24 from .patchInfo
import PatchInfo
26 __all__ = [
"TractInfo"]
30 """Information about a tract in a SkyMap sky pixelization 32 The tract is subdivided into rectangular patches. Each patch has the following properties: 33 - An inner region defined by an inner bounding. The inner regions of the patches exactly tile the tract, 34 and all inner regions have the same dimensions. The tract is made larger as required to make this work. 35 - An outer region defined by an outer bounding box. The outer region extends beyond the inner region 36 by patchBorder pixels in all directions, except there is no border at the edges of the tract. 37 Thus patches overlap each other but never extend off the tract. If you do not want any overlap 38 between adjacent patches then set patchBorder to 0. 39 - An index that consists of a pair of integers: 40 0 <= x index < numPatches[0] 41 0 <= y index < numPatches[1] 42 Patch 0,0 is at the minimum corner of the tract bounding box. 45 def __init__(self, id, patchInnerDimensions, patchBorder, ctrCoord, vertexCoordList, tractOverlap, wcs):
46 """Construct a TractInfo 48 @param[in] id: tract ID 49 @param[in] patchInnerDimensions: dimensions of inner region of patches (x,y pixels) 50 @param[in] patchBorder: overlap between adjacent patches (in pixels, one int) 51 @param[in] ctrCoord: ICRS sky coordinate of center of inner region of tract 52 as an lsst.afw.geom.SpherePoint; also used as the CRVAL for the WCS. 53 @param[in] vertexCoordList: list of ICRS sky coordinates (lsst.afw.geom.SpherePoint) 54 of vertices that define the boundaries of the inner region 55 @param[in] tractOverlap: minimum overlap between adjacent sky tracts; an afwGeom.Angle; 56 this defines the minimum distance the tract extends beyond the inner region in all directions 57 @param[in,out] wcs: an afwImage.Wcs; the reference pixel will be shifted as required 58 so that the lower left-hand pixel (index 0,0) has pixel position 0.0, 0.0 61 - It is not enforced that ctrCoord is the center of vertexCoordList, but SkyMap relies on it 62 - vertexCoordList will likely become a geom SphericalConvexPolygon someday. 66 assert len(patchInnerDimensions) == 2
69 raise TypeError(
"patchInnerDimensions=%s; must be two ints" % (patchInnerDimensions,))
79 def _minimumBoundingBox(self, wcs):
80 """Calculate the minimum bounding box for the tract, given the WCS 82 The bounding box is created in the frame of the supplied WCS, 83 so that it's OK if the coordinates are negative. 85 We compute the bounding box that holds all the vertices and the 88 minBBoxD = afwGeom.Box2D()
92 minBBoxD.include(wcs.skyToPixel(vertexCoord))
95 angleIncr = afwGeom.Angle(360.0, afwGeom.degrees) / float(numAngles)
96 for i
in range(numAngles):
97 offAngle = angleIncr * i
98 offCoord = vertexCoord.offset(offAngle, halfOverlap)
99 pixPos = wcs.skyToPixel(offCoord)
100 minBBoxD.include(pixPos)
103 def _setupPatches(self, minBBox, wcs):
104 """Setup for patches of a particular size. 106 We grow the bounding box to hold an exact multiple of 107 the desired size (patchInnerDimensions), while keeping 108 the center roughly the same. We return the final 109 bounding box, and the number of patches in each dimension 112 @param minBBox Minimum bounding box for tract 113 @param wcs Wcs object 114 @return final bounding box, number of patches 116 bbox = afwGeom.Box2I(minBBox)
117 bboxMin = bbox.getMin()
118 bboxDim = bbox.getDimensions()
119 numPatches = afwGeom.Extent2I(0, 0)
121 num = (bboxDim[i] + innerDim - 1) // innerDim
122 deltaDim = (innerDim * num) - bboxDim[i]
124 bboxDim[i] = innerDim * num
125 bboxMin[i] -= deltaDim // 2
127 bbox = afwGeom.Box2I(bboxMin, bboxDim)
128 return bbox, numPatches
130 def _finalOrientation(self, bbox, wcs):
131 """Determine the final orientation 133 We offset everything so the lower-left corner is at 0,0 134 and compute the final Wcs. 136 @param bbox Current bounding box 137 @param wcs Current Wcs 138 @return revised bounding box, revised Wcs 140 finalBBox = afwGeom.Box2I(afwGeom.Point2I(0, 0), bbox.getDimensions())
143 pixPosOffset = afwGeom.Extent2D(finalBBox.getMinX() - bbox.getMinX(),
144 finalBBox.getMinY() - bbox.getMinY())
145 wcs = wcs.copyAtShiftedPixelOrigin(pixPosOffset)
146 return finalBBox, wcs
149 """Find the patch containing the specified coord 151 @param[in] coord: ICRS sky coordinate (lsst.afw.geom.SpherePoint) 152 @return PatchInfo of patch whose inner bbox contains the specified coord 154 @raise LookupError if coord is not in tract or we cannot determine the 155 pixel coordinate (which likely means the coord is off the tract). 157 @note This routine will be more efficient if coord is ICRS. 160 pixel = self.
getWcs().skyToPixel(coord)
163 raise LookupError(
"Unable to determine pixel position for coordinate %s" % (coord,))
164 pixelInd = afwGeom.Point2I(pixel)
166 raise LookupError(
"coord %s is not in tract %s" % (coord, self.
getId()))
171 """Find patches containing the specified list of coords 173 @param[in] coordList: list of sky coordinates (lsst.afw.geom.SpherePoint) 174 @return list of PatchInfo for patches that contain, or may contain, the specified region. 175 The list will be empty if there is no overlap. 178 * This may give incorrect answers on regions that are larger than a tract 179 * This uses a naive algorithm that may find some patches that do not overlap the region 180 (especially if the region is not a rectangle aligned along patch x,y). 182 box2D = afwGeom.Box2D()
183 for coord
in coordList:
185 pixelPos = self.
getWcs().skyToPixel(coord)
189 box2D.include(pixelPos)
190 bbox = afwGeom.Box2I(box2D)
199 for xInd
in range(llPatchInd[0], urPatchInd[0]+1)
200 for yInd
in range(llPatchInd[1], urPatchInd[1]+1))
203 """Get bounding box of tract (as an afwGeom.Box2I) 205 return afwGeom.Box2I(self._bbox)
208 """Get ICRS sky coordinate of center of tract (as an lsst.afw.geom.SpherePoint) 218 """Get the number of patches in x, y 220 @return the number of patches in x, y 227 @return patch border (pixels) 232 """Return information for the specified patch 234 @param[in] index: index of patch, as a pair of ints 235 @return patch info, an instance of PatchInfo 237 @raise IndexError if index is out of range 241 raise IndexError(
"Patch index %s is not in range [0-%d, 0-%d]" %
245 if not self._bbox.
contains(innerBBox):
247 "Bug: patch index %s valid but inner bbox=%s not contained in tract bbox=%s" %
248 (index, innerBBox, self._bbox))
249 outerBBox = afwGeom.Box2I(innerBBox)
251 outerBBox.clip(self._bbox)
259 """Get dimensions of inner region of the patches (all are the same) 261 @return dimensions of inner region of the patches (as an afwGeom Extent2I) 266 """Get minimum overlap of adjacent sky tracts 268 @return minimum overlap between adjacent sky tracts, as an afwGeom Angle 273 """Get list of sky coordinates of vertices that define the boundary of the inner region 275 @warning: this is not a deep copy 276 @warning vertexCoordList will likely become a geom SphericalConvexPolygon someday. 283 @warning: this is not a deep copy 288 return "TractInfo(id=%s)" % (self.
_id,)
291 return "TractInfo(id=%s, ctrCoord=%s)" % (self.
_id, self.
_ctrCoord.getVector())
295 for y
in range(yNum):
296 for x
in range(xNum):
307 """Does this tract contain the coordinate?""" 309 pixels = self.
getWcs().skyToPixel(coord)
317 """Information for a tract specified explicitly 319 A tract is placed at the explicitly defined coordinates, with the nominated 320 radius. The tracts are square (i.e., the radius is really a half-size). 323 def __init__(self, ident, patchInnerDimensions, patchBorder, ctrCoord, radius, tractOverlap, wcs):
327 super(ExplicitTractInfo, self).
__init__(ident, patchInnerDimensions, patchBorder, ctrCoord,
328 vertexList, tractOverlap, wcs)
330 bboxD = afwGeom.BoxD(self.
getBBox())
335 def _minimumBoundingBox(self, wcs):
336 """The minimum bounding box is calculated using the nominated radius""" 337 bbox = afwGeom.Box2D()
340 pixPos = wcs.skyToPixel(cornerCoord)
def getTractOverlap(self)
def _finalOrientation(self, bbox, wcs)
def _setupPatches(self, minBBox, wcs)
def getPatchInfo(self, index)
def contains(self, coord)
def getPatchInnerDimensions(self)
def __getitem__(self, index)
def _minimumBoundingBox(self, wcs)
def findPatch(self, coord)
def findPatchList(self, coordList)
def __init__(self, ident, patchInnerDimensions, patchBorder, ctrCoord, radius, tractOverlap, wcs)
def __init__(self, id, patchInnerDimensions, patchBorder, ctrCoord, vertexCoordList, tractOverlap, wcs)