MATLAB Answers

Draw arc with specified angle difference

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Elysi Cochin
Elysi Cochin 2021 年 6 月 9 日
コメント済み: Star Strider 2021 年 6 月 10 日
Having 2 datas as attached in Data.mat, how to draw arc with a specified angle difference (angle difference can vary say 15, 30 or any other value as given by user)
The data columns in order are angle, radius, depth
How can i find the center with the attached data, so that both the arcs pass through the center, and display it in x,y,z coordinate
  3 件のコメント
Elysi Cochin
Elysi Cochin 2021 年 6 月 9 日
Sir, can you show me how to plot, if the angles are radian values (descending spiral)



Star Strider
Star Strider 2021 年 6 月 9 日
Try this —
LD = load('Data.mat');
Data1 = LD.Data1;
A1 = Data1(:,1);
R1 = Data1(:,2);
D1 = Data1(:,3);
Data2 = LD.Data2;
A2 = Data2(:,1);
R2 = Data2(:,2);
D2 = Data2(:,3);
ctrfcn = @(b,a,r,d) [sqrt((b(1)+r.*cosd(a)).^2 + (b(2)+r.*sind(a)).^2 + (b(3)-d).^2)];
[B1,fval] = fminsearch(@(b)norm(ctrfcn(b,A1,R1,D1)), -rand(3,1)*1E+4)
[B2,fval] = fminsearch(@(b)norm(ctrfcn(b,A2,R2,D2)), -rand(3,1)*1E+4)
plot3(R1.*cosd(A1), R1.*sind(A1), D1, 'm')
hold on
plot3(R2.*cosd(A2), R2.*sind(A2), D2, 'c')
scatter3(B1(1), B1(2), B1(3), 30, 'm', 'p', 'filled')
scatter3(B2(1), B2(2), B2(3), 30, 'c', 'p', 'filled')
hold off
legend('Data_1','Data_2', 'Centre_1', 'Centre_2', 'Location','best')
grid on
The axes are not scaled to be equal, because it then appears to be a flat surface.
Data1 Center:
x = -740.85
y = -349.01
z = 3.83
Data2 Center:
x = -740.96
y = -348.77
z = 3.81
  5 件のコメント
Star Strider
Star Strider 2021 年 6 月 10 日
As a general rule when talking about arcs or circles, the center is the center of the circle. It can never be on any of the circumferences.
You are asking for the midpoint of the arc.
MP1 = median([R1.*cosd(A1)+B1(1), R1.*sind(A1)+B1(2), D1],1);
MP2 = median([R2.*cosd(A2)+B2(1), R2.*sind(A2)+B2(2), D2],1);
fprintf(1,'Arc Midpoint 1:\n\t\tx = %8.2f\n\t\ty = %8.2f\n\t\tz = %8.2f\n',MP1)
fprintf(1,'Arc Midpoint 2:\n\t\tx = %8.2f\n\t\ty = %8.2f\n\t\tz = %8.2f\n',MP2)
produces —
Arc Midpoint 1:
x = 745.33
y = 366.43
z = 3.83
Arc Midpoint 2:
x = 752.68
y = 364.83
z = 3.82
That is the best I can do.


その他の回答 (2 件)

Image Analyst
Image Analyst 2021 年 6 月 9 日
  1 件のコメント
Elysi Cochin
Elysi Cochin 2021 年 6 月 9 日
Sir, i saw that link, but the data I have, is different with the example shown in the link.


darova 2021 年 6 月 9 日
Wha about this representation?
s = load('data.mat');
t = linspace(0,1,20)*pi/180; % angle array
[X,Y,Z] = deal( zeros(10,20) ); % preallocation matrices
for i = 1:10
[X(i,:),Y(i,:)] = pol2cart(t*s.Data1(i,1),s.Data1(i,2)); % create arc
Z(i,:) = s.Data1(i,3); % depth
  1 件のコメント
Elysi Cochin
Elysi Cochin 2021 年 6 月 9 日
Sir how to convert the radius value from degrees to radians and plot the figure
also, at a time i want to give only one angle



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