ISOCAM Interactive Analysis User's Manual Version 5.0 - ISO - ESA

274 CHAPTER 21. USING SLICE WITHIN CIA
A detailed description of the algorithms in SLICE can be found in M. A. Miville-Deschênes’
paper (2000, A&A 146, 519), while the package has it own user’s manual available at in the doc
directory of the SLICE delivery.
An important note for SLICE V1.2: Although optical distortion has been computed
for all ISOCAM configurations and can be corrected in CIA, SLICE V1.2 incorporates an older
correction scheme. As a result only the most widely used optical configurations can be corrected
for distortion in SLICE. This limitation is known to M. A. Miville-Deschênes and should be
uplifted in subsequent releases of SLICE.
21.3 Organization of data in SLICE
In CIA, data are either stored in hidden structures (the SCD, SSCD, SAD, SSAD) that you
access through pointers, or in standard IDL structures (the so-called PDS) that you manipulate
directly.
In SLICE this is different: data are stored in IDL variables (i.e. you can manipulate them
directly) but these also belong to common blocks that are accessed by SLICE routines. As a
result, their names are defined once and for all, and you cannot use them for other purposes.
This is why SLICE is not loaded by default when you start CIA.
Although you can do it in SLICE, we assume here that dark correction, de-glitching and
transient correction are performed in CIA. You will generally start the SLICE processing after
these three steps, i.e. where, in a more standard reduction session, you would have made the
flat-field correction.
To start SLICE, the first step is to initialize its common blocks as well as place its directories
in your IDL path. This is simply done with:
CIA> @cia slice init
This creates variables that will be used to store your data, any variable with the same
name is therefore erased. Their names and content are listed in Table 21.1.
You need now to transfer your data into these variables. This is done with the CIA routine
raster2slice, therefore type:
CIA> raster2slice,data
The next section will describe the processing that you can do in SLICE. For completeness
reasons, let us see here also how to transfer data back from SLICE into a CIA structure. This
is also very simple as you just have to type:
CIA> new raster = slice2raster()
This function requires no argument as all the required data are already in the SLICE
commons. You will see that the content of the output raster structure is different from that
of the input one. In particular, the raster field that contains the final map is generally larger.
This is due to the SLICE convention of only building maps with North up and East left (the
astronomical convention). This in general results in larger raster maps. Note however that
this new raster structure is fully compatible with CIA. In particular it can be examined with
isocont.