queryDisc

Find all pixels whose centers are within a specified disc

Contents

Syntax

pix = queryDisc(nSide,c0,r,'Param1',Value1,...)

Input Arguments

nSide     HEALPix resolution parameter
c0        disc center. May be specified as a pixel number, spherical
          coordinate location [theta, phi] in rads, or as a cartesian
          unit vector [x;y;z].
r         disc radius (radians)
Param     Value
'nest'    pixels are returned using nested indexing (true | {false})

Return Arguments

pix      list of pixels in disc

Example

nSide=32;
% Pixels within pi/10 radians of north pole
pix = queryDisc(nSide,[0;0;1],pi/10);
numel(pix)
nSide2nPix(nSide)*((pi/10)/(4*pi))
% Pixels within pi/10 radians of south pole
pix = queryDisc(nSide,[0;0;-1],pi/10);
numel(pix)
% Pixels within pi/10 radians of 0 long, lat
pix = queryDisc(nSide,[1;0;0],pi/10);
numel(pix)
ans =

   312


ans =

  307.2000


ans =

   312


ans =

   302

See also

queryPolygon, queryStrip, queryTriangle

Requires

pix2vec, ang2vec, angDist

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