# how to get outline of multiple shapes

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Asliddin Komilov on 18 Dec 2023
Answered: Asliddin Komilov on 4 Jan 2024
Hi,
but the answer did not fit all my data, so I need help on this one too.
I have multiple shapes I need to merge into a single shape, because I have sets of shapes those I have to merge and compare with each other (put into a one plot). the set of data is attached and I can plot it like this:
plot(X(:, [1:end 1])', Y(:, [1:end 1])')
let me know, if you know how to do it, thanks.
##### 2 CommentsShow NoneHide None
Image Analyst on 18 Dec 2023
Do you require them to be shape objects or can the answer be a digital image?
Asliddin Komilov on 19 Dec 2023
I need a shape, x and y axis.

Asliddin Komilov on 4 Jan 2024
This is the final version:
cutxr=X(1:size(X)/2,:);
cutyr=Y(1:size(Y)/2,:);
cutxl=X(size(cutxr):end,:);
cutyl=Y(size(cutyr):end,:);
% plot(cutxl(:, [1:end 1])', cutyl(:, [1:end 1])'); hold on
% plot(cutxr(:, [1:end 1])', cutyr(:, [1:end 1])')
% find convex hull, use 0 for s
Kr = boundary(double(cutxr(:)),double(cutyr(:)),0);
Kl = boundary(double(cutxl(:)),double(cutyl(:)),0);
Xhr = cutxr(Kr);
Yhr = cutyr(Kr);
Xhl = cutxl(Kl);
Yhl = cutyl(Kl);
% figure
% plot(Xhr,Yhr); hold on
% plot(Xhl,Yhl)
% create shapes to get the whole figure
shapeL=polyshape(Xhl,Yhl, 'simplify', false);
shapeR=polyshape(Xhr,Yhr, 'simplify', false);
shapeRL=[shapeL shapeR];
shape=union(shapeRL);
[xxx, yyy]=boundary(shape);
% figure
% plot(xxx,yyy);
%reshape into same index length to avoid output error
XY=linspace(1, length(xxx),1000);
hullX=interp1(1:1:length(xxx),xxx,XY,'linear');
hullY=interp1(1:1:length(xxx),yyy,XY,'linear');

### More Answers (1)

Sulaymon Eshkabilov on 19 Dec 2023
Maybe you want to get something like this shape, e.g.:
for ii=1:height(X)
PGON = polyshape(X(ii,:),Y(ii,:),'Simplify',true);
plot(PGON)
hold on
end
Warning: Boundaries with fewer than 3 points were removed.
Warning: Boundaries with fewer than 3 points were removed.
Warning: Boundaries with fewer than 3 points were removed.
Warning: Boundaries with fewer than 3 points were removed.
Warning: Boundaries with fewer than 3 points were removed.
xlim([-3 3])
ylim([0, 0.2])
##### 2 CommentsShow NoneHide None
Asliddin Komilov on 19 Dec 2023
I need one shape that is from outline of all shapes and for my set of data it will look like a big letter "V".
Asliddin Komilov on 22 Dec 2023
I think it will work if the 2 halves of the data are treated separately as follows, but I don't know how to join them together and get read of common point.
cutxr=X(1:size(X)/2,:);
cutyr=Y(1:size(Y)/2,:);
cutxl=X(size(X)/2:end,:);
cutyl=Y(size(Y)/2:end,:);
% plot(cutxl(:, [1:end 1])', cutyl(:, [1:end 1])'); hold on
% plot(cutxr(:, [1:end 1])', cutyr(:, [1:end 1])')
% find convex hull
Kr = boundary(double(cutxr(:)),double(cutyr(:)),1);
Kl = boundary(double(cutxl(:)),double(cutyl(:)),1);
Xhr = cutxr(Kr);
Yhr = cutyr(Kr);
Xhl = cutxl(Kl);
Yhl = cutyl(Kl);
% plot the convex hull, show the curve endpoint
plot(Xhr,Yhr); hold on
plot(Xhl,Yhl)

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