NAME

       mProjectPP - Re-project FITS images

SYNOPSIS

       mProjectPP  [-z  factor]  [-d  level]  [-b  border]  [-s  statusfile]  [-o altout.hdr] [-i
       altin.hdr] [-h hdu] [-x scale]  [-w  weightfile]  [-t  threshold]  [-X]  in.fits  out.fits
       template.hdr

DESCRIPTION

       mProjectPP  reprojects  a  single  image  to the scale defined in an alternate FITS header
       template generated (usually) by mTANhdr. The  program  produces  a  pair  of  images:  the
       reprojected image and an "area" image consisting of the fraction input pixel sky area that
       went into each output pixel.  This area image goes through all the  subsequent  processing
       that the reprojected image does, allowing it to be properly coadded at the end.

       mProjectPP performs a plane-to-plane transform on the input image, and is an adaptation of
       the Mopex algorithm and developed in collaboration with the  Spitzer Space  Telescope.  It
       provides  a  speed  increase  of  approximately  a  factor  of 30 over the general-purpose
       mProject. However, mProjectPP is only suitable for projections which can  be  approximated
       by  tangent-plane  projections  (TAN, SIN, ZEA, STG, ARC), and is therefore not suited for
       images covering large portions of the sky. Also note that it  does  not  directly  support
       changes  in  coordinate  system  (i.e.  equatorial  to galactic coordinates), though these
       changes can be facilitated by the use of an alternate header.

       One situation that has happened often enough to warrant special note:  It is  possible  to
       define  a  FITS  header  with the reference location off the image.  In particular, people
       often reference cylindrical projections (e.g., CAR, CEA) to location  (0.,0.)  (e.g.,  the
       Galactic  center).   This  is  not  wrong in itself but does lead to extremely large pixel
       offsets (e.g., in the hundreds of thousands).  Related to this, if you  extract  a  header
       from  an  image with large offsets of this type, it is unlikely that you can simply change
       projection types without also adjusting the reference location/offsets.  Most likely,  you
       will end up with the reproject data all being off-scale.

OPTIONS

       -z factor
              Processing  is  done  utilizing  the  drizzle algorithm. factor is a floating point
              number; recommended drizzle factors are from 0.5 to 1.

       -d level
              Causes additional debugging information to be printed to stdout.  Valid levels  are
              1-5; for levels greater than 1, it's recommended to redirect the output into a text
              file.

       -b border
              Ignores border pixels around the image edge when performing calculations.

       -s statusfile
              Output and errors are written to statusfile instead of being written to stdout.

       -[i|o] alternate.hdr
              Specifies an alternate FITS header  for  use  in  mProjectPP  calculations,  allows
              substitution of psuedo-TAN headers created by mTANHdr.

       -h hdu Specify the FITS extension to re-project if the FITS image is multi-extension.

       -x scale
              Multiple  the  pixel  values  by scale when reprojecting.  For instance, each 2MASS
              image has a  different  scale  factor  (very  near  1.0)  to  correct  for  varying
              magnitude-zero points.

       -w weightfile
              Path to a weight map to be used when reading values from the input image.

       -t threshold
              If  using  a  weight  image;  only use those pixels where the weight value is above
              threshold.

       -X     Reproject the whole image even if part of it is  outside  the  region  of  interest
              (don't crop while re-projecting).

ARGUMENTS

       in.fits
              Input FITS file to be reprojected.

       out.fits
              Path to output FITS file to be created.

       template.hdr
              FITS header template to be used in generation of output FITS

RESULT

       Two files are created as output: the reprojected FITS file (out.fits), and an "area" image
       (out_area.fits). See the image reprojection algorithm for more information.

MESSAGES

       OK     [struct stat="OK", time=seconds]

       ERROR  Drizzle factor string (string) cannot be interpreted as a real number

       ERROR  Cannot open status file: statusfile

       ERROR  Weight threshold string (threshold) cannot be interpreted as a real number

       ERROR  Flux scale string (scale) cannot be interpreted as a real number

       ERROR  Border value string (string) cannot be interprted as an integer or a set of polygon
              vertices

       ERROR  Border value (value) must be greater than or equal to zero

       ERROR  HDU value (hdu) must be a non-negative integer

       ERROR  Could not set up plane-to-plane transform.  Check for compliant headers.

       ERROR  No overlap

       ERROR  Not enough memory for output data image array

       ERROR  Not enough memory for output area image array

       ERROR  Output wcsinit() failed.

       ERROR  Input wcsinit() failed.

       ERROR  Input and output must be in the same coordinate system for fast reprojection

       ERROR  All pixels are blank

       ERROR  Input  image  projection  (projection)  must  be TAN, SIN, ZEA, STG or ARC for fast
              reprojection

       ERROR  Output image projection (projection) must be TAN, SIN, ZEA, STG  or  ARC  for  fast
              reprojection

       ERROR  Template file [template.hdr] not found

       ERROR  Image file in.fits is missing or invalid FITS

       ERROR  Weight file weightfile is missing or invalid FITS

       ERROR  FITS library error

EXAMPLES

       $ mProjectPP rawdir/real_orig.fits projdir/base_unity.fits templates/galactic_orig.txt
              [struct stat="OK", time=14]

BUGS

       The drizzle algorithm has been implemented but has not been tested in this release.

       If  a  header  template  contains  carriage  returns  (i.e., created/modified on a Windows
       machine), the cfitsio library will be unable to read it properly, resulting in the  error:
       [struct stat="ERROR", status=207, msg="illegal character in keyword"]

       It  is  best  for the background correction algorithms if the area described in the header
       template completely encloses all of the input images in their entirety. If parts of  input
       images  are  "chopped  off"  by  the  header  template,  the background correction will be
       affected. We recommend you use an expanded header  for  the  reprojection  and  background
       modeling  steps, returning to the originally desired header size for the final coaddition.
       The default background matching assumes that there are no non-linear background variations
       in  the  individual  images  (and  therefore  in the overlap differences). If there is any
       uncertainty in this regard, it is safer to turn on the "level  only"  background  matching
       (the "-l" flag in mBgModel.

       mProjectPP  is  only suitable for use on projections which can be approximated by tangent-
       plane projections (TAN, SIN, ZEA, STG, ARC),  and  is  therefore  not  suited  for  images
       covering large portions of the sky. Also note that it does not directly support changes in
       coordinate system (i.e. equatorial to galactic coordinates), though these changes  can  be
       facilitated by the use of an alternate header.

COPYRIGHT

       2001-2015 California Institute of Technology, Pasadena, California

       If  your  research  uses  Montage,  please  include  the  following acknowledgement: "This
       research made use of Montage. It is funded by the National Science Foundation under  Grant
       Number  ACI-1440620,  and  was  previously  funded  by  the National Aeronautics and Space
       Administration's Earth Science Technology Office, Computation Technologies Project,  under
       Cooperative  Agreement  Number  NCC5-626  between  NASA  and  the  California Institute of
       Technology."

       The Montage distribution includes an adaptation of the MOPEX algorithm  developed  at  the
       Spitzer Science Center.