TractInfo¶
-
class
lsst.skymap.
TractInfo
(id, patchInnerDimensions, patchBorder, ctrCoord, vertexCoordList, tractOverlap, wcs)¶ Bases:
object
Information about a tract in a SkyMap sky pixelization
Parameters: - id :
int
tract ID
- patchInnerDimensions :
tuple
ofint
Dimensions of inner region of patches (x,y pixels).
- patchBorder :
int
Overlap between adjacent patches (in pixels)
- ctrCoord :
lsst.geom.SpherePoint
ICRS sky coordinate of center of inner region of tract; also used as the CRVAL for the WCS.
- vertexCoordList :
list
oflsst.geom.SpherePoint
Vertices that define the boundaries of the inner region.
- tractOverlap :
lsst.geom.Angle
Minimum overlap between adjacent sky tracts; this defines the minimum distance the tract extends beyond the inner region in all directions.
- wcs :
lsst.afw.image.SkyWcs
WCS for tract. 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.
Notes
The tract is subdivided into rectangular patches. Each patch has the following properties:
An inner region defined by an inner bounding box. 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.
It is not enforced that ctrCoord is the center of vertexCoordList, but SkyMap relies on it.
Methods Summary
contains
(coord)Does this tract contain the coordinate? findPatch
(coord)Find the patch containing the specified coord. findPatchList
(coordList)Find patches containing the specified list of coords. getBBox
()Get bounding box of tract (as an geom.Box2I) getCtrCoord
()Get ICRS sky coordinate of center of tract (as an lsst.geom.SpherePoint) getId
()Get ID of tract getInnerSkyPolygon
()Get inner on-sky region as a sphgeom.ConvexPolygon. getNumPatches
()Get the number of patches in x, y. getOuterSkyPolygon
()Get outer on-sky region as a sphgeom.ConvexPolygon getPatchBorder
()getPatchIndexPair
(sequentialIndex)getPatchInfo
(index)Return information for the specified patch. getPatchInnerDimensions
()Get dimensions of inner region of the patches (all are the same) getSequentialPatchIndex
(patchInfo)Return a single integer that uniquely identifies the given patch within this tract. getTractOverlap
()Get minimum overlap of adjacent sky tracts. getVertexList
()Get list of ICRS sky coordinates of vertices that define the boundary of the inner region. getWcs
()Get WCS of tract. Methods Documentation
-
contains
(coord)¶ Does this tract contain the coordinate?
-
findPatch
(coord)¶ Find the patch containing the specified coord.
Parameters: - coord :
lsst.geom.SpherePoint
ICRS sky coordinate to search for.
Returns: - result :
lsst.skymap.PatchInfo
PatchInfo of patch whose inner bbox contains the specified coord
Raises: - LookupError
If coord is not in tract or we cannot determine the pixel coordinate (which likely means the coord is off the tract).
- coord :
-
findPatchList
(coordList)¶ Find patches containing the specified list of coords.
Parameters: - coordList :
list
oflsst.geom.SpherePoint
ICRS sky coordinates to search for.
Returns: - result :
list
oflsst.skymap.PatchInfo
List of PatchInfo for patches that contain, or may contain, the specified region. The list will be empty if there is no overlap.
Notes
Warning:
- This may give incorrect answers on regions that are larger than a tract.
- This uses a naive algorithm that may find some patches that do not overlap the region (especially if the region is not a rectangle aligned along patch x,y).
- coordList :
-
getBBox
()¶ Get bounding box of tract (as an geom.Box2I)
-
getCtrCoord
()¶ Get ICRS sky coordinate of center of tract (as an lsst.geom.SpherePoint)
-
getId
()¶ Get ID of tract
-
getInnerSkyPolygon
()¶ Get inner on-sky region as a sphgeom.ConvexPolygon.
-
getNumPatches
()¶ Get the number of patches in x, y.
Returns:
-
getOuterSkyPolygon
()¶ Get outer on-sky region as a sphgeom.ConvexPolygon
-
getPatchBorder
()¶
-
getPatchIndexPair
(sequentialIndex)¶
-
getPatchInfo
(index)¶ Return information for the specified patch.
Parameters: Returns: - result :
lsst.skymap.PatchInfo
The patch info for that index.
Raises: - IndexError
If index is out of range.
- result :
-
getPatchInnerDimensions
()¶ Get dimensions of inner region of the patches (all are the same)
-
getSequentialPatchIndex
(patchInfo)¶ Return a single integer that uniquely identifies the given patch within this tract.
-
getTractOverlap
()¶ Get minimum overlap of adjacent sky tracts.
-
getVertexList
()¶ Get list of ICRS sky coordinates of vertices that define the boundary of the inner region.
Notes
warning: this is not a deep copy.
-
getWcs
()¶ Get WCS of tract.
Returns: - wcs :
lsst.afw.geom.SkyWcs
The WCS of this tract
- wcs :
- id :