lsst.pipe.tasks g4a6547c0d5+6fab381471
mockObject.py
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6# LSST Project (http://www.lsst.org/).
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22import numpy
23
24import lsst.pex.config
25import lsst.afw.table
26import lsst.geom
27import lsst.afw.image
28import lsst.pipe.base
29
30
31class MockObjectConfig(lsst.pex.config.Config):
32 minMag = lsst.pex.config.Field(dtype=float, default=18.0, doc="Minimum magnitude for mock objects")
33 maxMag = lsst.pex.config.Field(dtype=float, default=20.0, doc="Maximum magnitude for mock objects")
34 maxRadius = lsst.pex.config.Field(
35 dtype=float, default=10.0,
36 doc=("Maximum radius of an object in arcseconds; only used "
37 "when determining which objects are in an exposure.")
38 )
39 spacing = lsst.pex.config.Field(
40 dtype=float, default=20.0,
41 doc="Distance between objects (in arcseconds)."
42 )
43 seed = lsst.pex.config.Field(dtype=int, default=1, doc="Seed for numpy random number generator")
44
45
46class MockObjectTask(lsst.pipe.base.Task):
47 """Task that generates simple mock objects and draws them on images, intended as a subtask of
48 MockCoaddTask.
49
50 May be subclassed to generate things other than stars.
51 """
52
53 ConfigClass = MockObjectConfig
54
55 def __init__(self, **kwds):
56 lsst.pipe.base.Task.__init__(self, **kwds)
58 self.center = lsst.afw.table.Point2DKey.addFields(self.schema, "center",
59 "center position in tract WCS", "pixel")
60 self.magKey = self.schema.addField("mag", type=float, doc="exact true magnitude")
61 self.rng = numpy.random.RandomState(self.config.seed)
62
63 def run(self, tractInfo, catalog=None):
64 """Add records to the truth catalog and return it, delegating to makePositions and defineObject.
65
66 If the given catalog is not None, add records to this catalog and return it instead
67 of creating a new one.
68
69 Subclasses should generally not need to override this method.
70 """
71 if catalog is None:
73 else:
74 if not catalog.getSchema().contains(self.schema):
75 raise ValueError("Catalog schema does not match Task schema")
76 for coord, center in self.makePositions(tractInfo):
77 record = catalog.addNew()
78 record.setCoord(coord)
79 record.set(self.center, center)
80 self.defineObject(record)
81 return catalog
82
83 def makePositions(self, tractInfo):
84 """Generate the centers (as a (coord, point) tuple) of mock objects (the point returned is
85 in the tract coordinate system).
86
87 Default implementation puts objects on a grid that is square in the tract's image coordinate
88 system, with spacing approximately given by config.spacings.
89
90 The return value is a Python iterable over (coord, point) pairs; the default implementation
91 is actually an iterator (i.e. the function is a "generator"), but derived-class overrides may
92 return any iterable.
93 """
94 wcs = tractInfo.getWcs()
95 spacing = self.config.spacing / wcs.getPixelScale().asArcseconds() # get spacing in tract pixels
96 bbox = tractInfo.getBBox()
97 for y in numpy.arange(bbox.getMinY() + 0.5 * spacing, bbox.getMaxY(), spacing):
98 for x in numpy.arange(bbox.getMinX() + 0.5 * spacing, bbox.getMaxX(), spacing):
99 yield wcs.pixelToSky(x, y), lsst.geom.Point2D(x, y),
100
101 def defineObject(self, record):
102 """Fill in additional fields in a truth catalog record (id and coord will already have
103 been set).
104 """
105 mag = self.rng.rand() * (self.config.maxMag - self.config.minMag) + self.config.minMag
106 record.setD(self.magKey, mag)
107
108 def drawSource(self, record, exposure, buffer=0):
109 """Draw the given truth catalog record on the given exposure, makings use of its Psf, Wcs,
110 PhotoCalib, and possibly filter to transform it appropriately.
111
112 The mask and variance planes of the Exposure are ignored.
113
114 The 'buffer' parameter is used to expand the source's bounding box when testing whether it
115 is considered fully part of the image.
116
117 Returns 0 if the object does not appear on the given image at all, 1 if it appears partially,
118 and 2 if it appears fully (including the given buffer).
119 """
120 wcs = exposure.getWcs()
121 center = wcs.skyToPixel(record.getCoord())
122 try:
123 psfImage = exposure.getPsf().computeImage(center).convertF()
124 except Exception:
125 return 0
126 psfBBox = psfImage.getBBox()
127 overlap = exposure.getBBox()
128 overlap.clip(psfBBox)
129 if overlap.isEmpty():
130 return 0
131 flux = exposure.getPhotoCalib().magnitudeToInstFlux(record.getD(self.magKey))
132 normalization = flux / psfImage.getArray().sum()
133 if psfBBox != overlap:
134 psfImage = psfImage.Factory(psfImage, overlap)
135 result = 1
136 else:
137 result = 2
138 if buffer != 0:
139 bufferedBBox = lsst.geom.Box2I(psfBBox)
140 bufferedBBox.grow(buffer)
141 bufferedOverlap = exposure.getBBox()
142 bufferedOverlap.clip(bufferedBBox)
143 if bufferedOverlap != bufferedBBox:
144 result = 1
145 image = exposure.getMaskedImage().getImage()
146 subImage = image.Factory(image, overlap)
147 subImage.scaledPlus(normalization, psfImage)
148 return result
static Schema makeMinimalSchema()
def drawSource(self, record, exposure, buffer=0)
Definition: mockObject.py:108
def run(self, tractInfo, catalog=None)
Definition: mockObject.py:63