PERIMETER OF A 3D POLYGON WHICH DOES NOT LIE IN THE X-Y PLANE
조회 수: 2 (최근 30일)
이전 댓글 표시
Hi everyone,
I have the spatial coordinates (x,y,z) of a cloud of points.
To date, I am able to calculate the area of the polygon in space obtained interpolating these points. Any suggestions abou how to calculate the perimeter?
Thank you in advance
댓글 수: 6
Bjorn Gustavsson
2022년 7월 5일
@Torsten: In 3-D it isn't obvious that a cloud of points are flat. There would still be a "natural" area from the convex hull, but I wasn't sure there would be a unique perimeter. But now I see that the points seem to lie in a plane - or near enough.
채택된 답변
Torsten
2022년 7월 5일
The code should apply to your case:
x = 3*cos(0:pi/20:2*pi);
y = 3*sin(0:pi/20:2*pi);
fn = cscvn([x;y]);
% Compute enclosed area
fnprime = fnder(fn);
Kofs = @(s) [1 -1]*(fnval(fn,s) .* flipud(fnval(fnprime,s)));
A = 1/2*integral(Kofs,fn.breaks(1),fn.breaks(end))
pi*3^2
% Compute curve length
Lfun = @(s) sqrt(sum(fnval(fnprime,s).^2,1));
L = integral(Lfun,fn.breaks(1),fn.breaks(end))
2*pi*3
댓글 수: 2
추가 답변 (0개)
참고 항목
카테고리
Help Center 및 File Exchange에서 Computational Geometry에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!