piffPsf.py

Go to the documentation of this file.

# This file is part of meas_extensions_piff.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (https://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
__all__ = ["PiffPsf"]
 
import pickle
import piff
from packaging.version import Version
import numpy as np
from lsst.afw.typehandling import StorableHelperFactory
from lsst.meas.algorithms import ImagePsf
from lsst.afw.image import Image
from lsst.geom import Box2I, Point2I, Extent2I, Point2D
 
 
class PiffPsf(ImagePsf):
    _factory = StorableHelperFactory(
        "lsst.meas.extensions.piff.piffPsf",
        "PiffPsf"
    )
 
    def __init__(self, width, height, piffResult):
        assert width == height
        ImagePsf.__init__(self)
        self.width = width
        self.height = height
        self.dimensions = Extent2I(width, height)
        self._piffResult = piffResult
        self._averagePosition = None
 
    @property
    def piffResult(self):
        return self._piffResult
 
    # Storable overrides
 
    def isPersistable(self):
        return True
 
    def _getPersistenceName(self):
        return "PiffPsf"
 
    def _getPythonModule(self):
        return "lsst.meas.extensions.piff.piffPsf"
 
    def _write(self):
        return pickle.dumps((self.width, self.height, self._piffResult))
 
    @staticmethod
    def _read(pkl):
        width, height, piffResult = pickle.loads(pkl)
        # We need to do surgery on pickles created with earlier versions of
        # piff when using piff version 1.4 or later.
        if Version(piff.version) >= Version("1.4"):
            if not hasattr(piffResult, "_num"):
                piffResult._num = None
                piffResult.model._num = None
                piffResult.model._fit_flux = None
                piffResult.interp._num = None
        return PiffPsf(width, height, piffResult)
 
    # ImagePsf overrides
 
    def __deepcopy__(self, meta=None):
        return PiffPsf(self.width, self.height, self._piffResult)
 
    def resized(self, width, height):
        assert width == height
        return PiffPsf(width, height, self._piffResult)
 
    def _doComputeImage(self, position, color):
        return self._doImage(position, center=None)
 
    def _doComputeKernelImage(self, position, color):
        return self._doImage(position, center=True)
 
    def _doComputeBBox(self, position, color):
        return self._doBBox(Point2I(0, 0), center=True)
 
    def getAveragePosition(self):
        if self._averagePosition is None:
            x = np.mean([star.image_pos.x for star in self._piffResult.stars])
            y = np.mean([star.image_pos.y for star in self._piffResult.stars])
            self._averagePosition = Point2D(x, y)
        return self._averagePosition
 
    # Internal private methods
 
    def _doImage(self, position, center):
        # Follow Piff conventions for center.
        # None => draw as if star at position
        # True => draw in center of image
        gsimg = self._piffResult.draw(
            position.x, position.y, stamp_size=self.width, center=center
        )
        bbox = self._doBBox(position, center)
        img = Image(bbox, dtype=np.float64)
        img.array[:] = gsimg.array
        img.array /= np.sum(img.array)
        return img
 
    def _doBBox(self, position, center):
        origin = -(self.dimensions//2)
        if center is None:
            origin = Point2I(position) + origin
        return Box2I(Point2I(origin), self.dimensions)