alphaPIXArray.m

function [x,y] = alphaPIXArray(x0, y0, h0, Tmean, rot)
%
%    [x, y] = alphaPIXArray(x0, y0, h0, Tmean, rot)
%
%  creates an array of pixel sample locations for the estimation of 
%  wave direction at location [x0, y0].  Because the scales of the spatial
%  lags depend on the local wavelength, the user is asked to input the
%  mean wave period and local depth for the analysis.  Specific lag arrays 
%  and recommended scaling is mostly taken from Herbers et al, 1995.
%
%   Inputs:
%	x0,y0 	- center of the array in meters referenced to local coordinate
%		  system.  x0 cross shore, y0 along shore
%	h0 	- water depth in meters at the array center
%	Tmean 	- typical wave period of interest in seconds	
%	rot 	- array rotation in degrees (positive rotation is CCW from 
%		  a cross-shore/longshore arrangement).  Rotation is about
%		  the position [x0, y0]
%   	
%	 
%   Examples:
%      [xa1, ya1] = alphaPIXArray(200, 650, 4.5, 8.0, 10);
%      [x, y] = alphaPIXArray(400, 650, approxDuckBathy(400), 8.0, 10);
%
% See also bathyPIXArray, runupPIXArray, vbarPIXArray, dipsol
%

%  Copyright, Argus User Group, 2001
%  Authors:  Chris Chickadel, James Sulzman, Rob Holman


% set constants

% Apx/Lcen, where Apx is the aperture and Lcen is sample frequency of interest.
% the value 0.5 is a guess by Holman and Holland
kappa = 0.5; 	% this may be slightly too large (Holman, 8/01)

%The alongshore aperture divided by the cross shore aperture 
aspectRatio = 2; %Apy/Apx

%These are the cumulative lag spacings of the sample locations in meters
instPtsX = [1 9 10 13 15 20]'-1;  % cross shore Freilich from XSPECT.m 
instPtsY = [1 2 5 10 16 20 22]'-1;  % along shore

% find Lcen
k = dispsol2(h0,1/Tmean,0);
Lcen = 2*pi/k;		% k is radial wavenumber  

% find Apx, Apy, the cross-shore and longshore aperatures
Apx = Lcen*kappa;
Apy = Apx*aspectRatio;

% make inst locations
instLocX = instPtsX*Apx/max(instPtsX) - Apx/2 ;
instLocY = instPtsY*Apy/max(instPtsY) - Apy/2 ;

% make diagonal locations
diagonal = [1 1 -1 -1; -1 1 -1 1]'*[(max(instLocX)) 0; 0 (max(instLocY))]*0.5;

% make x and y vectors, then rotate 
x = [instLocX; repmat(0,size(instLocY)); diagonal(:,1)] + x0; 
y = [repmat(0,size(instLocX)); instLocY; diagonal(:,2)] + y0;
xy=[(x-x0) (y-y0)];

rot = deg2rad(rot);
xy = xy * [cos(rot) sin(rot); -sin(rot) cos(rot)];
x = xy(:,1) + x0; 
y = xy(:,2) + y0;


% Copyright by Oregon State University, 2002
% Developed through collaborative effort of the Argus Users Group
% 
% Id: alphaPIXArray.m 1.1 4/24/2 17:13:53
% Notes:  

%key pixel pixelDesign 
%comment  Creates an array of pixel sample locations for wave direction estimates 

%    This program is free software: you can redistribute it and/or
%    modify it under the terms of the GNU General Public License as
%    published by the Free Software Foundation, version 3 of the
%    License.

%    This program is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.

%    You should have received a copy of the GNU General Public License
%    along with this program.  If not, see
%                                <http://www.gnu.org/licenses/>.

% CIRN: https://coastal-imaging-research-network.github.io/