Comparing two images' point location & movement of an position of a point in video

I have two images that are taken in similar angle but different distance.

What i want to do is, when I click one image, I want to get mark of same location of the other image.

There're 4 markers and I already get marker point.

Is there any way I could compare the same position of two images?

Also, I have a video file and it has 4 markers. This video moves so makers move too.

What i want to do is, when I mark one position(which is not position of 4 markers), I want to calculate how it moves by using 4 markers.

Is there any way I could calculate the movement of an mark by using 4 markers?

Thanks!!!

Answer 1

[Udit06]

Hi Jaeyoung,

For the first question, you can use SIFT (Scale Invariant Feature Transform) to extract features from the images. Using the extracted features, you can then compare both the images having different scale. To extract SIFT features in MATLAB, you can use “detectSIFTFeatures” function: https://www.mathworks.com/help/vision/ref/detectsiftfeatures.html?s_tid=doc_ta

For the second question, you can follow the process mentioned below:

1. Detect four marker points using a feature detection algorithm like SURF. You can use “detectSURFFeatures” MATLAB function to extract the SURF features. Refer to: https://www.mathworks.com/help/vision/ref/detectsurffeatures.html?s_tid=doc_ta
2. Establish a coordinate system by defining the positions of four reference markers using “fitgeotform2d” MATLAB function. Refer to: https://www.mathworks.com/help/images/ref/fitgeotform2d.html
3. Estimate the geometric transformation between the new frames and the referenced frame. You can use “estgeotform2d” MATLAB function for the same. Refer to: https://www.mathworks.com/help/vision/ref/estgeotform2d.html
4. Once you have the estimated transformation, you can apply it to the position of the desired point in each frame to obtain its position in the reference frame.

I hope this helps.