interpolation of coordinates in space using interp3

조회 수: 13 (최근 30일)
Alberto Acri
Alberto Acri . 2023년 10월 1일
답변: Torsten . 2023년 10월 1일
Hi! I have this coordinate set (C_new). I would like to add additional coordinates using interpolation.
load C_new
hold on
hold off
axis equal
I'm proceeding as follows but I don't know if it's the right procedure:
X = C_new(:,1);
Y = C_new(:,2);
Z = C_new(:,3);
[Xq,Yq,Zq] = meshgrid(X,Y,Z);
Vq = interp3(X,Y,Z,V,Xq,Yq,Zq);
but what should I put for V?
  댓글 수: 1
Dyuman Joshi
Dyuman Joshi 2023년 10월 1일
You need the equation/relation between the coordinates to interpolate, V contains the values of the the function corresponding to (X,Y,Z).

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채택된 답변

Voss 2023년 10월 1일
편집: Voss 님. 2023년 10월 1일
interp3 is for interpolating a function of 3 variables, i.e., if you had a function f(X,Y,Z) that returns a value for each (X,Y,Z) then you could use interp3 to interpolate those values to new points in 3D space. In this case there is no function, only the points in 3D space, so you can define a parameterizing variable and use interp1 to interpolate each of your X, Y, Z in terms of that
load C_new
% original number of points:
n = size(C_new,1);
% number of points you want (change this as desired):
n_new = floor(n/2);
% distance between adjacent points:
d = sqrt(sum(diff(C_new,1,1).^2,2));
% cumulative distance around the ring, starting with point #1:
t = [0; cumsum(d)];
% new distances (equally-spaced) at which to calculate the new (X,Y,Z) coordinates:
t_new = linspace(t(1),t(end),n_new);
% interp1 C_new from t to t_new:
C_interp = interp1(t,C_new,t_new);
% plot:
hold on
axis equal

추가 답변 (1개)

Torsten 2023년 10월 1일
Given two points
P1 = [1 3 4];
P2 = [3 6 -1];
you can connect them by a line
s = @(t) (1-t)*P1 + t*P2;
and choose points between them:
t = [0:0.2:1];
Pq = reshape(cell2mat(arrayfun(@(t)s(t),t,'UniformOutput',0)),3,[]).'
Pq = 6×3
1.0000 3.0000 4.0000 1.4000 3.6000 3.0000 1.8000 4.2000 2.0000 2.2000 4.8000 1.0000 2.6000 5.4000 -0.0000 3.0000 6.0000 -1.0000


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