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author | hack <hack@stsci.edu> | 2012-09-19 12:40:47 -0400 |
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committer | hack <hack@stsci.edu> | 2012-09-19 12:40:47 -0400 |
commit | 8ea0a2ba37cdfdc973f3bea888c97af549eebadf (patch) | |
tree | d3e510e1d26aa325a14c285203a86a7d55a216c9 /doc | |
parent | e1d0d1818520a0ea98e25ceaba432e30fe4fb429 (diff) | |
download | stwcs_hcf-8ea0a2ba37cdfdc973f3bea888c97af549eebadf.tar.gz |
Replaced all references to Paper IV with 'FITS Distortion Paper' in docs, as Paper IV now refers to Time coordinates.
git-svn-id: http://svn.stsci.edu/svn/ssb/stsci_python/stsci_python/trunk/stwcs@19557 fe389314-cf27-0410-b35b-8c050e845b92
Diffstat (limited to 'doc')
-rw-r--r-- | doc/source/fits_conventions.rst | 28 | ||||
-rw-r--r-- | doc/source/headerlet_def.rst | 4 | ||||
-rw-r--r-- | doc/source/npol.rst | 2 | ||||
-rw-r--r-- | doc/source/updatewcs.rst | 2 |
4 files changed, 18 insertions, 18 deletions
diff --git a/doc/source/fits_conventions.rst b/doc/source/fits_conventions.rst index 0938857..803070f 100644 --- a/doc/source/fits_conventions.rst +++ b/doc/source/fits_conventions.rst @@ -112,18 +112,18 @@ available. The SIP convention gets applied to the input pixel positions by apply higher-order coefficients A_i_j, B_i_j, then by applying the CD matrix and adding the CRVAL position to get the final world coordinates. -This convention was created from the original form of the FITS Paper IV standards, but the -Paper IV proposal since changed to use a different set of keywords and conventions. +This convention was created from the original form of the FITS Distortion Paper standards, but the +FITS Distortion Paper proposal since changed to use a different set of keywords and conventions. A sample ACS/WFC SCI header can be found in :ref:`Appendix1` to illustrate how these keywords actually get populated for an image. The current implementation does not take advantage of the A_DMAX, B_DMAX, SIPREFi or SIPSCLi keywords, so these keywords are not written out to the SCI header. -Paper IV Proposal -================= +FITS Distortion Proposal +========================= -The current Paper IV conventions [PaperIV]_ provide a mechanism for specifying either a lookup table +The current FITS Distortion Paper conventions [DistortionPaper]_ provide a mechanism for specifying either a lookup table or polynomial model for the distortion of each axis. The standard states in Section 2.1: ``Note that the prior distortion functions,, operate on pixel coordinates (i.e. p @@ -135,7 +135,7 @@ we do not allow the possibility of`` q'_{3} = q_{3} + \delta_{q_{3}}(q'_{1},q'_{2}) -The keywords used for describing these corrections use the syntax given in Table 2 of Paper IV. +The keywords used for describing these corrections use the syntax given in Table 2 of the FITS Distortion Paper. For our purposes, the keywords of interest are those related to lookup tables; namely, :: @@ -148,9 +148,9 @@ This syntax only provides the option to specify one correction at a time for eac axis of the image. This precludes being able to use this convention to specify both a lookup table and a polynomial model at the same time for the same axis. It does not state what should be done if the polynomial has been specified using a different -convention, for example, the SIP convention. Thus, SIP and Paper IV should not be +convention, for example, the SIP convention. Thus, SIP and FITS Distortion Paper should not be seen as mutually exclusive. In fact, they may work together rather naturally since the -SIP and Paper IV conventions both assume the corrections will work on the input pixel +SIP and FITS Distortion Paper conventions both assume the corrections will work on the input pixel and add to the output frame. The sample header in :ref:`Appendix1` shows how these keywords get populated for @@ -204,7 +204,7 @@ The last element of the distortion which remains to be described is the fixed co position and the output of this correction is to be used as input to the polynomial and non-polynomial distortion corrections. -The adopted implementation is based on Paper IV Lookup Table convention. It is assumed +The adopted implementation is based on the FITS Distortion Paper lookup table convention. It is assumed that the detector to image correction is the same for all chips but it can be extended to arbitrary number of chips and extensions if necessary. @@ -269,8 +269,8 @@ the original input pixel position. Merging Of The Conventions ========================== -The full implementation of all these elements ends up merging the SIP, DET2IM and Paper IV -conventions to create a new version of the figure from Paper IV which illustrates the conversion +The full implementation of all these elements ends up merging the SIP, DET2IM and FITS Distortion Paper +conventions to create a new version of the figure from the FITS Distortion Paper which illustrates the conversion of detector coordinates to world coordinates. This implementation works in the following way: #. Apply detector to image correction (DET2IM) to input pixel values @@ -316,7 +316,7 @@ where through the DET2IM convention * u',v' are the DET2IM-corrected coordinates relative to CRPIX1,CRPIX2 * :math:`LT_{x}, LT_{y}` is the residual distortion in the lookup tables - written to the header using the Paper IV lookup table convention + written to the header using the FITS Distortion Paper lookup table convention * A, B are the SIP coefficients specified using the SIP convention These equations do not take into account the deprojection from the tangent plane to @@ -327,7 +327,7 @@ the CTYPE keyword. Coordinate Transformation Pipeline -.. [PaperIV] Calabretta M. R., Valdes F. G., Greisen E. W., and Allen S. L., 2004, +.. [DistortionPaper] Calabretta M. R., Valdes F. G., Greisen E. W., and Allen S. L., 2004, "Representations of distortions in FITS world coordinate systems",[cited 2012 Sept 18], Available from: http://www.atnf.csiro.au/people/mcalabre/WCS/dcs_20040422.pdf @@ -346,7 +346,7 @@ this header includes the keywords referring to additional distortion corrections related to non-polynomial corrections from the NPOLFILE and to column-width corrections from the D2IMFILE. This sample illustrates how all three corrections can be specified at the same time in a FITS header using our rules for combining the SIP WCS convention and -FITS WCS Paper IV proposed syntax, while also using FITS WCS Paper I alternate WCS +FITS Distortion Paper proposed syntax, while also using FITS WCS Paper I alternate WCS standards to maintain a record of the WCS information prior to being updated/recomputed to use the new reference information. The old WCS gets stored using WCS key 'O' and 'WCSNAMEO' = 'OPUS' to indicate it was originally computed by OPUS, the HST pipeline system. diff --git a/doc/source/headerlet_def.rst b/doc/source/headerlet_def.rst index 9d4afd0..c05c02c 100644 --- a/doc/source/headerlet_def.rst +++ b/doc/source/headerlet_def.rst @@ -35,7 +35,7 @@ The WCS information in the FLT images has been updated to include the full disto * **SIP coefficients**: A_*_* and B_*_*, A_ORDER, B_ORDER, OCX10, OCX11, OCY10, and OCY11 keywords * **NPOL file**: if an NPOLFILE has been specified for the image, - CPDIS and DP record-value keywords to point to WCSDVARR extensions (Paper IV convention) + CPDIS and DP record-value keywords to point to WCSDVARR extensions (FITS Distortion Paper convention) * **Column correction file**: if a D2IMFILE has been specified for use with the image, the D2IMEXT and D2IMERR keywords signify the use of a D2IM file extension * **WCSDVARR extensions**: 2 extensions for each chip with lookup tables containing @@ -111,7 +111,7 @@ The `headerlet` defined above serves as the default headerlet for any image prov * **Required**: A primary header with specific keywords which specify a unique headerlet name and a targeted image. * **Required**: An SIPWCS extension for each chip which contains the linear WCS as well as any distortion model supported by FITS (for example, updated SIP coefficients) - * **Optional**: Any additional look up tables with refinements to the polynomial solutions in the SIPWCS extension. Any such extensions should be linked to the SIPWCS extension using the same Paper IV conventions used for the NPOLFILE tables. + * **Optional**: Any additional look up tables with refinements to the polynomial solutions in the SIPWCS extension. Any such extensions should be linked to the SIPWCS extension using the same FITS Distortion Paper conventions used for the NPOLFILE tables. * **Optional**: Detector to image correction array as a separate extension if needed. This custom `headerlet` should be capable of being used to overwrite the existing SCI header WCS keywords to provide a FITS-supported WCS. diff --git a/doc/source/npol.rst b/doc/source/npol.rst index 89c3a67..b398be1 100644 --- a/doc/source/npol.rst +++ b/doc/source/npol.rst @@ -37,7 +37,7 @@ New representation - look-up tables The fine scale distortions represented in the ``DGEO`` images can be stored in smaller look-up tables without significant loss of information. These look-up tables follow the conventions -in WCS Paper IV [2]_. Record-valued keywords are used to map an image in the science extension +in the WCS FITS Distortion Paper [2]_. Record-valued keywords are used to map an image in the science extension to a distortion array in the ``WCSDVAR extension``. This new type of FITS keywords has been implemented in PyFITS and is fully described in [2]_. Specifically, ``DPj.EXTVER`` in the science extension header maps the science image to the correct ``WCSDVAR`` extension. The dimensionality diff --git a/doc/source/updatewcs.rst b/doc/source/updatewcs.rst index e04a0fe..f01a9ed 100644 --- a/doc/source/updatewcs.rst +++ b/doc/source/updatewcs.rst @@ -57,7 +57,7 @@ where * x', y' are the initial coordinates x,y with the 68th column correction applied through the DET2IM convention * u',v' are the DET2IM-corrected coordinates relative to CRPIX1,CRPIX2 -* LT<sub>x</sub>, LT<sub>y</sub> is the residual distortion in the lookup tables written to the header using the Paper IV lookup table convention +* LT<sub>x</sub>, LT<sub>y</sub> is the residual distortion in the lookup tables written to the header using the FITS Distortion Paper lookup table convention * A, B are the SIP coefficients specified using the SIP convention .. toctree:: |