title: Homographic image transformation distortion issue
body: <p>I am trying to transform an image using a 3D transformation matrix and assuming my camera is orthonormal.</p>
  
  <p>I am defining my homography using the plane-induced homography formula H=R-t*n'/d (with d=Inf so H=R) as given in Hartley and Zisserman Chapter 13. </p>
  
  <p>What I am confused about is when I use a rather modest rotation, the image seems to be distorting much more than I expect (I'm sure I'm not confounding radians and degrees). </p>
  
  <p>What could be going wrong here?</p>
  
  <p>I've attached my code and example output.</p>
  
  <p><img src="https://i.stack.imgur.com/pJYfy.png" alt="Example Output"></p>
  
  <pre><code>n = [0;0;-1];
  d = Inf;
  
  im = imread('cameraman.tif');
  
   rotations = [0 0.01 0.1 1 10];
  
   for ind = 1:length(rotations)
         theta = rotations(ind)*pi/180;
  
         R = [ 1     0           0 ;
             0  cos(theta) -sin(theta);
             0  sin(theta)  cos(theta)];
  
         t = [0;0;0];
  
         H = R-t*n'/d;
  
        tform = maketform('projective',H');
        imT = imtransform(im,tform);
  
        subplot(1,5,ind) ;
        imshow(imT)
        title(['Rot=' num2str(rotations(ind)) 'deg']);
        axis square
   end
  </code></pre>