Establishment of vectors in 2D coordinate system based on 2D image

Dear all, I wish I could construct the coordinate system based on 2D image in Matlab.

I have a image as attached:

I wish I could find the vector of long axis for each object, like attached:

My thought is to use the different pixel information to specify the objects, but I'm not sure how to implement it.

I established coordinate system via following command

clear
clc
close all
A=imread('2D_try.jpg')
A=gpuArray(A)
B=imshow(A)
C=impixelinfo(B)

Could you give me a comment or suggestion?

Wish all of you have a nice weekend!

Sincerely

Answer 1

[Matt J]

load image
T=bwferet(B);
C=cell2mat(T.MaxCoordinates);
X1=C(1:2:end,1); Y1=C(1:2:end,2);
X2=C(2:2:end,1); Y2=C(2:2:end,2);

imshow(B);
hold on;
quiver(X1,Y1,X2-X1,Y2-Y1,'-y','AutoScale','off','LineWidth',3);
hold off

[Daniel Chou]

Dear Matt,

I really appreciate for your demonstration !!!

This is what I need.

Wish you have a good day :)

Sincerely

Daniel Chou