finding covered regions created by intersecting random lines

hey, i am trying to find covered areas by random lines as seen in the figure (i need to produce much complex structures). The intersects (or node points) are kept in a Sparse matrix. (I manually added a red dot as an example)

[John D'Errico]

Are you looking only for regions that are entirely enclosed in 2-d by some set of line segments?

[Mustafa Codur]

it is right. I have intersects and i want to have the intersect nodes numbers which are covering the region. not with image processing. For example, Region1 consists of 34th,25th,42th nodes.

although there is a paper mentions about an algorithm i could not get that;

https://www.inesc-id.pt/ficheiros/publicacoes/936.pdf

Answer 1

[darova]

Here is the method using bwlabel

clear
clc

I = zeros(100);
    % random coordinates of lines
x = rand(20,2)*98+1;        
y = rand(20,2)*98+1;
    % horizontal and vertical lenghts
dx = abs(diff(x,[],2));
dy = abs(diff(y,[],2));
for i = 1:size(x,1)
    n = max(dx(i),dy(i));           % max length
    n = round(n);
    x1 = linspace(x(i,1),x(i,2),n); 
    y1 = linspace(y(i,1),y(i,2),n);
    ind = sub2ind(size(I),round(y1),round(x1));
    I(ind) = 1;                     % burn line
end

[I1,m] = bwlabel(~I,4);             % separate each region
imshow(I1,rand(n,3))