
dx.mean(), dy.mean(), dx.std(), dy.std())
nobj.sort()
values = {}
values["minObjectsPerCell"] = int(
nobj[0]) # otherwise it's a numpy integral type
values["maxObjectsPerCell"] = int(nobj[-1])
values["meanObjectsPerCell"] = nobj.mean()
values["stdObjectsPerCell"] = nobj.std()
return values