isneighbour.m

it is a matlab file foe develop SLAM localization this is a toolbox for develop develop realtime e

%ISNEIGHBOUR Check if line segments are adjacent.
%   ISNEIGHBOUR(RAWSEGS,I,J,OVERLAP,CYC) returns 1 if segments I
%   and J are adjacent (with OVERLAP = 0) or if segments I and J
%   are adjacent *and* overlap (with OVERLAP = 1). Takes into
%   account cyclic (CYC = 1) and noncyclic (CYC = 0) scans. Uses
%   the RAWSEGS matrix defined in EXTRACTLINES.
%
%   See also EXTRACTLINES.

% v.1.0, 17.01.99, Kai Arras, ASL-EPFL
% v.1.1, 07.12.02, Kai Arras, ASL-EPFL: overlap added
% v.1.2, 30.09.03, Kai Arras, CAS-KTH: Bug fix in overlap condition

function bool = isneighbour(rawsegs,si,sj,overlap,cyc);

nRawSegs  = size(rawsegs,2);
neighbour = 0;

% Determine neighbourship
terminate = 0; i = 1;
while (i <= nRawSegs) & ~terminate,
  if (i < nRawSegs) | cyc,
    j = mod2(i + 1, nRawSegs);
    if ((rawsegs(1,i)==si)&(rawsegs(1,j)==sj)) | ((rawsegs(1,i)==sj)&(rawsegs(1,j)==si)),
      terminate = 1; neighbour = 1;
    end;
  end;
  i = i + 1;
end;

% Determine overlap
if neighbour & overlap,
  i = i - 1;   % compensate last i increment
  is1 = rawsegs(2,i);
  ie1 = rawsegs(3,i);
  is2 = rawsegs(2,j);
  ie2 = rawsegs(3,j);
  c11 = (ie1 >= is1);
  c22 = (ie2 >= is2);
  c12 = (ie1 >= is2);
  c21 = (ie2 >= is1);
  if (c11 & c22 &  c12 &  c21) | (~c11 &  c22 & c12 & ~c21) | ...
     (c11 & c22 & ~c12 & ~c21) | ( c11 & ~c22 & c12 & ~c21),
    bool = 1;
  else
    bool = 0;
  end;
else
  bool = neighbour;
end;