same_shape_pixels_nest & same_shape_pixels_ring
These IDL facilities provide the ordered list of all HEALPix pixels having the same shape
as a given template, for a resolution parameter
Nside.
Location in HEALPix directory tree: src/idl/toolkit/same_shape_pixels_nest.pro src/idl/toolkit/same_shape_pixels_ring.pro
FORMAT
QUALIFIERS
-
Nside
- (IN, scalar) the HEALPix
Nside parameter.
-
Template
- (IN, scalar) identification number of the
template (this number is independent of the numbering scheme considered).
-
List_Pixels_Nest
- (OUT, vector) ordered list of NESTED scheme identification numbers
for all pixels having the same shape as the template provided
-
List_Pixels_Ring
- (OUT, vector) ordered list of RING scheme identification numbers
for all pixels having the same shape as the template provided
-
Reflexion
- (OUT, OPTIONAL, vector) in {0, 3} encodes the transformation(s) to
apply to each of the returned pixels to match exactly in
shape and position the template provided. 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
KEYWORDS
-
NREPLICATIONS
- (OUT, OPTIONAL, scalar) number of pixels having the same shape as
the template. It is also the length of the vectors List_Pixel_Nest,
List_Pixel_Ring and Reflexion. It is either 8, 16, 4
Nside or
8
Nside.
DESCRIPTION
same_shape_pixels_nest & same_shape_pixels_ring provide the ordered list of all HEALPix pixels having the same shape
as a given template, for a resolution parameter
Nside. Depending on the
template considered the number of such pixels is either 8, 16, 4
Nside or
8
Nside. The template pixels are all located in the Northern Hemisphere, or on the
Equator.
They are chosen to have their center located at
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(7) |
They are numbered continuously from 0, starting at the North Pole, with the index
increasing in , and then increasing for decreasing z.
EXAMPLE:
same_shape_pixels_ring, 256, 1234, list_pixels, reflexion, nrep=np
Returns in list_pixels the RING-scheme index of the all the pixels having
the same shape as the template #1234 for
Nside=256. Upon return reflexion will
contain the reflexions to apply to each pixel returned to match the template,
and np will contain the number of pixels having that same shape (16 in that case).
RELATED ROUTINES
This section lists the routines related to same_shape_pixels_nest & same_shape_pixels_ring
-
nside2templates
- returns the
number of template pixel shapes available for a given
Nside.
-
template_pixel_ring
-
template_pixel_nest
- return
the template shape matching the pixel provided
Version 3.83, 2024-11-13