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Diffstat (limited to 'lib/skyline.py')
| -rw-r--r-- | lib/skyline.py | 173 |
1 files changed, 144 insertions, 29 deletions
diff --git a/lib/skyline.py b/lib/skyline.py index 05fd279..a8e27a2 100644 --- a/lib/skyline.py +++ b/lib/skyline.py @@ -1,48 +1,163 @@ +"""Manage outlines on the sky. + +This module provides support for working with footprints +on the sky. Primary use case would use the following +generalized steps:: + + #. Initialize SkyLine objects for each input image. + This object would be the union of all the input + image's individual chips WCS footprints. + + #. Determine overlap between all images. The + determination would employ a recursive operation + to return the extended list of all overlap values + computed as [img1 vs [img2,img3,...,imgN],img2 vs + [img3,...,imgN],...] + + #. Select the pair with the largest overlap, or the + pair which produces the largest overlap with the + first input image. This defines the initial + reference SkyLine object. + + #. Perform some operation on the 2 images: for example, + match sky in intersecting regions, or aligning + second image with the first (reference) image. + + #. Update the second image, either apply the sky value + or correct the WCS, then generate a new SkyLine + object for that image. + + #. Create a new reference SkyLine object as the union + of the initial reference object and the newly + updated SkyLine object. + + #. Repeat Steps 2-6 for all remaining input images. + +This process will work reasonably fast as most operations +are performed using the SkyLine objects and WCS information +solely, not image data itself. + +.. note:: Requires Python 2.7 or later. + +:Authors: Pey Lian Lim, W. Hack + +:Organization: Space Telescope Science Institute + +:History: + * 2012-05-25 PLL updated doc. Original class structure by WJH. + +Examples +-------- +>>> from sphere import SkyLine + """ -skyline -- Manage outlines on the sky - -This module provides support for working with footprints on the sky. -Primary use case would use the following generalized steps:: - -1. Initialize SkyLine objects for each input image. This object would be the - union of all the input image's individual chips WCS footprints. -2. Determine overlap between all images. The determination would employ a - recursive operation to return the extended list of all overlap values - computed as [img1 vs [img2,img3,...,imgN],img2 vs [img3,...,imgN],...] -3. Select the pair with the largest overlap, or the pair which produces the - largest overlap with the first input image. This defines the initial - reference SkyLine object. -4. Perform some operation on the 2 images: for example, match sky in intersecting - regions, or aligning second image with the first (reference) image. -5. Update the second image, either apply the sky value or correct the WCS, then - generate a new SkyLine object for that image. -6. Create a new reference SkyLine object as the union of the initial reference - object and the newly updated SkyLine object. -7. Repeat Steps 2-6 for all remaining input images. - -This process will work reasonably fast as most operations are performed using -the SkyLine objects and WCS information solely, not image data itself. -""" +from __future__ import division, print_function + +# THIRD-PARTY import pyfits +from stwcs import wcsutil -import sphere +# LOCAL +from polygon import SphericalPolygon -class SkyLine(object): - def __init__(self,fname): - pass +__all__ = ['SkyLine'] + +class SkyLine(SphericalPolygon): + + def __init__(self, fname): + """Initialize SkyLine object instance. + + Parameters + ---------- + self: obj + SkyLine instance. + + fname: str + FITS image. + + """ + # Find SCI extensions + with pyfits.open(fname) as pf: + sci_extnum = tuple([i for i,ext in enumerate(pf) if + 'SCI' in ext.name.upper()]) + assert len(sci_extnum) > 0, \ + 'SkyLine cannot find SCI ext in {}.'.format(fname) + + # Initialize mosaic with first chip + all_sph = SphericalPolygon.from_wcs( + wcsutil.HSTWCS(fname, ext=sci_extnum[0])) + + # Mosaic all the chips + for i in sci_extnum[1:]: + prev_sph = all_sph.__copy__() + + cur_sph = SphericalPolygon.from_wcs( + wcsutil.HSTWCS(fname, ext=i)) + + all_sph = prev_sph.union(cur_sph) + + # SkyLine = final mosaic inheriting from SphericalPolygon + SphericalPolygon.__init__(self, all_sph.points, all_sph.inside) + + # Add attribute to track images in SkyLine + self._image_list = [fname] + + @property + def image_list(self): + """List of images in SkyLine.""" + return self._image_list + +# Overload parent class with following changes +# a. add own attr +# b. update self var in-place, no return def add_image(self,skyline): + """Make composite SkyLine""" pass def compute_overlap(self, skyline): + """Return sphere object with intersect of 2 skylines. + + Wrapper of sphere overlap method. + + """ pass def find_intersection(self, skyline): + """ + Return WCS object of overlap of 2 skylines. + + """ pass def within(self, pos): + """ + Return bool if pos is in skyline or not. + + """ pass def create_wcs(self): + """Create WCS from SkyLine object. + + .. note:: Use stwcs to define a plane using multiple HSTWCS object + + Returns + ------- + wcs: obj + New HSTWCS objects. + + """ pass - + + def footprints(self): + """Compute edges of skyline.""" + pass + + +def test(): + """Basic use case.""" + + # Allow disjoint? + + pass |