function plotfan(fn,settings,plottype);
% PLOTFAN - Plot Imagenex imaging sonar data
% plotfan(fn,rot,settings,plottype);
%
% fn = file name
% imagedata = the image as [angle, point]
% headangle = the head position in degrees
% prange = profile range in cm
% metadata:
% settings.SectorSweep 
% settings.StepSize 
% settings.DataPoints 
% settings.Height 
% settings.datayear
% plottype = | 'polar' | 'prange' |

% Last revised by Chris Sherwood, USGS, 4/29/03
% - add polar plot
% Notes to Marinna and Peter Howd:
%  There are a couple of weird things:
%  1) imagedata(:,449) = 252 all the time. I just blank it out...is that
%  one point too far out the range? 
%  2) the real head angle goes retrograde sometimes. This is either a weird reading
%  in the file, or maybe an integer math thing with the angle calcs. I
%  make fake angles.

% Revised 3/8/04 by Chris Sherwood


% fan beam specific things
%settings.DegPerStep = 0.3;
settings.DegPerStep = 0.15;

pingsperrec = ((settings.SectorSweep./(settings.StepSize.*settings.DegPerStep))+1)*2;

[nangles, npoints] = size(imagedata);
slantrange = settings.SonarRange/npoints:(settings.SonarRange/npoints):settings.SonarRange;
horizrange = real((slantrange.^2 - settings.Height^2).^(1/2));

if exist('plottype') ~= 1,
  plottype = 'polar'; % default
end

switch plottype
 case 'square'
  % plot linear 
  set(gcf,'name','Square')
  set(gcf,'numbertitle','off')
  clims = [0 190];
  imagesc(headangle,horizrange,imagedata',clims)
  colormap(bone);
  colorbar
  ylabel('Horizontal Range, meters')
  xlabel('Head Position, degrees')
  text(0.01,0.05,[fname,' Fan beam image taken ',...
		  datestr(datenum(gdate))],...
       'units','normalized','color','w')
 case 'polar'
  fillval = 4; % sets value of no-data region
  rot = settings.rot
  max_range = 5;
  dxy = 0.01;    % Key setting...determines image resolution at cost of
		 % speed (reasonable range 0.02 to 0.005)
		 %figure(1)
		 %clf
  Xplot = (- max_range:dxy:max_range);
  Yplot = Xplot;
  [Xi, Yi] = meshgrid(Xplot,Yplot);
  [thi, ri]=cart2pol(Xi,Yi);
  thi = thi*180/pi;
  thi = thi+rot;
  thi(thi>180)=thi(thi>180)-360;
  thi(thi< -180)=thi(thi< -180)+360;
  fakeheadangle = linspace(headangle(1), headangle(nangles), ...
			   nangles)';
  fakeheadangle = -fakeheadangle; % because sonar scans from -160 to +170
  % pad ranges
  slantrange = [0,slantrange(1,1)-.1,...
		 slantrange(1,:), slantrange(1,npoints)+.1, 9];
  % pad angles to get complete circle
  lopad = [180; fakeheadangle(1)+.01];
  hipad = [fakeheadangle(nangles)-.01; -179.999];
  nlo = length(lopad);
  nhi = length(hipad);
  fakeheadangle = [lopad(:); fakeheadangle; hipad(:)];
  % pad data
  Zpad = (fillval)*ones(nangles+nlo+nhi,npoints+4);       
  imagedata(imagedata<(1))=(fillval);
  % kludge...last range values always seems to be 252
  imagedata(:,449)=(fillval);
  Zpad(nlo+1:nangles+nlo,3:npoints+2)=imagedata;
  Zpad = log10(Zpad);
  % interpolate
  [ripad,thpad] = meshgrid(slantrange,fakeheadangle);
  Zi = interp2( ripad,thpad,Zpad, ri, thi);
  %    Zi(Zi<1)=(8); % produces weird contrasty plot
  imagesc(Xplot,Yplot,Zi)
  set(gca,'ydir','normal') % because imagesc is sidedownup
  colormap gray;
  axis equal tight
  if(1), % plot range circles
    hold on
    for icirc = 1:5,
      h = circle(icirc,0,0);
      set(h,'color',[.7 .7 .6])
    end
  end
  text(0.01,0.03,fname,...
       'units','normalized','color','y','fontsize',14)
  text(0.8,0.95,'\uparrow North',...
       'units','normalized','color','y','fontsize',14)
  text(0.57,0.03,datestr(datenum(gdate)),...
       'units','normalized','color','y','fontsize',14)
  
 case 'prange'
  % plot headposition and prange
  [ax, h1, h2] = plotyy(1:nangles,headangle,1:nangles,prange);
  title([fname,' Fan beam image taken ',datestr(datenum(gdate))])
  xlabel('Head position and profile range by ping')
  ylabel('Deg')
  %set(ax(2),'ylabel',text(0,0,'string','Prange'))
 otherwise % no plot
end