How to plot a curve tangent to many ellipses.

2 次查看（过去 30 天）

Majid 2021-3-8

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/766041-how-to-plot-a-curve-tangent-to-many-ellipses

评论： Majid 2021-9-23

Hi everybody,

In the attached figures, we have two kind of curve; 1- a big closed curve which is somehow a limaçon. 2- many ellipses which are the same by the formula but different by the center. In fact, we have the same rotated ellipses

whose centers vary on the points on the limaçon. I added two figures in which the number of added ellipses are different (just to make more confortable to understand the question). Now, I want to add a new curve in the figure which is tangent to all the ellipses. For now, I have no idea how to do it.

Any help is appreciated in advance.

I should say that I can add as many as ellipses I want.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Matt J 2021-3-10

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/766041-how-to-plot-a-curve-tangent-to-many-ellipses#answer_644412

在 MATLAB Online 中打开

You could also try,

P =[X Y]; 
P = unique(P,'row'); 
k=convhull(P);
Xh=P(k,1); Yh=P(k,2);
line(Xh,Yh)

4 个评论
显示 2更早的评论隐藏 2更早的评论

Matt J 2021-9-21

You can probably take the convhull() as before to get the envelope points and use an alphaShape() as in this example to plot a surface:

https://www.mathworks.com/help/matlab/ref/alphashape.html#buh3a23-1

Majid 2021-9-23

I highly appreciate your suggestion. It worked very well.

请先登录，再进行评论。

更多回答（2 个）

Matt J 2021-3-8

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/766041-how-to-plot-a-curve-tangent-to-many-ellipses#answer_642321

alphaShape.boundaryFacets might also be applicable,

https://www.mathworks.com/help/matlab/ref/alphashape.boundaryfacets.html

7 个评论
显示 5更早的评论隐藏 5更早的评论

Majid 2021-3-10

编辑：Majid 2021-3-10

Then, if this is the case, I am not getting your point! I am not so familiar with MATLAB functions in particular I know this function since I have seen your comment here. So, could you please let me know how can I get to the outer curve in more details?

PS: As I am not so familiar with MATLAB, I am trying to find out the coordinates of the points on the outer curve mathematically to be able to plot it in MATLAB. I think I will get there in a day.

Matt J 2021-3-11

As you may see in the enclosed figures below, I first gathered the coordinates of all the points on all the ellipses in the vectors X and Y, and then tried

It would be advisable to attach your X,Y vectors in a .mat file so that we can demonstrate more directly.

请先登录，再进行评论。

darova 2021-3-8

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/766041-how-to-plot-a-curve-tangent-to-many-ellipses#answer_642241

Did you try boundary?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Majid 2021-3-9

Thanks! It seems that the link provided by Matt J is about the concept you mentioned. I did not know about these functions, and so I had not tried it. But, I am on it.

请先登录，再进行评论。

请先登录，再回答此问题。