def fit_island_iteratively(self, img, isl, iter_ngmax=5, opts=None):
"""Fits an island iteratively.
For large islands, which can require many Gaussians to fit well,
it is much faster to fit a small number of Gaussians simultaneously
and iterate. However, this does usually result in larger residuals.
"""
import functions as func
sgaul = []; sfgaul = []
gaul = []; fgaul = []
if opts == None:
opts = img.opts
thresh_isl = opts.thresh_isl
thresh_pix = opts.thresh_pix
thresh = opts.fittedimage_clip
thr = isl.mean + thresh_isl * isl.rms
rms = isl.rms
if opts.verbose_fitting:
print 'Iteratively fitting island ', isl.island_id
gaul = []; fgaul = []
ffimg_tot = N.zeros(isl.shape, dtype=N.float32)
peak_val = N.max(isl.image - isl.islmean)
while peak_val >= thr:
sgaul, sfgaul = self.fit_island(isl, opts, img, ffimg=ffimg_tot, ngmax=iter_ngmax, ini_gausfit='simple')
gaul = gaul + sgaul; fgaul = fgaul + sfgaul
# Calculate residual image
if len(sgaul) > 0:
for g in sgaul:
gcopy = g[:]
gcopy[1] -= isl.origin[0]
gcopy[2] -= isl.origin[1]
S1, S2, Th = func.corrected_size(gcopy[3:6])
gcopy[3] = S1
gcopy[4] = S2
gcopy[5] = Th
A, C1, C2, S1, S2, Th = gcopy
shape = isl.shape
b = find_bbox(thresh*isl.rms, gcopy)
bbox = N.s_[max(0, int(C1-b)):min(shape[0], int(C1+b+1)),
max(0, int(C2-b)):min(shape[1], int(C2+b+1))]
x_ax, y_ax = N.mgrid[bbox]
ffimg = func.gaussian_fcn(gcopy, x_ax, y_ax)
ffimg_tot[bbox] += ffimg
peak_val_prev = peak_val
peak_val = N.max(isl.image - isl.islmean - ffimg_tot)
if func.approx_equal(peak_val, peak_val_prev):
break
else:
break
if len(gaul) == 0:
# Fitting iteratively did not work -- try normal fit
gaul, fgaul = self.fit_island(isl, opts, img, ini_gausfit='default')
return gaul, fgaul
def __init__(self, img, gaussian, isl_idx, g_idx, flag=0):
"""Initialize Gaussian object from fitting data
Parameters:
img: PyBDSM image object
gaussian: 6-tuple of fitted numbers
isl_idx: island serial number
g_idx: gaussian serial number
flag: flagging (if any)
"""
import functions as func
from const import fwsig
import numpy as N
use_wcs = True
self.gaussian_idx = g_idx
self.gaus_num = 0 # stored later
self.island_id = isl_idx
self.jlevel = img.j
self.flag = flag
self.parameters = gaussian
p = gaussian
self.peak_flux = p[0]
self.centre_pix = p[1:3]
size = p[3:6]
if func.approx_equal(size[0], img.pixel_beam()[0]*1.1) and \
func.approx_equal(size[1], img.pixel_beam()[1]) and \
func.approx_equal(size[2], img.pixel_beam()[2]+90.0) or \
img.opts.fix_to_beam:
# Check whether fitted Gaussian is just the distorted pixel beam
# given as an initial guess or if size was fixed to the beam. If so,
# reset the size to the undistorted beam.
# Note: these are sigma sizes, not FWHM sizes.
size = img.pixel_beam()
size = (size[0], size[1], size[2]+90.0) # adjust angle so that corrected_size() works correctly
size = func.corrected_size(size) # gives fwhm and P.A.
self.size_pix = size # FWHM in pixels and P.A. CCW from +y axis
# Use img.orig_beam for flux calculation and deconvolution on wavelet
# images, as img.beam has been altered to match the wavelet scale.
# Note: these are all FWHM sizes.
if img.waveletimage:
bm_pix = N.array(img.beam2pix(img.orig_beam))
else:
bm_pix = N.array(img.beam2pix(img.beam))
# Calculate fluxes, sky sizes, etc. All sizes are FWHM.
tot = p[0]*size[0]*size[1]/(bm_pix[0]*bm_pix[1])
if flag == 0:
# These are good Gaussians
errors = func.get_errors(img, p+[tot], img.islands[isl_idx].rms)
self.centre_sky = img.pix2sky(p[1:3])
self.centre_skyE = img.pix2coord(errors[1:3], self.centre_pix, use_wcs=use_wcs)
self.size_sky = img.pix2gaus(size, self.centre_pix, use_wcs=use_wcs) # FWHM in degrees and P.A. east from north
self.size_sky_uncorr = img.pix2gaus(size, self.centre_pix, use_wcs=False) # FWHM in degrees and P.A. east from +y axis
self.size_skyE = img.pix2gaus(errors[3:6], self.centre_pix, use_wcs=use_wcs)
self.size_skyE_uncorr = img.pix2gaus(errors[3:6], self.centre_pix, use_wcs=False)
gaus_dc, err = func.deconv2(bm_pix, size)
self.deconv_size_sky = img.pix2gaus(gaus_dc, self.centre_pix, use_wcs=use_wcs)
self.deconv_size_sky_uncorr = img.pix2gaus(gaus_dc, self.centre_pix, use_wcs=False)
self.deconv_size_skyE = img.pix2gaus(errors[3:6], self.centre_pix, use_wcs=use_wcs)
self.deconv_size_skyE_uncorr = img.pix2gaus(errors[3:6], self.centre_pix, use_wcs=False)
else:
# These are flagged Gaussians, so don't calculate sky values or errors
errors = [0]*7
self.centre_sky = [0., 0.]
self.centre_skyE = [0., 0.]
self.size_sky = [0., 0., 0.]
self.size_sky_uncorr = [0., 0., 0.]
self.size_skyE = [0., 0.]
self.size_skyE_uncorr = [0., 0., 0.]
self.deconv_size_sky = [0., 0., 0.]
self.deconv_size_sky_uncorr = [0., 0., 0.]
self.deconv_size_skyE = [0., 0., 0.]
self.deconv_size_skyE_uncorr = [0., 0., 0.]
self.total_flux = tot
self.total_fluxE = errors[6]
self.peak_fluxE = errors[0]
self.total_fluxE = errors[6]
self.centre_pixE = errors[1:3]
self.size_pixE = errors[3:6]
self.rms = img.islands[isl_idx].rms
self.mean = img.islands[isl_idx].mean
self.total_flux_isl = img.islands[isl_idx].total_flux
self.total_flux_islE = img.islands[isl_idx].total_fluxE
