Code covered by the BSD License

# OpenSURF (including Image Warp)

### Dirk-Jan Kroon (view profile)

26 Jul 2010 (Updated )

SURF (Speeded Up Robust Features) image feature point detection / matching, as in SIFT

example2.m
```% Example 2, Corresponding points
% Get the Key Points
Options.upright=true;
Options.tresh=0.0001;
Ipts1=OpenSurf(I1,Options);
Ipts2=OpenSurf(I2,Options);
% Put the landmark descriptors in a matrix
D1 = reshape([Ipts1.descriptor],64,[]);
D2 = reshape([Ipts2.descriptor],64,[]);
% Find the best matches
err=zeros(1,length(Ipts1));
cor1=1:length(Ipts1);
cor2=zeros(1,length(Ipts1));
for i=1:length(Ipts1),
distance=sum((D2-repmat(D1(:,i),[1 length(Ipts2)])).^2,1);
[err(i),cor2(i)]=min(distance);
end
% Sort matches on vector distance
[err, ind]=sort(err);
cor1=cor1(ind);
cor2=cor2(ind);
% Show both images
I = zeros([size(I1,1) size(I1,2)*2 size(I1,3)]);
I(:,1:size(I1,2),:)=I1; I(:,size(I1,2)+1:size(I1,2)+size(I2,2),:)=I2;
figure, imshow(I/255); hold on;
% Show the best matches
for i=1:30,
c=rand(1,3);
plot([Ipts1(cor1(i)).x Ipts2(cor2(i)).x+size(I1,2)],[Ipts1(cor1(i)).y Ipts2(cor2(i)).y],'-','Color',c)
plot([Ipts1(cor1(i)).x Ipts2(cor2(i)).x+size(I1,2)],[Ipts1(cor1(i)).y Ipts2(cor2(i)).y],'o','Color',c)
end```