lsst.skymap.tractInfo.TractInfo Class Reference

Inheritance diagram for lsst.skymap.tractInfo.TractInfo:

Public Member Functions
def	__init__
def	findPatch
def	findPatchList
def	getBBox
def	getCtrCoord
def	getId
def	getNumPatches
def	getPatchBorder
def	getPatchInfo
def	getPatchInnerDimensions
def	getTractOverlap
def	getVertexList
def	getWcs
def	__str__
def	__repr__
def	__iter__
def	__len__
def	__getitem__

Private Member Functions
def	_minimumBoundingBox
def	_setupPatches
def	_finalOrientation

Private Attributes
	_id
	_patchInnerDimensions
	_patchBorder
	_ctrCoord
	_vertexCoordList
	_tractOverlap
	_numPatches
	_wcs

Detailed Description

Information about a tract in a SkyMap sky pixelization

The tract is subdivided into rectangular patches. Each patch has the following properties:
- An inner region defined by an inner bounding. The inner regions of the patches exactly tile the tract,
  and all inner regions have the same dimensions. The tract is made larger as required to make this work.
- An outer region defined by an outer bounding box. The outer region extends beyond the inner region
  by patchBorder pixels in all directions, except there is no border at the edges of the tract.
  Thus patches overlap each other but never extend off the tract. If you do not want any overlap
  between adjacent patches then set patchBorder to 0.
- An index that consists of a pair of integers:
    0 <= x index < numPatches[0]
    0 <= y index < numPatches[1]
  Patch 0,0 is at the minimum corner of the tract bounding box.

Definition at line 30 of file tractInfo.py.

Constructor & Destructor Documentation

def lsst.skymap.tractInfo.TractInfo.__init__	(		self,
			id,
			patchInnerDimensions,
			patchBorder,
			ctrCoord,
			vertexCoordList,
			tractOverlap,
			wcs
	)

Construct a TractInfo

@param[in] id: tract ID
@param[in] patchInnerDimensions: dimensions of inner region of patches (x,y pixels)
@param[in] patchBorder: overlap between adjacent patches (in pixels, one int)
@param[in] ctrCoord: sky coordinate of center of inner region of tract, as an afwCoord.Coord;
    also used as the CRVAL for the WCS.
@param[in] vertexCoordList: list of sky coordinates (afwCoord.Coord)
    of vertices that define the boundaries of the inner region
@param[in] tractOverlap: minimum overlap between adjacent sky tracts; an afwGeom.Angle;
    this defines the minimum distance the tract extends beyond the inner region in all directions
@param[in,out] wcs: an afwImage.Wcs; the reference pixel will be shifted as required
    so that the lower left-hand pixel (index 0,0) has pixel position 0.0, 0.0

@warning
- It is not enforced that ctrCoord is the center of vertexCoordList, but SkyMap relies on it
- vertexCoordList will likely become a geom SphericalConvexPolygon someday.

Definition at line 45 of file tractInfo.py.

    def __init__(self, id, patchInnerDimensions, patchBorder, ctrCoord, vertexCoordList, tractOverlap, wcs):
        """Construct a TractInfo

        @param[in] id: tract ID
        @param[in] patchInnerDimensions: dimensions of inner region of patches (x,y pixels)
        @param[in] patchBorder: overlap between adjacent patches (in pixels, one int)
        @param[in] ctrCoord: sky coordinate of center of inner region of tract, as an afwCoord.Coord;
            also used as the CRVAL for the WCS.
        @param[in] vertexCoordList: list of sky coordinates (afwCoord.Coord)
            of vertices that define the boundaries of the inner region
        @param[in] tractOverlap: minimum overlap between adjacent sky tracts; an afwGeom.Angle;
            this defines the minimum distance the tract extends beyond the inner region in all directions
        @param[in,out] wcs: an afwImage.Wcs; the reference pixel will be shifted as required
            so that the lower left-hand pixel (index 0,0) has pixel position 0.0, 0.0
        
        @warning
        - It is not enforced that ctrCoord is the center of vertexCoordList, but SkyMap relies on it
        - vertexCoordList will likely become a geom SphericalConvexPolygon someday.
        """
        self._id = id
        try:
            assert len(patchInnerDimensions) == 2
            self._patchInnerDimensions = afwGeom.Extent2I(*(int(val) for val in patchInnerDimensions))
        except:
            raise TypeError("patchInnerDimensions=%s; must be two ints" % (patchInnerDimensions,))
        self._patchBorder = int(patchBorder)
        self._ctrCoord = ctrCoord
        self._vertexCoordList = tuple(coord.clone() for coord in vertexCoordList)
        self._tractOverlap = tractOverlap
        
        minBBox = self._minimumBoundingBox(wcs)
        initialBBox, self._numPatches = self._setupPatches(minBBox, wcs)
        self._bbox, self._wcs = self._finalOrientation(initialBBox, wcs)