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1# This file is part of obs_base. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (https://www.lsst.org). 

6# See the COPYRIGHT file at the top-level directory of this distribution 

7# for details of code ownership. 

8# 

9# This program is free software: you can redistribute it and/or modify 

10# it under the terms of the GNU General Public License as published by 

11# the Free Software Foundation, either version 3 of the License, or 

12# (at your option) any later version. 

13# 

14# This program is distributed in the hope that it will be useful, 

15# but WITHOUT ANY WARRANTY; without even the implied warranty of 

16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

17# GNU General Public License for more details. 

18# 

19# You should have received a copy of the GNU General Public License 

20# along with this program. If not, see <https://www.gnu.org/licenses/>. 

21 

22__all__ = ('InitialSkyWcsError', 'createInitialSkyWcs', 'bboxFromIraf') 

23 

24import re 

25import lsst.geom as geom 

26 

27from lsst.afw.cameraGeom import PIXELS, FIELD_ANGLE 

28from lsst.afw.image import RotType 

29from lsst.afw.geom.skyWcs import makeSkyWcs 

30import lsst.pex.exceptions 

31 

32 

33class InitialSkyWcsError(Exception): 

34 """For handling failures when creating a SkyWcs from a camera geometry and 

35 boresight. 

36 

37 Typically used as a chained exception from a lower level exception. 

38 """ 

39 pass 

40 

41 

42def createInitialSkyWcs(visitInfo, detector, flipX=False): 

43 """Create a SkyWcs from the telescope boresight and detector geometry. 

44 

45 A typical usecase for this is to create the initial WCS for a newly-read 

46 raw exposure. 

47 

48 

49 Parameters 

50 ---------- 

51 visitInfo : `lsst.afw.image.VisitInfo` 

52 Where to get the telescope boresight and rotator angle from. 

53 detector : `lsst.afw.cameraGeom.Detector` 

54 Where to get the camera geomtry from. 

55 flipX : `bool`, optional 

56 If False, +X is along W, if True +X is along E. 

57 

58 Returns 

59 ------- 

60 skyWcs : `lsst.afw.geom.SkyWcs` 

61 The new composed WCS. 

62 

63 Raises 

64 ------ 

65 InitialSkyWcsError 

66 Raised if there is an error generating the SkyWcs, chained from the 

67 lower-level exception if available. 

68 """ 

69 if visitInfo.getRotType() != RotType.SKY: 

70 msg = (f"Cannot create SkyWcs from camera geometry: rotator angle defined using " 

71 f"RotType={visitInfo.getRotType()} instead of SKY.") 

72 raise InitialSkyWcsError(msg) 

73 orientation = visitInfo.getBoresightRotAngle() 

74 boresight = visitInfo.getBoresightRaDec() 

75 try: 

76 pixelsToFieldAngle = detector.getTransform(detector.makeCameraSys(PIXELS), 

77 detector.makeCameraSys(FIELD_ANGLE)) 

78 except lsst.pex.exceptions.InvalidParameterError as e: 

79 raise InitialSkyWcsError("Cannot compute PIXELS to FIELD_ANGLE Transform.") from e 

80 return makeSkyWcs(pixelsToFieldAngle, orientation, flipX, boresight) 

81 

82 

83def bboxFromIraf(irafBBoxStr): 

84 """Return a Box2I corresponding to an IRAF-style BBOX 

85 

86 [x0:x1,y0:y1] where x0 and x1 are the one-indexed start and end columns, and correspondingly 

87 y0 and y1 are the start and end rows. 

88 """ 

89 

90 mat = re.search(r"^\[([-\d]+):([-\d]+),([-\d]+):([-\d]+)\]$", irafBBoxStr) 

91 if not mat: 

92 raise RuntimeError("Unable to parse IRAF-style bbox \"%s\"" % irafBBoxStr) 

93 x0, x1, y0, y1 = [int(_) for _ in mat.groups()] 

94 

95 return geom.BoxI(geom.PointI(x0 - 1, y0 - 1), geom.PointI(x1 - 1, y1 - 1))