function [h,hx,hy]=fill_potholes(h,hx,hy)
%
% Fills "pot holes": holes deeper than all neighbouring sides
%
% e.g.
%      [H2,Hx2,Hy2]=fill_potholes(H2,Hx2,Hy2);

if size(h)~=size(hx) | size(h)~=size(hy)
 error('Arguments must all be the same size!\n');
end

% Fill-up cell-centers where all sides are higher
Hsides=min( hx, hx([2:end 1],:,:) );
Hsides=min( Hsides, hy );
Hsides=min( Hsides, hy(:,[2:end end],:) );
h=max( h, Hsides );