| /*============================================================================ | |
| WCSLIB 6.2 - an implementation of the FITS WCS standard. | |
| Copyright (C) 1995-2018, Mark Calabretta | |
| This file is part of WCSLIB. | |
| WCSLIB is free software: you can redistribute it and/or modify it under the | |
| terms of the GNU Lesser General Public License as published by the Free | |
| Software Foundation, either version 3 of the License, or (at your option) | |
| any later version. | |
| WCSLIB is distributed in the hope that it will be useful, but WITHOUT ANY | |
| WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | |
| FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for | |
| more details. | |
| You should have received a copy of the GNU Lesser General Public License | |
| along with WCSLIB. If not, see http://www.gnu.org/licenses. | |
| Direct correspondence concerning WCSLIB to mark@calabretta.id.au | |
| Author: Mark Calabretta, Australia Telescope National Facility, CSIRO. | |
| http://www.atnf.csiro.au/people/Mark.Calabretta | |
| $Id: wcshdr.h,v 6.2 2018/10/20 10:03:13 mcalabre Exp $ | |
| *============================================================================= | |
| * | |
| * WCSLIB 6.2 - C routines that implement the FITS World Coordinate System | |
| * (WCS) standard. Refer to the README file provided with WCSLIB for an | |
| * overview of the library. | |
| * | |
| * | |
| * Summary of the wcshdr routines | |
| * ------------------------------ | |
| * Routines in this suite are aimed at extracting WCS information from a FITS | |
| * file. The information is encoded via keywords defined in | |
| * | |
| = "Representations of world coordinates in FITS", | |
| = Greisen, E.W., & Calabretta, M.R. 2002, A&A, 395, 1061 (WCS Paper I) | |
| = | |
| = "Representations of celestial coordinates in FITS", | |
| = Calabretta, M.R., & Greisen, E.W. 2002, A&A, 395, 1077 (WCS Paper II) | |
| = | |
| = "Representations of spectral coordinates in FITS", | |
| = Greisen, E.W., Calabretta, M.R., Valdes, F.G., & Allen, S.L. | |
| = 2006, A&A, 446, 747 (WCS Paper III) | |
| = | |
| = "Representations of distortions in FITS world coordinate systems", | |
| = Calabretta, M.R. et al. (WCS Paper IV, draft dated 2004/04/22), | |
| = available from http://www.atnf.csiro.au/people/Mark.Calabretta | |
| = | |
| = "Representations of time coordinates in FITS - | |
| = Time and relative dimension in space", | |
| = Rots, A.H., Bunclark, P.S., Calabretta, M.R., Allen, S.L., | |
| = Manchester, R.N., & Thompson, W.T. 2015, A&A, 574, A36 (WCS Paper VII) | |
| * | |
| * These routines provide the high-level interface between the FITS file and | |
| * the WCS coordinate transformation routines. | |
| * | |
| * Additionally, function wcshdo() is provided to write out the contents of a | |
| * wcsprm struct as a FITS header. | |
| * | |
| * Briefly, the anticipated sequence of operations is as follows: | |
| * | |
| * - 1: Open the FITS file and read the image or binary table header, e.g. | |
| * using CFITSIO routine fits_hdr2str(). | |
| * | |
| * - 2: Parse the header using wcspih() or wcsbth(); they will automatically | |
| * interpret 'TAB' header keywords using wcstab(). | |
| * | |
| * - 3: Allocate memory for, and read 'TAB' arrays from the binary table | |
| * extension, e.g. using CFITSIO routine fits_read_wcstab() - refer to | |
| * the prologue of getwcstab.h. wcsset() will automatically take | |
| * control of this allocated memory, in particular causing it to be | |
| * free'd by wcsfree(). | |
| * | |
| * - 4: Translate non-standard WCS usage using wcsfix(), see wcsfix.h. | |
| * | |
| * - 5: Initialize wcsprm struct(s) using wcsset() and calculate coordinates | |
| * using wcsp2s() and/or wcss2p(). Refer to the prologue of wcs.h for a | |
| * description of these and other high-level WCS coordinate | |
| * transformation routines. | |
| * | |
| * - 6: Clean up by freeing memory with wcsvfree(). | |
| * | |
| * In detail: | |
| * | |
| * - wcspih() is a high-level FITS WCS routine that parses an image header. It | |
| * returns an array of up to 27 wcsprm structs on each of which it invokes | |
| * wcstab(). | |
| * | |
| * - wcsbth() is the analogue of wcspih() for use with binary tables; it | |
| * handles image array and pixel list keywords. As an extension of the FITS | |
| * WCS standard, it also recognizes image header keywords which may be used | |
| * to provide default values via an inheritance mechanism. | |
| * | |
| * - wcstab() assists in filling in members of the wcsprm struct associated | |
| * with coordinate lookup tables ('TAB'). These are based on arrays stored | |
| * in a FITS binary table extension (BINTABLE) that are located by PVi_ma | |
| * keywords in the image header. | |
| * | |
| * - wcsidx() and wcsbdx() are utility routines that return the index for a | |
| * specified alternate coordinate descriptor in the array of wcsprm structs | |
| * returned by wcspih() or wcsbth(). | |
| * | |
| * - wcsvfree() deallocates memory for an array of wcsprm structs, such as | |
| * returned by wcspih() or wcsbth(). | |
| * | |
| * - wcshdo() writes out a wcsprm struct as a FITS header. | |
| * | |
| * | |
| * wcspih() - FITS WCS parser routine for image headers | |
| * ---------------------------------------------------- | |
| * wcspih() is a high-level FITS WCS routine that parses an image header, | |
| * either that of a primary HDU or of an image extension. All WCS keywords | |
| * defined in Papers I, II, III, IV, and VII are recognized, and also those | |
| * used by the AIPS convention and certain other keywords that existed in early | |
| * drafts of the WCS papers as explained in wcsbth() note 5. wcspih() also | |
| * handles keywords associated with non-standard distortion functions described | |
| * in the prologue of dis.h. | |
| * | |
| * Given a character array containing a FITS image header, wcspih() identifies | |
| * and reads all WCS keywords for the primary coordinate representation and up | |
| * to 26 alternate representations. It returns this information as an array of | |
| * wcsprm structs. | |
| * | |
| * wcspih() invokes wcstab() on each of the wcsprm structs that it returns. | |
| * | |
| * Use wcsbth() in preference to wcspih() for FITS headers of unknown type; | |
| * wcsbth() can parse image headers as well as binary table and pixel list | |
| * headers, although it cannot handle keywords relating to distortion | |
| * functions, which may only exist in a primary image header. | |
| * | |
| * Given and returned: | |
| * header char[] Character array containing the (entire) FITS image | |
| * header from which to identify and construct the | |
| * coordinate representations, for example, as might be | |
| * obtained conveniently via the CFITSIO routine | |
| * fits_hdr2str(). | |
| * | |
| * Each header "keyrecord" (formerly "card image") | |
| * consists of exactly 80 7-bit ASCII printing characters | |
| * in the range 0x20 to 0x7e (which excludes NUL, BS, | |
| * TAB, LF, FF and CR) especially noting that the | |
| * keyrecords are NOT null-terminated. | |
| * | |
| * For negative values of ctrl (see below), header[] is | |
| * modified so that WCS keyrecords processed by wcspih() | |
| * are removed from it. | |
| * | |
| * Given: | |
| * nkeyrec int Number of keyrecords in header[]. | |
| * | |
| * relax int Degree of permissiveness: | |
| * 0: Recognize only FITS keywords defined by the | |
| * published WCS standard. | |
| * WCSHDR_all: Admit all recognized informal | |
| * extensions of the WCS standard. | |
| * Fine-grained control of the degree of permissiveness | |
| * is also possible as explained in wcsbth() note 5. | |
| * | |
| * ctrl int Error reporting and other control options for invalid | |
| * WCS and other header keyrecords: | |
| * 0: Do not report any rejected header keyrecords. | |
| * 1: Produce a one-line message stating the number | |
| * of WCS keyrecords rejected (nreject). | |
| * 2: Report each rejected keyrecord and the reason | |
| * why it was rejected. | |
| * 3: As above, but also report all non-WCS | |
| * keyrecords that were discarded, and the number | |
| * of coordinate representations (nwcs) found. | |
| * 4: As above, but also report the accepted WCS | |
| * keyrecords, with a summary of the number | |
| * accepted as well as rejected. | |
| * The report is written to stderr by default, or the | |
| * stream set by wcsprintf_set(). | |
| * | |
| * For ctrl < 0, WCS keyrecords processed by wcspih() | |
| * are removed from header[]: | |
| * -1: Remove only valid WCS keyrecords whose values | |
| * were successfully extracted, nothing is | |
| * reported. | |
| * -2: As above, but also remove WCS keyrecords that | |
| * were rejected, reporting each one and the | |
| * reason that it was rejected. | |
| * -3: As above, and also report the number of | |
| * coordinate representations (nwcs) found. | |
| * -11: Same as -1 but preserving global WCS-related | |
| * keywords such as '{DATE,MJD}-{OBS,BEG,AVG,END}' | |
| * and the other basic time-related keywords, and | |
| * 'OBSGEO-{X,Y,Z,L,B,H}'. | |
| * If any keyrecords are removed from header[] it will | |
| * be null-terminated (NUL not being a legal FITS header | |
| * character), otherwise it will contain its original | |
| * complement of nkeyrec keyrecords and possibly not be | |
| * null-terminated. | |
| * | |
| * Returned: | |
| * nreject int* Number of WCS keywords rejected for syntax errors, | |
| * illegal values, etc. Keywords not recognized as WCS | |
| * keywords are simply ignored. Refer also to wcsbth() | |
| * note 5. | |
| * | |
| * nwcs int* Number of coordinate representations found. | |
| * | |
| * wcs struct wcsprm** | |
| * Pointer to an array of wcsprm structs containing up to | |
| * 27 coordinate representations. | |
| * | |
| * Memory for the array is allocated by wcspih() which | |
| * also invokes wcsini() for each struct to allocate | |
| * memory for internal arrays and initialize their | |
| * members to default values. Refer also to wcsbth() | |
| * note 8. Note that wcsset() is not invoked on these | |
| * structs. | |
| * | |
| * This allocated memory must be freed by the user, first | |
| * by invoking wcsfree() for each struct, and then by | |
| * freeing the array itself. A routine, wcsvfree(), is | |
| * provided to do this (see below). | |
| * | |
| * Function return value: | |
| * int Status return value: | |
| * 0: Success. | |
| * 1: Null wcsprm pointer passed. | |
| * 2: Memory allocation failed. | |
| * 4: Fatal error returned by Flex parser. | |
| * | |
| * Notes: | |
| * Refer to wcsbth() notes 1, 2, 3, 5, 7, and 8. | |
| * | |
| * | |
| * wcsbth() - FITS WCS parser routine for binary table and image headers | |
| * --------------------------------------------------------------------- | |
| * wcsbth() is a high-level FITS WCS routine that parses a binary table header. | |
| * It handles image array and pixel list WCS keywords which may be present | |
| * together in one header. | |
| * | |
| * As an extension of the FITS WCS standard, wcsbth() also recognizes image | |
| * header keywords in a binary table header. These may be used to provide | |
| * default values via an inheritance mechanism discussed in note 5 (c.f. | |
| * WCSHDR_AUXIMG and WCSHDR_ALLIMG), or may instead result in wcsprm structs | |
| * that are not associated with any particular column. Thus wcsbth() can | |
| * handle primary image and image extension headers in addition to binary table | |
| * headers (it ignores NAXIS and does not rely on the presence of the TFIELDS | |
| * keyword). | |
| * | |
| * All WCS keywords defined in Papers I, II, III, and VII are recognized, and | |
| * also those used by the AIPS convention and certain other keywords that | |
| * existed in early drafts of the WCS papers as explained in note 5 below. | |
| * | |
| * wcsbth() sets the colnum or colax[] members of the wcsprm structs that it | |
| * returns with the column number of an image array or the column numbers | |
| * associated with each pixel coordinate element in a pixel list. wcsprm | |
| * structs that are not associated with any particular column, as may be | |
| * derived from image header keywords, have colnum == 0. | |
| * | |
| * Note 6 below discusses the number of wcsprm structs returned by wcsbth(), | |
| * and the circumstances in which image header keywords cause a struct to be | |
| * created. See also note 9 concerning the number of separate images that may | |
| * be stored in a pixel list. | |
| * | |
| * The API to wcsbth() is similar to that of wcspih() except for the addition | |
| * of extra arguments that may be used to restrict its operation. Like | |
| * wcspih(), wcsbth() invokes wcstab() on each of the wcsprm structs that it | |
| * returns. | |
| * | |
| * Given and returned: | |
| * header char[] Character array containing the (entire) FITS binary | |
| * table, primary image, or image extension header from | |
| * which to identify and construct the coordinate | |
| * representations, for example, as might be obtained | |
| * conveniently via the CFITSIO routine fits_hdr2str(). | |
| * | |
| * Each header "keyrecord" (formerly "card image") | |
| * consists of exactly 80 7-bit ASCII printing | |
| * characters in the range 0x20 to 0x7e (which excludes | |
| * NUL, BS, TAB, LF, FF and CR) especially noting that | |
| * the keyrecords are NOT null-terminated. | |
| * | |
| * For negative values of ctrl (see below), header[] is | |
| * modified so that WCS keyrecords processed by wcsbth() | |
| * are removed from it. | |
| * | |
| * Given: | |
| * nkeyrec int Number of keyrecords in header[]. | |
| * | |
| * relax int Degree of permissiveness: | |
| * 0: Recognize only FITS keywords defined by the | |
| * published WCS standard. | |
| * WCSHDR_all: Admit all recognized informal | |
| * extensions of the WCS standard. | |
| * Fine-grained control of the degree of permissiveness | |
| * is also possible, as explained in note 5 below. | |
| * | |
| * ctrl int Error reporting and other control options for invalid | |
| * WCS and other header keyrecords: | |
| * 0: Do not report any rejected header keyrecords. | |
| * 1: Produce a one-line message stating the number | |
| * of WCS keyrecords rejected (nreject). | |
| * 2: Report each rejected keyrecord and the reason | |
| * why it was rejected. | |
| * 3: As above, but also report all non-WCS | |
| * keyrecords that were discarded, and the number | |
| * of coordinate representations (nwcs) found. | |
| * 4: As above, but also report the accepted WCS | |
| * keyrecords, with a summary of the number | |
| * accepted as well as rejected. | |
| * The report is written to stderr by default, or the | |
| * stream set by wcsprintf_set(). | |
| * | |
| * For ctrl < 0, WCS keyrecords processed by wcsbth() | |
| * are removed from header[]: | |
| * -1: Remove only valid WCS keyrecords whose values | |
| * were successfully extracted, nothing is | |
| * reported. | |
| * -2: Also remove WCS keyrecords that were rejected, | |
| * reporting each one and the reason that it was | |
| * rejected. | |
| * -3: As above, and also report the number of | |
| * coordinate representations (nwcs) found. | |
| * -11: Same as -1 but preserving global WCS-related | |
| * keywords such as '{DATE,MJD}-{OBS,BEG,AVG,END}' | |
| * and the other basic time-related keywords, and | |
| * 'OBSGEO-{X,Y,Z,L,B,H}'. | |
| * If any keyrecords are removed from header[] it will | |
| * be null-terminated (NUL not being a legal FITS header | |
| * character), otherwise it will contain its original | |
| * complement of nkeyrec keyrecords and possibly not be | |
| * null-terminated. | |
| * | |
| * keysel int Vector of flag bits that may be used to restrict the | |
| * keyword types considered: | |
| * WCSHDR_IMGHEAD: Image header keywords. | |
| * WCSHDR_BIMGARR: Binary table image array. | |
| * WCSHDR_PIXLIST: Pixel list keywords. | |
| * If zero, there is no restriction. | |
| * | |
| * Keywords such as EQUIna or RFRQna that are common to | |
| * binary table image arrays and pixel lists (including | |
| * WCSNna and TWCSna, as explained in note 4 below) are | |
| * selected by both WCSHDR_BIMGARR and WCSHDR_PIXLIST. | |
| * Thus if inheritance via WCSHDR_ALLIMG is enabled as | |
| * discussed in note 5 and one of these shared keywords | |
| * is present, then WCSHDR_IMGHEAD and WCSHDR_PIXLIST | |
| * alone may be sufficient to cause the construction of | |
| * coordinate descriptions for binary table image arrays. | |
| * | |
| * colsel int* Pointer to an array of table column numbers used to | |
| * restrict the keywords considered by wcsbth(). | |
| * | |
| * A null pointer may be specified to indicate that there | |
| * is no restriction. Otherwise, the magnitude of | |
| * cols[0] specifies the length of the array: | |
| * cols[0] > 0: the columns are included, | |
| * cols[0] < 0: the columns are excluded. | |
| * | |
| * For the pixel list keywords TPn_ka and TCn_ka (and | |
| * TPCn_ka and TCDn_ka if WCSHDR_LONGKEY is enabled), it | |
| * is an error for one column to be selected but not the | |
| * other. This is unlike the situation with invalid | |
| * keyrecords, which are simply rejected, because the | |
| * error is not intrinsic to the header itself but | |
| * arises in the way that it is processed. | |
| * | |
| * Returned: | |
| * nreject int* Number of WCS keywords rejected for syntax errors, | |
| * illegal values, etc. Keywords not recognized as WCS | |
| * keywords are simply ignored, refer also to note 5 | |
| * below. | |
| * | |
| * nwcs int* Number of coordinate representations found. | |
| * | |
| * wcs struct wcsprm** | |
| * Pointer to an array of wcsprm structs containing up | |
| * to 27027 coordinate representations, refer to note 6 | |
| * below. | |
| * | |
| * Memory for the array is allocated by wcsbth() which | |
| * also invokes wcsini() for each struct to allocate | |
| * memory for internal arrays and initialize their | |
| * members to default values. Refer also to note 8 | |
| * below. Note that wcsset() is not invoked on these | |
| * structs. | |
| * | |
| * This allocated memory must be freed by the user, first | |
| * by invoking wcsfree() for each struct, and then by | |
| * freeing the array itself. A routine, wcsvfree(), is | |
| * provided to do this (see below). | |
| * | |
| * Function return value: | |
| * int Status return value: | |
| * 0: Success. | |
| * 1: Null wcsprm pointer passed. | |
| * 2: Memory allocation failed. | |
| * 3: Invalid column selection. | |
| * 4: Fatal error returned by Flex parser. | |
| * | |
| * Notes: | |
| * 1: wcspih() determines the number of coordinate axes independently for | |
| * each alternate coordinate representation (denoted by the "a" value in | |
| * keywords like CTYPEia) from the higher of | |
| * | |
| * a: NAXIS, | |
| * b: WCSAXESa, | |
| * c: The highest axis number in any parameterized WCS keyword. The | |
| * keyvalue, as well as the keyword, must be syntactically valid | |
| * otherwise it will not be considered. | |
| * | |
| * If none of these keyword types is present, i.e. if the header only | |
| * contains auxiliary WCS keywords for a particular coordinate | |
| * representation, then no coordinate description is constructed for it. | |
| * | |
| * wcsbth() is similar except that it ignores the NAXIS keyword if given | |
| * an image header to process. | |
| * | |
| * The number of axes, which is returned as a member of the wcsprm | |
| * struct, may differ for different coordinate representations of the | |
| * same image. | |
| * | |
| * 2: wcspih() and wcsbth() enforce correct FITS "keyword = value" syntax | |
| * with regard to "= " occurring in columns 9 and 10. | |
| * | |
| * However, they do recognize free-format character (NOST 100-2.0, | |
| * Sect. 5.2.1), integer (Sect. 5.2.3), and floating-point values | |
| * (Sect. 5.2.4) for all keywords. | |
| * | |
| * 3: Where CROTAn, CDi_ja, and PCi_ja occur together in one header wcspih() | |
| * and wcsbth() treat them as described in the prologue to wcs.h. | |
| * | |
| * 4: WCS Paper I mistakenly defined the pixel list form of WCSNAMEa as | |
| * TWCSna instead of WCSNna; the 'T' is meant to substitute for the axis | |
| * number in the binary table form of the keyword - note that keywords | |
| * defined in WCS Papers II, III, and VII that are not parameterized by | |
| * axis number have identical forms for binary tables and pixel lists. | |
| * Consequently wcsbth() always treats WCSNna and TWCSna as equivalent. | |
| * | |
| * 5: wcspih() and wcsbth() interpret the "relax" argument as a vector of | |
| * flag bits to provide fine-grained control over what non-standard WCS | |
| * keywords to accept. The flag bits are subject to change in future and | |
| * should be set by using the preprocessor macros (see below) for the | |
| * purpose. | |
| * | |
| * - WCSHDR_none: Don't accept any extensions (not even those in the | |
| * errata). Treat non-conformant keywords in the same way as | |
| * non-WCS keywords in the header, i.e. simply ignore them. | |
| * | |
| * - WCSHDR_all: Accept all extensions recognized by the parser. | |
| * | |
| * - WCSHDR_reject: Reject non-standard keyrecords (that are not otherwise | |
| * explicitly accepted by one of the flags below). A message will | |
| * optionally be printed on stderr by default, or the stream set | |
| * by wcsprintf_set(), as determined by the ctrl argument, and | |
| * nreject will be incremented. | |
| * | |
| * This flag may be used to signal the presence of non-standard | |
| * keywords, otherwise they are simply passed over as though they | |
| * did not exist in the header. It is mainly intended for testing | |
| * conformance of a FITS header to the WCS standard. | |
| * | |
| * Keyrecords may be non-standard in several ways: | |
| * | |
| * - The keyword may be syntactically valid but with keyvalue of | |
| * incorrect type or invalid syntax, or the keycomment may be | |
| * malformed. | |
| * | |
| * - The keyword may strongly resemble a WCS keyword but not, in | |
| * fact, be one because it does not conform to the standard. | |
| * For example, "CRPIX01" looks like a CRPIXja keyword, but in | |
| * fact the leading zero on the axis number violates the basic | |
| * FITS standard. Likewise, "LONPOLE2" is not a valid | |
| * LONPOLEa keyword in the WCS standard, and indeed there is | |
| * nothing the parser can sensibly do with it. | |
| * | |
| * - Use of the keyword may be deprecated by the standard. Such | |
| * will be rejected if not explicitly accepted via one of the | |
| * flags below. | |
| * | |
| * - WCSHDR_strict: As for WCSHDR_reject, but also reject AIPS-convention | |
| * keywords and all other deprecated usage that is not explicitly | |
| * accepted. | |
| * | |
| * - WCSHDR_CROTAia: Accept CROTAia (wcspih()), | |
| * iCROTna (wcsbth()), | |
| * TCROTna (wcsbth()). | |
| * - WCSHDR_VELREFa: Accept VELREFa. | |
| * wcspih() always recognizes the AIPS-convention keywords, | |
| * CROTAn, EPOCH, and VELREF for the primary representation | |
| * (a = ' ') but alternates are non-standard. | |
| * | |
| * wcsbth() accepts EPOCHa and VELREFa only if WCSHDR_AUXIMG is | |
| * also enabled. | |
| * | |
| * - WCSHDR_CD00i00j: Accept CD00i00j (wcspih()). | |
| * - WCSHDR_PC00i00j: Accept PC00i00j (wcspih()). | |
| * - WCSHDR_PROJPn: Accept PROJPn (wcspih()). | |
| * These appeared in early drafts of WCS Paper I+II (before they | |
| * were split) and are equivalent to CDi_ja, PCi_ja, and PVi_ma | |
| * for the primary representation (a = ' '). PROJPn is | |
| * equivalent to PVi_ma with m = n <= 9, and is associated | |
| * exclusively with the latitude axis. | |
| * | |
| * - WCSHDR_CD0i_0ja: Accept CD0i_0ja (wcspih()). | |
| * - WCSHDR_PC0i_0ja: Accept PC0i_0ja (wcspih()). | |
| * - WCSHDR_PV0i_0ma: Accept PV0i_0ja (wcspih()). | |
| * - WCSHDR_PS0i_0ma: Accept PS0i_0ja (wcspih()). | |
| * Allow the numerical index to have a leading zero in doubly- | |
| * parameterized keywords, for example, PC01_01. WCS Paper I | |
| * (Sects 2.1.2 & 2.1.4) explicitly disallows leading zeroes. | |
| * The FITS 3.0 standard document (Sect. 4.1.2.1) states that the | |
| * index in singly-parameterized keywords (e.g. CTYPEia) "shall | |
| * not have leading zeroes", and later in Sect. 8.1 that "leading | |
| * zeroes must not be used" on PVi_ma and PSi_ma. However, by an | |
| * oversight, it is silent on PCi_ja and CDi_ja. | |
| * | |
| * - WCSHDR_DOBSn (wcsbth() only): Allow DOBSn, the column-specific | |
| * analogue of DATE-OBS. By an oversight this was never formally | |
| * defined in the standard. | |
| * | |
| * - WCSHDR_OBSGLBHn (wcsbth() only): Allow OBSGLn, OBSGBn, and OBSGHn, | |
| * the column-specific analogues of OBSGEO-L, OBSGEO-B, and | |
| * OBSGEO-H. By an oversight these were never formally defined in | |
| * the standard. | |
| * | |
| * - WCSHDR_RADECSYS: Accept RADECSYS. This appeared in early drafts of | |
| * WCS Paper I+II and was subsequently replaced by RADESYSa. | |
| * | |
| * wcsbth() accepts RADECSYS only if WCSHDR_AUXIMG is also | |
| * enabled. | |
| * | |
| * - WCSHDR_EPOCHa: Accept EPOCHa. | |
| * | |
| * - WCSHDR_VSOURCE: Accept VSOURCEa or VSOUna (wcsbth()). This appeared | |
| * in early drafts of WCS Paper III and was subsequently dropped | |
| * in favour of ZSOURCEa and ZSOUna. | |
| * | |
| * wcsbth() accepts VSOURCEa only if WCSHDR_AUXIMG is also | |
| * enabled. | |
| * | |
| * - WCSHDR_LONGKEY (wcsbth() only): Accept long forms of the alternate | |
| * binary table and pixel list WCS keywords, i.e. with "a" non- | |
| * blank. Specifically | |
| * | |
| # jCRPXna TCRPXna : jCRPXn jCRPna TCRPXn TCRPna CRPIXja | |
| # - TPCn_ka : - ijPCna - TPn_ka PCi_ja | |
| # - TCDn_ka : - ijCDna - TCn_ka CDi_ja | |
| # iCDLTna TCDLTna : iCDLTn iCDEna TCDLTn TCDEna CDELTia | |
| # iCUNIna TCUNIna : iCUNIn iCUNna TCUNIn TCUNna CUNITia | |
| # iCTYPna TCTYPna : iCTYPn iCTYna TCTYPn TCTYna CTYPEia | |
| # iCRVLna TCRVLna : iCRVLn iCRVna TCRVLn TCRVna CRVALia | |
| # iPVn_ma TPVn_ma : - iVn_ma - TVn_ma PVi_ma | |
| # iPSn_ma TPSn_ma : - iSn_ma - TSn_ma PSi_ma | |
| * | |
| * where the primary and standard alternate forms together with | |
| * the image-header equivalent are shown rightwards of the colon. | |
| * | |
| * The long form of these keywords could be described as quasi- | |
| * standard. TPCn_ka, iPVn_ma, and TPVn_ma appeared by mistake | |
| * in the examples in WCS Paper II and subsequently these and | |
| * also TCDn_ka, iPSn_ma and TPSn_ma were legitimized by the | |
| * errata to the WCS papers. | |
| * | |
| * Strictly speaking, the other long forms are non-standard and | |
| * in fact have never appeared in any draft of the WCS papers nor | |
| * in the errata. However, as natural extensions of the primary | |
| * form they are unlikely to be written with any other intention. | |
| * Thus it should be safe to accept them provided, of course, | |
| * that the resulting keyword does not exceed the 8-character | |
| * limit. | |
| * | |
| * If WCSHDR_CNAMn is enabled then also accept | |
| * | |
| # iCNAMna TCNAMna : --- iCNAna --- TCNAna CNAMEia | |
| # iCRDEna TCRDEna : --- iCRDna --- TCRDna CRDERia | |
| # iCSYEna TCSYEna : --- iCSYna --- TCSYna CSYERia | |
| # iCZPHna TCZPHna : --- iCZPna --- TCZPna CZPHSia | |
| # iCPERna TCPERna : --- iCPRna --- TCPRna CPERIia | |
| * | |
| * Note that CNAMEia, CRDERia, CSYERia, CZPHSia, CPERIia, and | |
| * their variants are not used by WCSLIB but are stored in the | |
| * wcsprm struct as auxiliary information. | |
| * | |
| * - WCSHDR_CNAMn (wcsbth() only): Accept iCNAMn, iCRDEn, iCSYEn, iCZPHn, | |
| * iCPERn, TCNAMn, TCRDEn, TCSYEn, TCZPHn, and TCPERn, i.e. with | |
| * "a" blank. While non-standard, these are the obvious analogues | |
| * of iCTYPn, TCTYPn, etc. | |
| * | |
| * - WCSHDR_AUXIMG (wcsbth() only): Allow the image-header form of an | |
| * auxiliary WCS keyword with representation-wide scope to | |
| * provide a default value for all images. This default may be | |
| * overridden by the column-specific form of the keyword. | |
| * | |
| * For example, a keyword like EQUINOXa would apply to all image | |
| * arrays in a binary table, or all pixel list columns with | |
| * alternate representation "a" unless overridden by EQUIna. | |
| * | |
| * Specifically the keywords are: | |
| * | |
| # LONPOLEa for LONPna | |
| # LATPOLEa for LATPna | |
| # VELREF - ... (No column-specific form.) | |
| # VELREFa - ... Only if WCSHDR_VELREFa is set. | |
| * | |
| * whose keyvalues are actually used by WCSLIB, and also keywords | |
| * providing auxiliary information that is simply stored in the | |
| * wcsprm struct: | |
| * | |
| # WCSNAMEa for WCSNna ... Or TWCSna (see below). | |
| # | |
| # DATE-OBS for DOBSn | |
| # MJD-OBS for MJDOBn | |
| # | |
| # RADESYSa for RADEna | |
| # RADECSYS for RADEna ... Only if WCSHDR_RADECSYS is set. | |
| # EPOCH - ... (No column-specific form.) | |
| # EPOCHa - ... Only if WCSHDR_EPOCHa is set. | |
| # EQUINOXa for EQUIna | |
| * | |
| * where the image-header keywords on the left provide default | |
| * values for the column specific keywords on the right. | |
| * | |
| * Note that, according to Sect. 8.1 of WCS Paper III, and | |
| * Sect. 5.2 of WCS Paper VII, the following are always inherited: | |
| * | |
| # RESTFREQ for RFRQna | |
| # RESTFRQa for RFRQna | |
| # RESTWAVa for RWAVna | |
| * | |
| * being those actually used by WCSLIB, together with the | |
| * following auxiliary keywords, many of which do not have binary | |
| * table equivalents and therefore can only be inherited: | |
| * | |
| # TIMESYS - | |
| # TREFPOS for TRPOSn | |
| # TREFDIR for TRDIRn | |
| # PLEPHEM - | |
| # TIMEUNIT - | |
| # DATEREF - | |
| # MJDREF - | |
| # MJDREFI - | |
| # MJDREFF - | |
| # JDREF - | |
| # JDREFI - | |
| # JDREFF - | |
| # TIMEOFFS - | |
| # | |
| # DATE-BEG - | |
| # DATE-AVG for DAVGn | |
| # DATE-END - | |
| # MJD-BEG - | |
| # MJD-AVG for MJDAn | |
| # MJD-END - | |
| # JEPOCH - | |
| # BEPOCH - | |
| # TSTART - | |
| # TSTOP - | |
| # XPOSURE - | |
| # TELAPSE - | |
| # | |
| # TIMSYER - | |
| # TIMRDER - | |
| # TIMEDEL - | |
| # TIMEPIXR - | |
| # | |
| # OBSGEO-X for OBSGXn | |
| # OBSGEO-Y for OBSGYn | |
| # OBSGEO-Z for OBSGZn | |
| # OBSGEO-L for OBSGLn | |
| # OBSGEO-B for OBSGBn | |
| # OBSGEO-H for OBSGHn | |
| # OBSORBIT - | |
| # | |
| # SPECSYSa for SPECna | |
| # SSYSOBSa for SOBSna | |
| # VELOSYSa for VSYSna | |
| # VSOURCEa for VSOUna ... Only if WCSHDR_VSOURCE is set. | |
| # ZSOURCEa for ZSOUna | |
| # SSYSSRCa for SSRCna | |
| # VELANGLa for VANGna | |
| * | |
| * Global image-header keywords, such as MJD-OBS, apply to all | |
| * alternate representations, and would therefore provide a | |
| * default value for all images in the header. | |
| * | |
| * This auxiliary inheritance mechanism applies to binary table | |
| * image arrays and pixel lists alike. Most of these keywords | |
| * have no default value, the exceptions being LONPOLEa and | |
| * LATPOLEa, and also RADESYSa and EQUINOXa which provide | |
| * defaults for each other. Thus one potential difficulty in | |
| * using WCSHDR_AUXIMG is that of erroneously inheriting one of | |
| * these four keywords. | |
| * | |
| * Also, beware of potential inconsistencies that may arise where, | |
| * for example, DATE-OBS is inherited, but MJD-OBS is overridden | |
| * by MJDOBn and specifies a different time. Pairs in this | |
| * category are: | |
| * | |
| = DATE-OBS/DOBSn versus MJD-OBS/MJDOBn | |
| = DATE-AVG/DAVGn versus MJD-AVG/MJDAn | |
| = RESTFRQa/RFRQna versus RESTWAVa/RWAVna | |
| = OBSGEO-[XYZ]/OBSG[XYZ]n versus OBSGEO-[LBH]/OBSG[LBH]n | |
| * | |
| * The wcsfixi() routines datfix() and obsfix() are provided to | |
| * check the consistency of these and other such pairs of | |
| * keywords. | |
| * | |
| * Unlike WCSHDR_ALLIMG, the existence of one (or all) of these | |
| * auxiliary WCS image header keywords will not by itself cause a | |
| * wcsprm struct to be created for alternate representation "a". | |
| * This is because they do not provide sufficient information to | |
| * create a non-trivial coordinate representation when used in | |
| * conjunction with the default values of those keywords that are | |
| * parameterized by axis number, such as CTYPEia. | |
| * | |
| * - WCSHDR_ALLIMG (wcsbth() only): Allow the image-header form of *all* | |
| * image header WCS keywords to provide a default value for all | |
| * image arrays in a binary table (n.b. not pixel list). This | |
| * default may be overridden by the column-specific form of the | |
| * keyword. | |
| * | |
| * For example, a keyword like CRPIXja would apply to all image | |
| * arrays in a binary table with alternate representation "a" | |
| * unless overridden by jCRPna. | |
| * | |
| * Specifically the keywords are those listed above for | |
| * WCSHDR_AUXIMG plus | |
| * | |
| # WCSAXESa for WCAXna | |
| * | |
| * which defines the coordinate dimensionality, and the following | |
| * keywords that are parameterized by axis number: | |
| * | |
| # CRPIXja for jCRPna | |
| # PCi_ja for ijPCna | |
| # CDi_ja for ijCDna | |
| # CDELTia for iCDEna | |
| # CROTAi for iCROTn | |
| # CROTAia - ... Only if WCSHDR_CROTAia is set. | |
| # CUNITia for iCUNna | |
| # CTYPEia for iCTYna | |
| # CRVALia for iCRVna | |
| # PVi_ma for iVn_ma | |
| # PSi_ma for iSn_ma | |
| # | |
| # CNAMEia for iCNAna | |
| # CRDERia for iCRDna | |
| # CSYERia for iCSYna | |
| # CZPHSia for iCZPna | |
| # CPERIia for iCPRna | |
| * | |
| * where the image-header keywords on the left provide default | |
| * values for the column specific keywords on the right. | |
| * | |
| * This full inheritance mechanism only applies to binary table | |
| * image arrays, not pixel lists, because in the latter case | |
| * there is no well-defined association between coordinate axis | |
| * number and column number (see note 9 below). | |
| * | |
| * Note that CNAMEia, CRDERia, CSYERia, and their variants are | |
| * not used by WCSLIB but are stored in the wcsprm struct as | |
| * auxiliary information. | |
| * | |
| * Note especially that at least one wcsprm struct will be | |
| * returned for each "a" found in one of the image header | |
| * keywords listed above: | |
| * | |
| * - If the image header keywords for "a" ARE NOT inherited by a | |
| * binary table, then the struct will not be associated with | |
| * any particular table column number and it is up to the user | |
| * to provide an association. | |
| * | |
| * - If the image header keywords for "a" ARE inherited by a | |
| * binary table image array, then those keywords are considered | |
| * to be "exhausted" and do not result in a separate wcsprm | |
| * struct. | |
| * | |
| * For example, to accept CD00i00j and PC00i00j and reject all other | |
| * extensions, use | |
| * | |
| = relax = WCSHDR_reject | WCSHDR_CD00i00j | WCSHDR_PC00i00j; | |
| * | |
| * The parser always treats EPOCH as subordinate to EQUINOXa if both are | |
| * present, and VSOURCEa is always subordinate to ZSOURCEa. | |
| * | |
| * Likewise, VELREF is subordinate to the formalism of WCS Paper III, see | |
| * spcaips(). | |
| * | |
| * Neither wcspih() nor wcsbth() currently recognize the AIPS-convention | |
| * keywords ALTRPIX or ALTRVAL which effectively define an alternative | |
| * representation for a spectral axis. | |
| * | |
| * 6: Depending on what flags have been set in its "relax" argument, | |
| * wcsbth() could return as many as 27027 wcsprm structs: | |
| * | |
| * - Up to 27 unattached representations derived from image header | |
| * keywords. | |
| * | |
| * - Up to 27 structs for each of up to 999 columns containing an image | |
| * arrays. | |
| * | |
| * - Up to 27 structs for a pixel list. | |
| * | |
| * Note that it is considered legitimate for a column to contain an image | |
| * array and also form part of a pixel list, and in particular that | |
| * wcsbth() does not check the TFORM keyword for a pixel list column to | |
| * check that it is scalar. | |
| * | |
| * In practice, of course, a realistic binary table header is unlikely to | |
| * contain more than a handful of images. | |
| * | |
| * In order for wcsbth() to create a wcsprm struct for a particular | |
| * coordinate representation, at least one WCS keyword that defines an | |
| * axis number must be present, either directly or by inheritance if | |
| * WCSHDR_ALLIMG is set. | |
| * | |
| * When the image header keywords for an alternate representation are | |
| * inherited by a binary table image array via WCSHDR_ALLIMG, those | |
| * keywords are considered to be "exhausted" and do not result in a | |
| * separate wcsprm struct. Otherwise they do. | |
| * | |
| * 7: Neither wcspih() nor wcsbth() check for duplicated keywords, in most | |
| * cases they accept the last encountered. | |
| * | |
| * 8: wcspih() and wcsbth() use wcsnpv() and wcsnps() (refer to the prologue | |
| * of wcs.h) to match the size of the pv[] and ps[] arrays in the wcsprm | |
| * structs to the number in the header. Consequently there are no unused | |
| * elements in the pv[] and ps[] arrays, indeed they will often be of | |
| * zero length. | |
| * | |
| * 9: The FITS WCS standard for pixel lists assumes that a pixel list | |
| * defines one and only one image, i.e. that each row of the binary table | |
| * refers to just one event, e.g. the detection of a single photon or | |
| * neutrino, for which the device "pixel" coordinates are stored in | |
| * separate scalar columns of the table. | |
| * | |
| * In the absence of a standard for pixel lists - or even an informal | |
| * description! - let alone a formal mechanism for identifying the columns | |
| * containing pixel coordinates (as opposed to pixel values or metadata | |
| * recorded at the time the photon or neutrino was detected), WCS Paper I | |
| * discusses how the WCS keywords themselves may be used to identify them. | |
| * | |
| * In practice, however, pixel lists have been used to store multiple | |
| * images. Besides not specifying how to identify columns, the pixel list | |
| * convention is also silent on the method to be used to associate table | |
| * columns with image axes. | |
| * | |
| * An additional shortcoming is the absence of a formal method for | |
| * associating global binary-table WCS keywords, such as WCSNna or MJDOBn, | |
| * with a pixel list image, whether one or several. | |
| * | |
| * In light of these uncertainties, wcsbth() simply collects all WCS | |
| * keywords for a particular pixel list coordinate representation (i.e. | |
| * the "a" value in TCTYna) into one wcsprm struct. However, these | |
| * alternates need not be associated with the same table columns and this | |
| * allows a pixel list to contain up to 27 separate images. As usual, if | |
| * one of these representations happened to contain more than two | |
| * celestial axes, for example, then an error would result when wcsset() | |
| * is invoked on it. In this case the "colsel" argument could be used to | |
| * restrict the columns used to construct the representation so that it | |
| * only contained one pair of celestial axes. | |
| * | |
| * Global, binary-table WCS keywords are considered to apply to the pixel | |
| * list image with matching alternate (e.g. the "a" value in LONPna or | |
| * EQUIna), regardless of the table columns the image occupies. In other | |
| * words, the column number is ignored (the "n" value in LONPna or | |
| * EQUIna). This also applies for global, binary-table WCS keywords that | |
| * have no alternates, such as MJDOBn and OBSGXn, which match all images | |
| * in a pixel list. Take heed that this may lead to counterintuitive | |
| * behaviour, especially where such a keyword references a column that | |
| * does not store pixel coordinates, and moreso where the pixel list | |
| * stores only a single image. In fact, as the column number, n, is | |
| * ignored for such keywords, it would make no difference even if they | |
| * referenced non-existent columns. Moreover, there is no requirement for | |
| * consistency in the column numbers used for such keywords, even for | |
| * OBSGXn, OBSGYn, and OBSGZn which are meant to define the elements of a | |
| * coordinate vector. Although it would surely be perverse to construct a | |
| * pixel list like this, such a situation may still arise in practice | |
| * where columns are deleted from a binary table. | |
| * | |
| * The situation with global, binary-table WCS keywords becomes | |
| * potentially even more confusing when image arrays and pixel list images | |
| * coexist in one binary table. In that case, a keyword such as MJDOBn | |
| * may legitimately appear multiple times with n referencing different | |
| * image arrays. Which then is the one that applies to the pixel list | |
| * images? In this implementation, it is the last instance that appears | |
| * in the header, whether or not it is also associated with an image | |
| * array. | |
| * | |
| * | |
| * wcstab() - Tabular construction routine | |
| * --------------------------------------- | |
| * wcstab() assists in filling in the information in the wcsprm struct relating | |
| * to coordinate lookup tables. | |
| * | |
| * Tabular coordinates ('TAB') present certain difficulties in that the main | |
| * components of the lookup table - the multidimensional coordinate array plus | |
| * an index vector for each dimension - are stored in a FITS binary table | |
| * extension (BINTABLE). Information required to locate these arrays is stored | |
| * in PVi_ma and PSi_ma keywords in the image header. | |
| * | |
| * wcstab() parses the PVi_ma and PSi_ma keywords associated with each 'TAB' | |
| * axis and allocates memory in the wcsprm struct for the required number of | |
| * tabprm structs. It sets as much of the tabprm struct as can be gleaned from | |
| * the image header, and also sets up an array of wtbarr structs (described in | |
| * the prologue of wtbarr.h) to assist in extracting the required arrays from | |
| * the BINTABLE extension(s). | |
| * | |
| * It is then up to the user to allocate memory for, and copy arrays from the | |
| * BINTABLE extension(s) into the tabprm structs. A CFITSIO routine, | |
| * fits_read_wcstab(), has been provided for this purpose, see getwcstab.h. | |
| * wcsset() will automatically take control of this allocated memory, in | |
| * particular causing it to be free'd by wcsfree(); the user must not attempt | |
| * to free it after wcsset() has been called. | |
| * | |
| * Note that wcspih() and wcsbth() automatically invoke wcstab() on each of the | |
| * wcsprm structs that they return. | |
| * | |
| * Given and returned: | |
| * wcs struct wcsprm* | |
| * Coordinate transformation parameters (see below). | |
| * | |
| * wcstab() sets ntab, tab, nwtb and wtb, allocating | |
| * memory for the tab and wtb arrays. This allocated | |
| * memory will be free'd automatically by wcsfree(). | |
| * | |
| * Function return value: | |
| * int Status return value: | |
| * 0: Success. | |
| * 1: Null wcsprm pointer passed. | |
| * 2: Memory allocation failed. | |
| * 3: Invalid tabular parameters. | |
| * | |
| * For returns > 1, a detailed error message is set in | |
| * wcsprm::err if enabled, see wcserr_enable(). | |
| * | |
| * | |
| * wcsidx() - Index alternate coordinate representations | |
| * ----------------------------------------------------- | |
| * wcsidx() returns an array of 27 indices for the alternate coordinate | |
| * representations in the array of wcsprm structs returned by wcspih(). For | |
| * the array returned by wcsbth() it returns indices for the unattached | |
| * (colnum == 0) representations derived from image header keywords - use | |
| * wcsbdx() for those derived from binary table image arrays or pixel lists | |
| * keywords. | |
| * | |
| * Given: | |
| * nwcs int Number of coordinate representations in the array. | |
| * | |
| * wcs const struct wcsprm** | |
| * Pointer to an array of wcsprm structs returned by | |
| * wcspih() or wcsbth(). | |
| * | |
| * Returned: | |
| * alts int[27] Index of each alternate coordinate representation in | |
| * the array: alts[0] for the primary, alts[1] for 'A', | |
| * etc., set to -1 if not present. | |
| * | |
| * For example, if there was no 'P' representation then | |
| * | |
| = alts['P'-'A'+1] == -1; | |
| * | |
| * Otherwise, the address of its wcsprm struct would be | |
| * | |
| = wcs + alts['P'-'A'+1]; | |
| * | |
| * Function return value: | |
| * int Status return value: | |
| * 0: Success. | |
| * 1: Null wcsprm pointer passed. | |
| * | |
| * | |
| * wcsbdx() - Index alternate coordinate representions | |
| * --------------------------------------------------- | |
| * wcsbdx() returns an array of 999 x 27 indices for the alternate coordinate | |
| * representions for binary table image arrays xor pixel lists in the array of | |
| * wcsprm structs returned by wcsbth(). Use wcsidx() for the unattached | |
| * representations derived from image header keywords. | |
| * | |
| * Given: | |
| * nwcs int Number of coordinate representations in the array. | |
| * | |
| * wcs const struct wcsprm** | |
| * Pointer to an array of wcsprm structs returned by | |
| * wcsbth(). | |
| * | |
| * type int Select the type of coordinate representation: | |
| * 0: binary table image arrays, | |
| * 1: pixel lists. | |
| * | |
| * Returned: | |
| * alts short[1000][28] | |
| * Index of each alternate coordinate represention in the | |
| * array: alts[col][0] for the primary, alts[col][1] for | |
| * 'A', to alts[col][26] for 'Z', where col is the | |
| * 1-relative column number, and col == 0 is used for | |
| * unattached image headers. Set to -1 if not present. | |
| * | |
| * alts[col][27] counts the number of coordinate | |
| * representations of the chosen type for each column. | |
| * | |
| * For example, if there was no 'P' represention for | |
| * column 13 then | |
| * | |
| = alts[13]['P'-'A'+1] == -1; | |
| * | |
| * Otherwise, the address of its wcsprm struct would be | |
| * | |
| = wcs + alts[13]['P'-'A'+1]; | |
| * | |
| * Function return value: | |
| * int Status return value: | |
| * 0: Success. | |
| * 1: Null wcsprm pointer passed. | |
| * | |
| * | |
| * wcsvfree() - Free the array of wcsprm structs | |
| * --------------------------------------------- | |
| * wcsvfree() frees the memory allocated by wcspih() or wcsbth() for the array | |
| * of wcsprm structs, first invoking wcsfree() on each of the array members. | |
| * | |
| * Given and returned: | |
| * nwcs int* Number of coordinate representations found; set to 0 | |
| * on return. | |
| * | |
| * wcs struct wcsprm** | |
| * Pointer to the array of wcsprm structs; set to 0x0 on | |
| * return. | |
| * | |
| * Function return value: | |
| * int Status return value: | |
| * 0: Success. | |
| * 1: Null wcsprm pointer passed. | |
| * | |
| * | |
| * wcshdo() - Write out a wcsprm struct as a FITS header | |
| * ----------------------------------------------------- | |
| * wcshdo() translates a wcsprm struct into a FITS header. If the colnum | |
| * member of the struct is non-zero then a binary table image array header will | |
| * be produced. Otherwise, if the colax[] member of the struct is set non-zero | |
| * then a pixel list header will be produced. Otherwise, a primary image or | |
| * image extension header will be produced. | |
| * | |
| * If the struct was originally constructed from a header, e.g. by wcspih(), | |
| * the output header will almost certainly differ in a number of respects: | |
| * | |
| * - The output header only contains WCS-related keywords. In particular, it | |
| * does not contain syntactically-required keywords such as SIMPLE, NAXIS, | |
| * BITPIX, or END. | |
| * | |
| * - Elements of the PCi_ja matrix will be written if and only if they differ | |
| * from the unit matrix. Thus, if the matrix is unity then no elements | |
| * will be written. | |
| * | |
| * - The redundant keywords MJDREF, JDREF, JDREFI, JDREFF, all of which | |
| * duplicate MJDREFI + MJDREFF, are never written. OBSGEO-[LBH] are not | |
| * written if OBSGEO-[XYZ] are defined. | |
| * | |
| * - Deprecated (e.g. CROTAn, RESTFREQ, VELREF, RADECSYS, EPOCH, VSOURCEa) or | |
| * non-standard usage will be translated to standard (this is partially | |
| * dependent on whether wcsfix() was applied). | |
| * | |
| * - Additional keywords such as WCSAXESa, CUNITia, LONPOLEa and LATPOLEa may | |
| * appear. | |
| * | |
| * - Quantities will be converted to the units used internally, basically SI | |
| * with the addition of degrees. | |
| * | |
| * - Floating-point quantities may be given to a different decimal precision. | |
| * | |
| * - The original keycomments will be lost, although wcshdo() tries hard to | |
| * write meaningful comments. | |
| * | |
| * - Keyword order will almost certainly be changed. | |
| * | |
| * Keywords can be translated between the image array, binary table, and pixel | |
| * lists forms by manipulating the colnum or colax[] members of the wcsprm | |
| * struct. | |
| * | |
| * Given: | |
| * ctrl int Vector of flag bits that controls the degree of | |
| * permissiveness in departing from the published WCS | |
| * standard, and also controls the formatting of | |
| * floating-point keyvalues. Set it to zero to get the | |
| * default behaviour. | |
| * | |
| * Flag bits for the degree of permissiveness: | |
| * WCSHDO_none: Recognize only FITS keywords defined by | |
| * the published WCS standard. | |
| * WCSHDO_all: Admit all recognized informal extensions | |
| * of the WCS standard. | |
| * Fine-grained control of the degree of permissiveness | |
| * is also possible as explained in the notes below. | |
| * | |
| * As for controlling floating-point formatting, by | |
| * default wcshdo() uses "%20.12G" for non-parameterized | |
| * keywords such as LONPOLEa, and attempts to make the | |
| * header more human-readable by using the same "%f" | |
| * format for all values of each of the following | |
| * parameterized keywords: CRPIXja, PCi_ja, and CDELTia | |
| * (n.b. excluding CRVALia). Each has the same field | |
| * width and precision so that the decimal points line | |
| * up. The precision, allowing for up to 15 significant | |
| * digits, is chosen so that there are no excess trailing | |
| * zeroes. A similar formatting scheme applies by | |
| * default for distortion function parameters. | |
| * | |
| * However, where the values of, for example, CDELTia | |
| * differ by many orders of magnitude, the default | |
| * formatting scheme may cause unacceptable loss of | |
| * precision for the lower-valued keyvalues. Thus the | |
| * default behaviour may be overridden: | |
| * WCSHDO_P12: Use "%20.12G" format for all floating- | |
| * point keyvalues (12 significant digits). | |
| * WCSHDO_P13: Use "%21.13G" format for all floating- | |
| * point keyvalues (13 significant digits). | |
| * WCSHDO_P14: Use "%22.14G" format for all floating- | |
| * point keyvalues (14 significant digits). | |
| * WCSHDO_P15: Use "%23.15G" format for all floating- | |
| * point keyvalues (15 significant digits). | |
| * WCSHDO_P16: Use "%24.16G" format for all floating- | |
| * point keyvalues (16 significant digits). | |
| * WCSHDO_P17: Use "%25.17G" format for all floating- | |
| * point keyvalues (17 significant digits). | |
| * If more than one of the above flags are set, the | |
| * highest number of significant digits prevails. In | |
| * addition, there is an anciliary flag: | |
| * WCSHDO_EFMT: Use "%E" format instead of the default | |
| * "%G" format above. | |
| * Note that excess trailing zeroes are stripped off the | |
| * fractional part with "%G" (which never occurs with | |
| * "%E"). Note also that the higher-precision options | |
| * eat into the keycomment area. In this regard, | |
| * WCSHDO_P14 causes minimal disruption with "%G" format, | |
| * while WCSHDO_P13 is appropriate with "%E". | |
| * | |
| * Given and returned: | |
| * wcs struct wcsprm* | |
| * Pointer to a wcsprm struct containing coordinate | |
| * transformation parameters. Will be initialized if | |
| * necessary. | |
| * | |
| * Returned: | |
| * nkeyrec int* Number of FITS header keyrecords returned in the | |
| * "header" array. | |
| * | |
| * header char** Pointer to an array of char holding the header. | |
| * Storage for the array is allocated by wcshdo() in | |
| * blocks of 2880 bytes (32 x 80-character keyrecords) | |
| * and must be free'd by the user to avoid memory leaks. | |
| * | |
| * Each keyrecord is 80 characters long and is *NOT* | |
| * null-terminated, so the first keyrecord starts at | |
| * (*header)[0], the second at (*header)[80], etc. | |
| * | |
| * Function return value: | |
| * int Status return value (associated with wcs_errmsg[]): | |
| * 0: Success. | |
| * 1: Null wcsprm pointer passed. | |
| * 2: Memory allocation failed. | |
| * 3: Linear transformation matrix is singular. | |
| * 4: Inconsistent or unrecognized coordinate axis | |
| * types. | |
| * 5: Invalid parameter value. | |
| * 6: Invalid coordinate transformation parameters. | |
| * 7: Ill-conditioned coordinate transformation | |
| * parameters. | |
| * | |
| * For returns > 1, a detailed error message is set in | |
| * wcsprm::err if enabled, see wcserr_enable(). | |
| * | |
| * Notes: | |
| * wcshdo() interprets the "relax" argument as a vector of flag bits to | |
| * provide fine-grained control over what non-standard WCS keywords to write. | |
| * The flag bits are subject to change in future and should be set by using | |
| * the preprocessor macros (see below) for the purpose. | |
| * | |
| * - WCSHDO_none: Don't use any extensions. | |
| * | |
| * - WCSHDO_all: Write all recognized extensions, equivalent to setting each | |
| * flag bit. | |
| * | |
| * - WCSHDO_safe: Write all extensions that are considered to be safe and | |
| * recommended. | |
| * | |
| * - WCSHDO_DOBSn: Write DOBSn, the column-specific analogue of DATE-OBS for | |
| * use in binary tables and pixel lists. WCS Paper III introduced | |
| * DATE-AVG and DAVGn but by an oversight DOBSn (the obvious analogy) | |
| * was never formally defined by the standard. The alternative to | |
| * using DOBSn is to write DATE-OBS which applies to the whole table. | |
| * This usage is considered to be safe and is recommended. | |
| * | |
| * - WCSHDO_TPCn_ka: WCS Paper I defined | |
| * | |
| * - TPn_ka and TCn_ka for pixel lists | |
| * | |
| * but WCS Paper II uses TPCn_ka in one example and subsequently the | |
| * errata for the WCS papers legitimized the use of | |
| * | |
| * - TPCn_ka and TCDn_ka for pixel lists | |
| * | |
| * provided that the keyword does not exceed eight characters. This | |
| * usage is considered to be safe and is recommended because of the | |
| * non-mnemonic terseness of the shorter forms. | |
| * | |
| * - WCSHDO_PVn_ma: WCS Paper I defined | |
| * | |
| * - iVn_ma and iSn_ma for bintables and | |
| * - TVn_ma and TSn_ma for pixel lists | |
| * | |
| * but WCS Paper II uses iPVn_ma and TPVn_ma in the examples and | |
| * subsequently the errata for the WCS papers legitimized the use of | |
| * | |
| * - iPVn_ma and iPSn_ma for bintables and | |
| * - TPVn_ma and TPSn_ma for pixel lists | |
| * | |
| * provided that the keyword does not exceed eight characters. This | |
| * usage is considered to be safe and is recommended because of the | |
| * non-mnemonic terseness of the shorter forms. | |
| * | |
| * - WCSHDO_CRPXna: For historical reasons WCS Paper I defined | |
| * | |
| * - jCRPXn, iCDLTn, iCUNIn, iCTYPn, and iCRVLn for bintables and | |
| * - TCRPXn, TCDLTn, TCUNIn, TCTYPn, and TCRVLn for pixel lists | |
| * | |
| * for use without an alternate version specifier. However, because | |
| * of the eight-character keyword constraint, in order to accommodate | |
| * column numbers greater than 99 WCS Paper I also defined | |
| * | |
| * - jCRPna, iCDEna, iCUNna, iCTYna and iCRVna for bintables and | |
| * - TCRPna, TCDEna, TCUNna, TCTYna and TCRVna for pixel lists | |
| * | |
| * for use with an alternate version specifier (the "a"). Like the | |
| * PC, CD, PV, and PS keywords there is an obvious tendency to | |
| * confuse these two forms for column numbers up to 99. It is very | |
| * unlikely that any parser would reject keywords in the first set | |
| * with a non-blank alternate version specifier so this usage is | |
| * considered to be safe and is recommended. | |
| * | |
| * - WCSHDO_CNAMna: WCS Papers I and III defined | |
| * | |
| * - iCNAna, iCRDna, and iCSYna for bintables and | |
| * - TCNAna, TCRDna, and TCSYna for pixel lists | |
| * | |
| * By analogy with the above, the long forms would be | |
| * | |
| * - iCNAMna, iCRDEna, and iCSYEna for bintables and | |
| * - TCNAMna, TCRDEna, and TCSYEna for pixel lists | |
| * | |
| * Note that these keywords provide auxiliary information only, none | |
| * of them are needed to compute world coordinates. This usage is | |
| * potentially unsafe and is not recommended at this time. | |
| * | |
| * - WCSHDO_WCSNna: In light of wcsbth() note 4, write WCSNna instead of | |
| * TWCSna for pixel lists. While wcsbth() treats WCSNna and TWCSna | |
| * as equivalent, other parsers may not. Consequently, this usage | |
| * is potentially unsafe and is not recommended at this time. | |
| * | |
| * | |
| * Global variable: const char *wcshdr_errmsg[] - Status return messages | |
| * --------------------------------------------------------------------- | |
| * Error messages to match the status value returned from each function. | |
| * Use wcs_errmsg[] for status returns from wcshdo(). | |
| * | |
| *===========================================================================*/ | |
| extern "C" { | |
| extern const char *wcshdr_errmsg[]; | |
| enum wcshdr_errmsg_enum { | |
| WCSHDRERR_SUCCESS = 0, /* Success. */ | |
| WCSHDRERR_NULL_POINTER = 1, /* Null wcsprm pointer passed. */ | |
| WCSHDRERR_MEMORY = 2, /* Memory allocation failed. */ | |
| WCSHDRERR_BAD_COLUMN = 3, /* Invalid column selection. */ | |
| WCSHDRERR_PARSER = 4, /* Fatal error returned by Flex | |
| parser. */ | |
| WCSHDRERR_BAD_TABULAR_PARAMS = 5 /* Invalid tabular parameters. */ | |
| }; | |
| int wcspih(char *header, int nkeyrec, int relax, int ctrl, int *nreject, | |
| int *nwcs, struct wcsprm **wcs); | |
| int wcsbth(char *header, int nkeyrec, int relax, int ctrl, int keysel, | |
| int *colsel, int *nreject, int *nwcs, struct wcsprm **wcs); | |
| int wcstab(struct wcsprm *wcs); | |
| int wcsidx(int nwcs, struct wcsprm **wcs, int alts[27]); | |
| int wcsbdx(int nwcs, struct wcsprm **wcs, int type, short alts[1000][28]); | |
| int wcsvfree(int *nwcs, struct wcsprm **wcs); | |
| int wcshdo(int ctrl, struct wcsprm *wcs, int *nkeyrec, char **header); | |
| } | |