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1##################### generated by xml-casa (v2) from imregrid.xml ################## 

2##################### ec3b2b50981cea05bc279bf990506942 ############################## 

3from __future__ import absolute_import 

4import numpy 

5from casatools.typecheck import CasaValidator as _val_ctor 

6_pc = _val_ctor( ) 

7from casatools.coercetype import coerce as _coerce 

8from casatools.errors import create_error_string 

9from .private.task_imregrid import imregrid as _imregrid_t 

10from casatasks.private.task_logging import start_log as _start_log 

11from casatasks.private.task_logging import end_log as _end_log 

12from casatasks.private.task_logging import except_log as _except_log 

13 

14class _imregrid: 

15 """ 

16 imregrid ---- regrid an image onto a template image 

17 

18  

19 Imregrid will regrid an input image onto a new coordinate system from a template image 

20 or to a new directional reference frame. If a template image is used, then the input and 

21 template images must have the same coordinate structure. 

22 

23 --------- parameter descriptions --------------------------------------------- 

24 

25 imagename Name of the source image 

26 template A dictionary, refcode, or name of an image that provides the output shape and coordinate system 

27 output Name for the regridded image 

28 asvelocity Regrid spectral axis in velocity space rather than frequency space? 

29 axes The pixel axes to regrid. -1 => all. 

30 shape Shape of the output image. Only used if template is an image. If not specified (-1), the output image shape will be the same as the template image shape along the axes that are regridded and the same as input image shape along the axes which are not regridded. 

31 interpolation The interpolation method. One of "nearest", "linear", "cubic". 

32 decimate Decimation factor for coordinate grid computation 

33 replicate Replicate image rather than regrid? 

34 overwrite Overwrite (unprompted) pre-existing output file? 

35 

36 --------- examples ----------------------------------------------------------- 

37 

38  

39 The imregrid task currently finds the nearest input pixel center and interpolates to the output pixel center. 

40 No averaging is done in any direction! 

41  

42 Imregrid will regrid an input image onto a new coordinate system from a template image 

43 or to a new directional reference frame. If a template image is used, then the input and 

44 template images must have the same coordinate structure. 

45  

46 Keyword arguments: 

47  

48 imagename Name of the source image that needs to be regridded. Must be specified. 

49 example: imagename='orion.image' 

50 template Dictionary, directional reference code, or imagename defining the new 

51 shape and coordinate system, or 'get' to return the template 

52 dictionary for imagename. Recognized directional reference codes are: 

53 'J2000', 'B1950', 'B1950_VLA', 'GALACTIC', 'HADEC', 'AZEL', 

54 'AZELSW', 'AZELNE', 'ECLIPTIC', 'MECLIPTIC', 'TECLIPTIC', 

55 and 'SUPERGAL'. 

56 default: 'get'; example: template='orion_j2000.im' (for a template image), 

57 template='J2000' (to regrid the input image to J2000 coordinates). 

58 shape Shape of the output image. Only used if template is an image. 

59 If not specified (-1), the output image will be the same as the template image 

60 shape along the axes which are regridded and the same as the input image shpae 

61 along the axes which are not regridded. If specified and the axis ordering between 

62 the input image and the template are not the same, the values in the array correspond 

63 to the axis ordering of the input image; the output image will have the same axis 

64 ordering as the input image. Ignored if template is set equal to a 

65 reference code. If template is a dictionary, the output shape is 

66 retrieved from the dictionary so the shape input parameter is ignored. 

67 output Name for the regridded image. Must be specified. 

68 example: imagename='orion_shifted.im' 

69 asvelocity If True, regrid spectral axis with respect to velocity, not frequency. If False, 

70 regrid with respect to frequency. default: True 

71 axes The pixel axes to regrid. Default value [-1] => all except Stokes. Ignored 

72 if template is set equal to a reference code (in which case only the directional 

73 axes are regridded). If specified, this should 

74 be provided as an array. example axes=[0,1] (only regrid the first two axes, which 

75 are normally the directional axes). 

76 interpolation The interpolation method. One of 'nearest', 'linear', 'cubic'. 

77 decimate Decimation factor for coordinate grid computation 

78 replicate Replicate image rather than regrid? 

79 overwrite"> Overwrite (unprompted) pre-existing output file? 

80  

81 The new coordinate system is defined by the template parameter, which can be: 

82  

83 * a recognized directional reference frame string. This will rotate the image and the coordinate system so that 

84 the new reference frame's axes are aligned to the cardinal directions (left-right, up-down). 

85 Rotation occurs about the center direction pixel. If this pixel is not the reference pixel, 

86 a temporary copy of the original image is created and the coordinate system is adjusted so 

87 the center direction pixel is the reference pixel. The coordinate system of the input image 

88 is not modified and the output image's reference direction pixel is the center pixel. 

89 Note that the conversion between one frame and another in general becomes less accurate 

90 as distance from the output image's reference pixel increases. Before the rotation occurs, the 

91 image is padded with masked pixels to ensure that all good pixels are used in the rotation (ie the 

92 corners of the image are not cropped after the rotation). After the image is rotated, any masked slices 

93 remaining along the edges of the image in the directional coordinate are cropped, so that there are 

94 no masked slices in the directional coordinate along the edges of the final image. 

95 * a {'csys': [valid coordinate system dictionary], 'shap': [int array describing the output shape]} dictionary. 

96 This is normally obtained by first running regrid with template='get'. In this case imregrid returns the 

97 necessary dictionary. 

98 * 'get', which does not regrid but returns the template dictionary 

99 for imagename, suitable for modification and reuse (see the point immediately above), or 

100 * the name of an image from which to get the coordinate system and shape. 

101 The input and template images must have the same 

102 coordinate structure. 

103  

104 Regridding of complex-valued images is supported. The real and imaginary parts are 

105 regridded independently and the resulting regridded pixel values are combined to 

106 form the regridded, complex-valued image. 

107  

108 The argument {stfaf replicate} can be used to simply replicate pixels 

109 rather than regridding them. Normally ({stfaf replicate=F}), for every 

110 output pixel, its world coordinate is computed and the corresponding 

111 input pixel found (then a little interpolation grid is generated). If 

112 you set {stfaf replicate=T}, then what happens is that for every output 

113 axis, a vector of regularly sampled input pixels is generated (based on 

114 the ratio of the output and input axis shapes). So this just means the 

115 pixels get replicated (by whatever interpolation scheme you use) rather 

116 than regridded in world coordinate space. This process is much faster, 

117 but its not a true world coordinate based regrid. 

118  

119 As decribed above, when {stfaf replicate} is False, a coordinate is 

120 computed for each output pixel; this is an expensive operation. The 

121 argument {stfaf decimate} allows you to decimate the computation of 

122 that coordinate grid to a sparse grid, which is then filled in via fast 

123 interpolation. The default for {stfaf decimate} is 10. The number of 

124 pixels per axis in the sparse grid is the number of output pixels for 

125 that axis divided by the decimation factor. A factor of 10 does pretty 

126 well. You may find that for very non-linear coordinate systems (e.g. 

127 very close to the pole) that you have to reduce the decimation factor. 

128 You may also have to reduce the decimation factor if the number of pixels 

129 in the output image along an axis to be regridded is less than about 50, or 

130 the output image may be completely masked. 

131  

132 If one of the axes to be regridded is a spectral axis and asvelocity=T, 

133 the axis will be regridded to match the velocity, not the frequency, 

134 coordinate of the template coordinate system. Thus the output pixel 

135 values will correspond only to the velocity, not the frequency, of the 

136 output axis. 

137  

138 A variety of interpolation schemes are provided (only 

139 the first three characters to be specified). The cubic interpolation 

140 is substantially slower than linear, and often the improvement is 

141 modest. By default linear interpolation is used. 

142  

143 If an image has per-plane beams and one attempts to regrid the spectral axis, 

144 an exception is thrown. 

145  

146 RULES USED FOR GENERATING OUTPUT IMAGES IN SPECIFIC CASES 

147  

148 There are numerous rules governing the shape and coordinate system of the output 

149 image depending on the input image, template image, and wheher default values of the 

150 axes and shape parameters are used. They are enumerated below. 

151  

152 NOTE: If you want to be certain of what type of output you will get, it is highly 

153 recommended you specify both axes and shape to avoid any ambiguity. 

154  

155 1. Rules governing Stokes axes 

156 1.1. If the input image has no stokes axis, then the output image will have no stokes axis. 

157 1.2. If the input image has a stokes axis, but the template image/coordinate system does not, 

158 and if the default value of the shape parameter is used or if shape is specified and the 

159 specified value for the length stokes axis in equal to the length of the input image 

160 stokes axis, then all stokes in the input 

161 image will be present in the output image 

162 1.3. If the input image has a stokes axis, but the template image/coordinate system does not, 

163 and if the value of the shape parameter is specified but the length of the resulting stokes 

164 axis is not equal to the length of the input image's stokes axis, a failure will occur. 

165 1.4. If the input image has a stokes axis, if the template parameter is an image name, and if the 

166 template image has a degenerate stokes axis, if the axes parameter is not specified or is specified 

167 but does not contain the input stokes axis number, and if the shape parameter is not specified, then 

168 all stokes planes in the input image will be present in the output image. 

169 1.5. If the input image has a stokes axis, if the template parameter is an image name, and if the 

170 template image has a degenerate stokes axis, if the axes parameter is not specified or is specified 

171 but does not contain the input stokes axis number, if the shape parameter is specified, and if the 

172 specified length of the stokes axis is not equal to the length of the input stokes axis, then 

173 a failure will occur. 

174 1.6. If the input image has a stokes axis, if the template parameter is an image name, if the 

175 template image has a degenerate stokes axis, if the axes parameter is specified contains the 

176 input stokes axis number, then use the applicable rule of rules 1.7. and 1.8. for the template 

177 image having a nondegenerate stokes axis. 

178 1.7. If the input image has a stokes axis, if the template parameter is an image name, if the 

179 template image has a nondegenerate stokes axis, and if axes is not specified or if it is, it contains 

180 the input stokes axis number, then only the stokes parameters common to both the input image and 

181 the template image will be present in the output image. If the input image and the template image 

182 have no common stokes parameters, failure will occur. If shape is specified and the length of the 

183 specified stokes axis is not equal to the number of common stokes parameters in the input image and 

184 the template image, then failure will result. 

185 1.8. If the input image has a stokes axis, if the template parameter is an image name, if the 

186 template image has a nondegenerate stokes axis, and if axes is specified but does not contain the input 

187 image stokes axis number, then all stokes present in the input image will be present in the output image. 

188 If shape is also specified but the length of the specified stokes axis does not equal the length of 

189 the input stokes axis, then failure will result. 

190  

191 2. Rules governing spectral axes 

192 In all cases, if the shape parameter is specified, the spectral axis length must be consistent with what 

193 one would normally expect in the special cases, or a failure will result. 

194 2.1. If the input image does not have a spectral axis, then the output image will not have a spectral axis. 

195 2.2. If the input image has a degenerate spectral axis, if the template parameter is an image name, and if the 

196 template image has a spectral axis, if axes is not specified or if it is and does not 

197 contain the input image spectral axis number, then the spectral coordinate of the input image is copied 

198 to the output image and the output image will have a degenerate spectral axis. 

199 2.3. If the input image has a degenerate spectral axis, if the template parameter is an image name, and if the 

200 template image has a spectral axis, if axes is specified and it 

201 contains the input image spectral axis number, then the spectral coordinate of the template image is copied 

202 to the output image. If shape is not specified, the output image will have the same number of channels 

203 as the input image. If shape is specified, the output image will have the number of channels as specified 

204 in shape for the spectral axis. In these cases, the pixel and mask values for all spectral hyperplanes 

205 will be identical; the regridded single spectral plane is simply replicated n times, where n is the 

206 number of channels in the output image. 

207 2.4. If the input image has a spectral axis, if the template parameter is an image name, and if the 

208 template image does not have a spectral axis, if axes is not specified or if it is and does not 

209 contain the input image spectral axis number, then the spectral coordinate of the input image is copied 

210 to the output image and the output image will have the same number of channels as the input image. 

211 2.5. If the input image has a spectral axis, if the template parameter is an image name, if the 

212 template image does not have a spectral axis, if axes is specified it 

213 contains the input image spectral axis number, then failure will result. 

214 2.6. If the input image has a spectral axis, if the template parameter is an image name, if the 

215 template image has a degenerate spectral axis, and if axes is unspecified or if it is but does not 

216 contain the spectral axis number of the input image, the spectral coordinate of the input image is 

217 copied to the output image and the output image will have the same number of channels as the input 

218 image. 

219 2.7. If the input image has a spectral axis, if the template parameter is an image name, if the 

220 template image has a nondegenerate spectral axis, and if axes is unspecified or if it is and 

221 contains the spectral axis number of the input image, regrid the spectral axis of the input to 

222 match the spectral axis of the template. 

223  

224 IMPORTANT NOTE ABOUT FLUX CONSERVATION 

225 in general regridding is inaccurate for images that the angular resolution is poorly 

226 sampled. A check is done for such cases and a warning message is emitted if a beam present. 

227 However, no such check is done if there is no beam present. To add a restoring beam to 

228 an image, use ia.setrestoringbeam(). 

229  

230 Basic Examples 

231  

232 # Regrid an image to the "B1950" or "GALACTIC" coordinate systems 

233  

234 imregrid(imagename="input.image", output="output.image", template="B1950") 

235 imregrid(imagename="input.image", output="output.image", template="GALACTIC") 

236  

237 Note that when regridding to another coordinate system in the manner above, if the 

238 input image's direction coordinate is already in the frame specified by template, 

239 a straight copy of the image is made. No regridding is actually done. 

240  

241 # Obtain a template dictionary from an image and then use it to regrid another image 

242  

243 temp_dict = imregrid(imagename="target.image", template="get") 

244 imregrid(imagename="input.image", output="output.image", template=temp_dict) 

245  

246 In this example, the template="get" option is used in the first command in order to 

247 characterize the desired shape and coordinate system used, and a new dictionary, 

248 temp_dict, is generated accordingly. This is then used when performing the actual 

249 regridding of input.image in the second command. 

250  

251  

252 More Advanced Examples 

253  

254 It is also possible to directly use a template image for regridding with imregrid. 

255 For this to work reliably and predictably, the dimensionality (i.e. which 

256 dimensions are present in an image) and the axis ordering of the input image must 

257 be the same. The type and ordering of the axes of both the input and template 

258 images can (and should) first be examined using the CASA imhead task. Any 

259 necessary reordering of axes can be performed using the CASA imtrans task. 

260  

261 Unless the user explicitly specifies which dimensions to regrid using the axes 

262 parameter (see the following example), imregrid will also attempt to regrid 

263 degenerate axes (i.e. image axes of length one pixel). Stokes axes are never 

264 regridded. 

265  

266 In the case where template is an image name and the default value of shape is specified, 

267 the output image's shape will be the same as the template image's shape along the axes which 

268 are regridded and the same as the input image's shape along the axes which are not regridded. 

269 So for example, if the input image has a shape of [20, 30, 40] and the template image has a shape 

270 of [10, 40, 70] and only axes=[0, 1], the output image will have a shape of [10, 40, 40]. If axes=[2], 

271 the output image will have a shape of [20, 30, 70]. 

272  

273 # Regrid input.image by directly using target.image as a template 

274  

275 imregrid(imagename="input.image", output="output.image", template="target.image", shape=[500,500,40,1]) 

276  

277 In this example, it is assumed that the axis order of the input image is of the 

278 form (direction_x, direction_y, spectral, Stokes), where 'direction_x' and 'direction_y' 

279 are the directional coordinates on the sky (in some reference frame), 

280 'spectral' is a velocity/frequency axis, and 'Stokes' contains polarization 

281 information. In this example, input.image might typically be a data cube of 

282 shape [100, 100, 40, 1]. Note that the default value of asvelocity (True) will be used so that 

283 the spectral axis will be regridded to the same velocity system as that of the template image. 

284  

285  

286 # Regrid only the first two axes of an image 

287  

288 Firstly, the user should inspect the type and ordering of the axes with imhead, 

289 and then correct with imtrans if necessary. 

290  

291 imregrid(imagename="input.image", output="output.image", template="target.image", axes=[0,1]) 

292  

293 The above command will regrid only the first two axes (normally the directional axes) of input.image and 

294 leave all other axes unchanged. The output image will have the shape of the template image along the regridded 

295 axes [0, 1] and the shape of the input image along the other axes since the shape parameter was not 

296 explicitly specified. 

297  

298  

299 # Regrid the third axis, considering velocity rather than frequency units 

300  

301 imregrid(imagename="input.image", output="output.image", template="target.image", axes=[2], asvelocity=True) 

302  

303 This example regrids the spectral axis (zero-based axis number 2) with respect to velocity because the asvelocity parameter 

304 has been set to True. This is useful when eg, regridding a cube containing one spectral line to match the velocity coordinate 

305 of another cube containing a different spectral line. 

306  

307  

308 # Regrid the third axis, considering velocity rather than frequency units but first set the rest frequency 

309  

310 imhead("input.image", mode="put", hdkey="restfreq", hdvalue="110GHz") 

311 imregrid(imagename="input.image", output="output.image", template="target.image", axes=[2], asvelocity=True) 

312  

313 The first command in this example uses the imhead task to set the value of the 

314 image rest frequency to a value of 110GHz in input.image. The following 

315 imregrid command then performs a frequency units regridding only of the third 

316 axis listed (zero-based axis) (2), taking account of the input.image rest frequency in the input file. 

317 

318 

319 """ 

320 

321 _info_group_ = """analysis""" 

322 _info_desc_ = """regrid an image onto a template image""" 

323 

324 def __call__( self, imagename='', template='get', output='', asvelocity=True, axes=[ int(-1) ], shape=[ int(-1) ], interpolation='linear', decimate=int(10), replicate=False, overwrite=False ): 

325 schema = {'imagename': {'type': 'cReqPath', 'coerce': _coerce.expand_path}, 'template': {'type': 'cVariant', 'coerce': [_coerce.to_variant]}, 'output': {'type': 'cStr', 'coerce': _coerce.to_str}, 'asvelocity': {'type': 'cBool'}, 'axes': {'type': 'cIntVec', 'coerce': [_coerce.to_list,_coerce.to_intvec]}, 'shape': {'type': 'cIntVec', 'coerce': [_coerce.to_list,_coerce.to_intvec]}, 'interpolation': {'type': 'cStr', 'coerce': _coerce.to_str}, 'decimate': {'type': 'cInt'}, 'replicate': {'type': 'cBool'}, 'overwrite': {'type': 'cBool'}} 

326 doc = {'imagename': imagename, 'template': template, 'output': output, 'asvelocity': asvelocity, 'axes': axes, 'shape': shape, 'interpolation': interpolation, 'decimate': decimate, 'replicate': replicate, 'overwrite': overwrite} 

327 assert _pc.validate(doc,schema), create_error_string(_pc.errors) 

328 _logging_state_ = _start_log( 'imregrid', [ 'imagename=' + repr(_pc.document['imagename']), 'template=' + repr(_pc.document['template']), 'output=' + repr(_pc.document['output']), 'asvelocity=' + repr(_pc.document['asvelocity']), 'axes=' + repr(_pc.document['axes']), 'shape=' + repr(_pc.document['shape']), 'interpolation=' + repr(_pc.document['interpolation']), 'decimate=' + repr(_pc.document['decimate']), 'replicate=' + repr(_pc.document['replicate']), 'overwrite=' + repr(_pc.document['overwrite']) ] ) 

329 task_result = None 

330 try: 

331 task_result = _imregrid_t( _pc.document['imagename'], _pc.document['template'], _pc.document['output'], _pc.document['asvelocity'], _pc.document['axes'], _pc.document['shape'], _pc.document['interpolation'], _pc.document['decimate'], _pc.document['replicate'], _pc.document['overwrite'] ) 

332 except Exception as exc: 

333 _except_log('imregrid', exc) 

334 raise 

335 finally: 

336 task_result = _end_log( _logging_state_, 'imregrid', task_result ) 

337 return task_result 

338 

339imregrid = _imregrid( ) 

340