Changes between Version 3 and Version 4 of IppTools_FAQ

Timestamp:

May 19, 2009, 3:56:13 PM (17 years ago)

Author:

giebink

Comment:

--

IppTools_FAQ

@@ -8 +8 @@
 After the astrometric solution has been applied to a set of images,  you are ready to warp those images onto the sky.  To do that, you first must subdivide the sky into skycells.  Each skycell is simply a rectangular projection of some fraction of the sky onto a flat plane. The IPP defines skycells using a tesselation of triangles with common bases.  The center of each triangle defines the center of a skycell.   To create a more finely spaced grid of skycells, one can divide a triangle into three new triangles with interior lines extending from the vertices to the center.  With each level of triangle division, your skycells get smaller and the planar approximation of a spherical surface gets a little better.  Once you have defined a rectangular patch of sky with a suitable number of triangle divisions, you may chop that rectangle into smaller rectangles with divisions in the x and y directions.
 
-To define your tessellation of the sky, use the <code>skycells</code> program.  Type <code>skycells -h</code> to get a list of options.   The -level option sets the number of triangular subdivisions to use in the tessellation. If this option is omitted, <code>skycells</code> will use the SKY_DEPTH parameter from your .ptolemyrc file.   Here is an example that was used to define the FIXNS tessellation pattern, intended for the GPC1 MD field data:
+To define your tessellation of the sky, use the skycells program.  Type skycells -h to get a list of options.   The -level option sets the number of triangular subdivisions to use in the tessellation. If this option is omitted, skycells will use the SKY_DEPTH parameter from your .ptolemyrc file.   Here is an example that was used to define the FIXNS tessellation pattern, intended for the GPC1 MD field data:
 
   skycells -level 5 -scale 0.2 -nx 8 -ny 8 -fix-ns -padding 0.05
@@ -44 +44 @@
 
 {{{
-chiptool -set_label MD01.g -set_workdir /data/ipp004.0/gpc1/MD.SR -dbname PS1MD -definebyquery -ra_min 0.6 -ra_max 0.645
--decl_min -0.08 -decl_max -0.07 -exp_time_min 200 -filter g.00000 -simple
+chiptool -set_label MD01.g -set_workdir /data/ipp004.0/gpc1/MD.SR -dbname PS1MD -definebyquery -ra_min 0.6 -ra_max 
+0.645 -decl_min -0.08 -decl_max -0.07 -exp_time_min 200 -filter g.00000 -simple
 }}}
 
@@ -79 +79 @@
 -min_num : you may only want to execute the stack when it has a certain number of contributing skyfiles.  Specifying the -min_num option tells stacktool to return an empty set unless it has at least min_num skyfiles. 
 
--min_new<  : ??
+-min_new  : ??
 
 -min_frac : ??