Changeset 26542 for branches/eam_branches/20091201/psphot/doc/stack.txt

Timestamp:

Jan 7, 2010, 5:07:54 PM (17 years ago)

Author:

eugene

Message:

upgrade psphot functions to work in the stack context (see doc/stack.txt)

File:

• branches/eam_branches/20091201/psphot/doc/stack.txt (modified) (1 diff)

branches/eam_branches/20091201/psphot/doc/stack.txt

@@ +1 @@
+
+20100107 : updates for stack processing
+
+  I am building a new version of psphot that operates on a set of
+  images (eg, multi-filter or multi-epoch).  The assumptions are:
+
+  * each input image represents the same sky pixels : they are warped to a common frame.
+  * each image has been previously processed, with the background
+    subtracted (and the psf model determined?)
+  * all planes are / can be loaded into memory at once (otherwise I
+    need to add a lot of I/O layers)
+
+  psphot currently expects the pmFPAfile of interest to be available in
+  config->files with the name PSPHOT.INPUT.  To update the code for
+  stacks, I am extending this concept with the pmFPAfileSelectSingle
+  API: config->files may contain multiple PSPHOT.INPUT entries, and
+  functions which access this file / these files need to specify
+  *which* image they want.  The number of PSPHOT.INPUT entries is
+  saved in config->arguments as PSPHOT.INPUT.NUM (this can be
+  generated from the filerule PSPHOT.INPUT for extension).
+
+  As a result, we need a number of wrapper functions which loop over
+  all PSPHOT.INPUT.NUM entries and perform a particular operation on
+  one of the entries.  Here are the functions which I have modified
+  in this way (function -> child)
+
+  * psphotAddPhotcode -> psphotAddPhotcodeReadout
+    * note that the photcode is now saved on readout->analysis
+  * psphotSetMaskAndVariance -> psphotSetMaskAndVarianceReadout
+  * psphotModelBackground -> psphotModelBackgroundReadoutFileIndex
+  * psphotSubtractBackground -> psphotSubtractBackgroundReadout
+
+  side notes on 
+  
+  * psphotModelBackground vs psphotBackgroundModel : I've renamed
+    psphotBackgroundModel (used only by ppStack for now) to
+    psphotModelBackgroundReadoutNoFile.  I've also named the
+    single-readout version used by psphotModelBackground to
+    psphotModelBackgroundReadoutFileIndex.  These two functions do the
+    same thing, but psphotModelBackgroundReadoutNoFile does not save
+    a pmFPAfile on config->files
+
 
 20090606 : design notes on the multi-image photometry analysis