How can i estiamte the local distance between two boundaries at each point ??

I attched image and .mat file of boundaries. We want to measure the distnace between red and green boundary at each point which is shown in image_1. We are calulated distrance using pdist2() function, but it gives distance from first point on boundary_1 to all points of boundary_2 and so on. But It should calculate the distance between one points on boundary_1 (red colour boundary in image_1) and nearest point on another boundary(green colour boundary in image_1).

[Surendra Ratnu]

Thank you for your answer chunru. How can i draw the lines between boundary one and boundary 2 so i can identify which points are taken for min distance.

Answer 1

[Chunru]

load(websave("bw1.mat", "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1153258/bw1.mat"))
load(websave("bw2.mat", "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1153263/bw2.mat"))

d = pdist2(M, N);

plot(M(:,1), M(:, 2), 'r-', N(:,1), N(:,2), 'g');
set(gca, 'YDir', 'reverse');
axis equal
hold on
for i=1:10:size(d, 1)  % change 10 to 1 for every points
    [~, imin] = min(d(i, :));   % closest distant to boundary 2

    plot([M(i,1) N(imin,1)], [M(i,2) N(imin,2)], 'b-')
end

% whos

[Surendra Ratnu]

Thank you for your answer. How can i draw the lines between boundary one and boundary 2 so i can identify which points are taken for min distance.

[Chunru]

See the updated.

[Image Analyst]

Might be fun/interesting to show a histogram of distances, and area of the annular region using polyarea.

[Surendra Ratnu]

I got your point churnu. In image_m (which i attched), with help of this code, I can not measure the distance d which is shown in image_m. Can you provide your some solution so i can calculate the distance d for all extruded part (which is the extruded part of green boundary in image_m).

[Chunru]

In that case, you need to swap the reg and green lines.

load(websave("bw1.mat", "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1153258/bw1.mat"))
load(websave("bw2.mat", "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1153263/bw2.mat"))
d = pdist2(M, N);
plot(M(:,1), M(:, 2), 'r-', N(:,1), N(:,2), 'g');
set(gca, 'YDir', 'reverse');
axis equal
hold on
for i=1:10:size(d, 2)  % change 10 to 1 for every points
    [~, imin] = min(d(:, i));   % closest distant to boundary 2
    plot([M(imin,1) N(i,1)], [M(imin,2) N(i,2)], 'b-')
end
axis([200 400 400 500])  % zoom in

[Surendra Ratnu]

I agreed with your point churnu, but there are number of lines. You can see in image(attached in this comment), i need only distance d which is shown in image. This distance can not reconize. Can you give some suggestion on that and how to calculate the angle alpha which is shown in angle.png imag.

[Chunru]

Then you have to specify which point to be examined. And then just show the distance for the specified point.

[Surendra Ratnu]

But in my case there are no of extruded parts and i want to automated them to calculate the length of the extruded part. Can you eloborate on this.