corners

Find pixel corners

Contents

Syntax

xyz = corners(nSide,nPix,'Param1',Value1,...);

Input Arguments

nSide    HEALPix resolution parameter
nPix     (optional) pixel list. Default all pixels.
Param    Value
'nest'   nested indexing (true | {false})

Return Arguments

xyz    size(nPix) cell array of [3,1] cartesian vector pixel corner
       locations

Example:

nSide = 2^2;
% Corners for all 48 nSide=4 pixels in ring-indexed order
xyzR = corners(nSide);
size(xyzR)
xyzR{1}
xyzR{end-1}

nPix = randi(nSide2nPix(nSide), 3, 4);
% Corners for an assortment of pixels in nested index order
xyzN = corners(nSide,nPix,'nest',true);
% Convert to pixel list to ring indexing
r = xyzR{nest2ring(nSide,nPix(2,3))}
% Corners for same pixels requested via ring indexing
n = xyzN{2,3}
% Compare
all(r == n)
ans =

     1   192


ans =

         0    0.2031    0.2826    0.0000
         0         0    0.2826    0.2031
    1.0000    0.9792    0.9167    0.9792


ans =

   -0.2826   -0.2031         0   -0.0000
   -0.2826    0.0000         0   -0.2031
   -0.9167   -0.9792   -1.0000   -0.9792


r =

    0.5478    0.7071    0.5478    0.3827
    0.8198    0.7071    0.8198    0.9239
    0.1667         0   -0.1667         0


n =

    0.5478    0.7071    0.5478    0.3827
    0.8198    0.7071    0.8198    0.9239
    0.1667         0   -0.1667         0


ans =

     1     1     1     1

Copyright 2010-2011 Lee Samuel Finn. Terms of Use.