template_pixel_nest & template_pixel_ring
These IDL facilities provide the index of the template pixel associated with a given
HEALPix pixel, for a resolution parameter
Nside.
Location in HEALPix directory tree: src/idl/toolkit/template_pixel_nest.pro src/idl/toolkit/template_pixel_ring.pro
FORMAT
QUALIFIERS
-
Nside
- (IN, scalar) the HEALPix
Nside parameter.
-
Pixel_Nest
- (IN, scalar or vector) NESTED scheme pixel identification number(s) over the range {0,
12Nside2-1}.
-
Pixel_Ring
- (IN, scalar or vector) RING scheme pixel identification number(s) over the
range {0,
12Nside2-1}.
-
Template
- (OUT, scalar or vector) identification number(s) of the
template matching in shape the pixel(s) provided (the numbering
scheme of the pixel templates is the same for both routines).
-
Reflexion
- (OUT, scalar or vector) in {0, 3} encodes the transformation(s) to
apply to each pixel provided to match exactly in
shape and position its respective template. 0: rotation around the polar axis only,
1: rotation + East-West swap (ie, reflexion around meridian),
2: rotation + North-South swap (ie, reflexion around
Equator), 3: rotation + East-West and North-South swaps
DESCRIPTION
template_pixel_nest & template_pixel_ring provide the index of the template pixel associated with a given
HEALPix pixel, for a resolution parameter
Nside.
Any pixel can be matched in shape
to a single of these templates by a combination of a rotation around the polar axis with
reflexion(s) around a meridian and/or the equator.
The template pixels are all located in the Northern Hemisphere, or on the
Equator.
They are chosen to have their center located at
They are numbered continuously from 0, starting at the North Pole, with the index
increasing in
, and then increasing for decreasing z.
EXAMPLE:
template_pixel_ring, 256, 500000, template, reflexion
Returns in template the index of the template pixel (16663) whose shape matches
that of the pixel #500000 for
Nside=256. Upon return reflexion will
contain 2, meaning that the template must be reflected around a meridian and
around the equator (and then rotated around the polar axis) in order to match
the pixel.
RELATED ROUTINES
This section lists the routines related to template_pixel_nest & template_pixel_ring
-
nside2templates
- returns the
number of template pixel shapes available for a given
Nside.
-
same_shape_pixels_ring
-
same_shape_pixels_nest
- return
the ordered list of pixels having the same shape as a given pixel template
Version 3.50, 2018-12-10