MATLAB: How to eliminate erroneous match(es) in matchFeatures example

Question

Hi all,

I have a set of images that are taken from the dash cam of a car. I am trying to find a set of corresponding points in two successive frames to estimate the direction of the car. (I will use this information to obtain the visual odometry of the car). I used the match features code given here: https://www.mathworks.com/help/vision/ref/matchfeatures.html

But sometimes I am getting wrong matches. For example:

My function:

function [matchedPoints1, matchedPoints2] = Corresponding_Points(Im1,Im2)
    %%Find Corresponding Interest Points Between Pair of Images
      % Find the corners.
      points1 = detectHarrisFeatures(Im1);
      points2 = detectHarrisFeatures(Im2);
      % Extract the neighborhood features.
      [features1,valid_points1] = extractFeatures(Im1,points1);
      [features2,valid_points2] = extractFeatures(Im2,points2);  
      % Match the features.
      indexPairs = matchFeatures(features1,features2);   
      % Retrieve the locations of the corresponding points for each image.
      matchedPoints1 = valid_points1(indexPairs(:,1),:);
      matchedPoints2 = valid_points2(indexPairs(:,2),:); 
end

My code:

    [matchedPoints1, matchedPoints2] = Corresponding_Points(image_1_gray,image_2_gray);
    x1 = matchedPoints1.Location';
    x2 = matchedPoints2.Location';

Note: the returned matchedPoints1 and matchedPoints2 belong to class cornerPoints . Using matchedPoints1.Location returns a matrix type single. (I am using Matlab 2016a.)

Thanks!

Answer 1

Do you know the (x,y) coordinates of each? You could just throw out any pairs where the distance between them is more than, say 10% of the image width.