FASTCORNER - Wrapper of functions for fast corner detection.

Contents

Description

Nothing else than a wrapper for the functions [FAST] of the FAST method of [RD05,RD06] used for corner detection.

Syntax

  ptcorner = FASTCORNER(I);
  [ptcorner, cornermap] = FASTCORNER(I, 'Property', propertyvalue,... );

Inputs

I : image.

numa : (optional) string or scalar value setting the fast method to be used; it is any number/char in {9,10,11,12}; default: numa='9'.

nonmax : (optional) logical flag for operating non maximum suppression; default: nonmax=true.

thres : thres to apply; default: thres=1.

Outputs

ptcorner : list of corner points.

cornermap : 2D spatial representation of ptcorner; cornermap is a logical matrix.

References

[RD05] E. Rosten and T. Drummond: "Fusing points and lines for high performance tracking", Proc. ICCV, vol. 2, pp 1508-1511, 2005. http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1544896

[RD06] E. Rosten and T. Drummond: "Machine learning for high-speed corner detection", Proc. ECCV, vol. 1, pp 430-443, 2006.

[FAST] Source code available at http://mi.eng.cam.ac.uk/~er258/work/fast.html and http://www.mathworks.com/matlabcentral/fileexchange/13006-fast-corner-detector.

See also

Ressembles: CORNER, EDGECORNER, SUSANCORNER, HARRISCORNER, FASTCPDA, COMPASSEDGE, CONGRUENCYEDGE. Requires: FASTCORNER_BASE.

Function implementation

function [ptcorner,cornermap] = fastcorner(I,varargin)

% %% Check if possible
% if ~exist('fast_mex','file')
%     error('mex file fast_mex not found');
% end

parsing parameters

error(nargchk(1, 12, nargin, 'struct'));
error(nargoutchk(1, 2, nargout, 'struct'));

% mandatory parameter
if ~isnumeric(I)
    error('fastcorner:inputerror','matrix required in input');
end

% optional parameters
p = createParser('FASTCORNER');
% principal optional parameters
p.addOptional('numa', 9, @(x) (isscalar(x) && ismember(x,[9,10,11,12])) || ...
    (ischar(x) && any(strcmpi(x,{'9','10','11','12'}))));
p.addOptional('nonmax', true, @(x)islogical(x));
% additional optional parameters
p.addOptional('thres', 1, @(x)isscalar(x) && x>=0);

% parse and validate all input arguments
p.parse(varargin{:});
p = getvarParser(p);

setting internal variables

if ischar(p.numa), p.numa = str2double(p.numa);  end;

main processing

[ptcorner, cornermap] = fastcorner_base(I, p.numa, p.nonmax, p.thres);

display

if p.disp
    figure, imagesc(cornermap), axis image off;
    if size(cornermap,3)==1, colormap gray;  end;
    title('corners detected with FAST');
end

end % end of fastcorner