Transforms a list of images by resampling
’s coordinate limits. Many images can be
resampled with a single invocation of TRANNDF, but it is the user’s responsibility to ensure that they
are resampled into the same coordinate system if they are subsequently to be combined or compared
on a pixel-by-pixel basis.
Images processed by CCDPACK are resampled in one of two ways, depending on the value of the USEWCS parameter.
If USEWCS is TRUE then they are resampled from their Pixel coordinates into their Current attached
coordinate system (this is the default). Since the resampling means that a 1 x 1 square in the Current
coordinates will represent one pixel in the output image, the Current coordinate system
must be of an appropriate size (so for instance resampling into SKY coordinates is not
suitable because they have units of radians). The Current coordinate system will typically
have been added by the CCDPACK REGISTER or WCSREG applications, and be labelled
’CCD_REG’ or ’CCD_WCSREG’ accordingly - if it has another label (domain) a warning will be
issued but resampling will proceed. A copy of the original PIXEL coordinate system will
be retained in the WCS component of the new image under the name CCD_OLDPIXEL;
this can be useful for transforming positions back into the pre-transformation coordinate
system.
If USEWCS is set to FALSE, then the resampling will take place according to the TRANSFORM structure stored in the .MORE.CCDPACK extension of the file. This option exists chiefly for compatibility with older versions of CCDPACK.
"SPECIFY" then this parameter specifies the lower pixel-index bounds of all the output images.
The number of values should equal the maximum number of dimensions of the input
images. The suggested defaults are the lower bounds generated by the SHAPE="AUTO"
option for the first image. These bounds are probably small enough to ensure that all the
transformed data (of the first image) will appear in the output image. [Dynamic default] If the logging system has been initialised using CCDSETUP then the value specified there will be
used. Otherwise, the default is "CCDPACK.LOG". [CCDPACK.LOG]
TERMINAL – Send output to the terminal only
LOGFILE – Send output to the logfile only (see the LOGFILE parameter)
BOTH – Send output to both the terminal and the logfile
NEITHER – Produce no output at all
If the logging system has been initialised using CCDSETUP then the value specified there will be
used. Otherwise, the default is "BOTH". [BOTH]
"NEAREST" for nearest-neighbour, and "LININT" for linear interpolation. [NEAREST] "∗"
which means call each of the output images the same name as the corresponding input images.
So:
IN >
∗
OUT >
∗
signifies that all the images in the current directory should be used and the output images should have the same names. Other types of modification can also be used, such as,
OUT > ∗-TRN
which means call the output images the same as the input images but add -TRN to the end of the names. Replacement of a specified string with another in the output file names can also be used:
OUT > ∗|RAW|RES|
this replaces the string RAW with RES in any of the output names.
"AUTO", "SAME", "SPECIFY". With the meanings.
AUTO – automatically determine the bounds of the output images such that all of the input data appears. This is achieved by transforming test points along the current bounds so assumes that the transformation will behave reasonably.
SAME – set the output image bounds to those of the corresponding input images.
SPECIFY – you will specify a single set of bounds for all the output images. (See the LBOUND and UBOUND parameters.) [AUTO]
"SPECIFY" then this parameter specifies the upper
pixel-index bounds of all the output images. The number of values should equal the maximum
number of dimensions of the input images. The suggested defaults are the upper bounds
generated by the SHAPE="AUTO" option for the first image. These bounds are probably
large enough to ensure that all the transformed data (of the first image) will appear in
the output image. [Dynamic default] ’s WCS extension
as an attached coordinate system. If FALSE then the transformation is either stored as a
TRN structure in the image’s CCDPACK extension (.MORE.CCDPACK.TRANSFORM), or
is supplied by the user (see the INEXT parameter). [TRUE] ’∗’
’∗-resamp’
reset ’a119∗’
’∗s’ inext=false
transform=proj.merc shape=bounds lbound=’[1,-20]’ ubound=’[256,172]’ "current" value is the value assigned on the last run of the application. If
the application has not been run then the "intrinsic" defaults, as shown in the parameter help, apply.
The exceptions to this rule are: LBOUND – always uses a dynamic default
UBOUND – always uses a dynamic default
TITLE – always "Output from TRANNDF"
Retaining parameter values has the advantage of allowing you to define the default behaviour of the application but does mean that additional care needs to be taken when using the application after a break of sometime. The intrinsic default behaviour of the application may be restored by using the RESET keyword on the command line.
Certain parameters (LOGTO and LOGFILE) have global values. These global values will always take precedence, except when an assignment is made on the command line. Global values may be set and reset using the CCDSETUP and CCDCLEAR commands.
Flux conservation can only be applied to constant-determinant or linear transformations. It is currently impossible to tell whether an AST Mapping is linear, but in the expectation that it is (most of them are, and most of the rest very nearly are), it is turned on, without a warning, by default.
The NDF components are processed by this application as follows:
AXES, LABEL, UNITS, HISTORY, and extensions are merely propagated.
QUALITY is not derived from the input NDF for a linearly interpolated NDF. The DATA and VARIANCE arrays are resampled.
If USEWCS is TRUE, then the NDF WCS component is updated and propagated.
Bad pixels, including automatic quality masking, are supported.
All non-complex numeric data types are supported.
There can be an arbitrary number of NDF dimensions.