render_patch.py

from tractor import sdss as st
def tractor_render_patch(run, camcol, field, roi, celeste_src=None, bandname='r'):
    """ ROI = (x0, x1, y0, y1), zero indexed pixel coordinates """
    # set up tractor
    sdss   = DR9()
    getim  = st.get_tractor_image_dr9
    getsrc = st.get_tractor_sources_dr9
    imkw   = dict(zrange=[-3,100], sdss=sdss)

    # get images
    tim,tinf = getim(run, camcol, field, bandname, curl=True, roi=roi, **imkw)
    tim.zr = tinf['zr']

    # get corresponding sources
    sources = getsrc(run, camcol, field, bandname, bands=[bandname], curl=True, roi=roi)

    # set the first source to have the same parameters as dustin's
    if celeste_src is not None:
        print "setting source parameters"
        ts = sources[0]
        ts_pos = ts.getPosition()
        ts_pos.ra, ts_pos.dec = celeste_src.params.u

        from CelestePy.util.data import nanomaggies2mags
        band_mag = nanomaggies2mags(celeste_src.params.flux_dict[bandname])
        ts_bright = ts.getBrightness()
        ts_bright.setMag(bandname, band_mag)

    # create a tractor object, get a model image
    tractor = Tractor(images = [tim], catalog=[ts])
    mod     = tractor.getModelImage(tim, srcs=sources)
    chi     = tractor.getChiImage(imgi=0, srcs=sources)
    return mod, tim, chi