Create mesh from matrix

2023 10 11
2 个回答
回答已采纳
更新时间：2023 10 13
4 次查看（30 天）

0 个投票

I have two matrix a and b, which have dimension of 241 x 360. The values from the a and b gives a mesh. How do I plot the mesh?

8 个评论
显示 6更早的评论 隐藏 6更早的评论

Walter Roberson
Walter Roberson 2023-10-11
Could you give an example of what you are hoping the output might look like?
Kiran
Kiran 2023-10-11
For example, lets assume a and b are 2x2 matrix. where the elemnts values are,
a(1,1) = 0, a(1,2) = 2 , a(2,1) = 0, a(2,2) = 2
b(1,1) = 0, b(1,2) = 23 , b(2,1) = 50, b(2,2) = 50
This represents the four corner of a quadrilateral, with respective combination of indices. Like, a(1,1) and b(1,1) first corner and so on.
the cyclist
the cyclist 2023-10-12
编辑：the cyclist 2023-10-12
OK, so for your small example, what would the output actually be? Don't worry how to calculate it. Just tell us the output result.
a = [0 2;
0 2];
b = [ 0 23;
50 50];
ab_mesh = ????
Walter Roberson
Walter Roberson 2023-10-12
Are you trying to create a solid? Where the bottom is given by one of the matrices and the top is given by the other matrix, and they are assumed to be some set distance apart? If so then how do you want to handle the situation where they have different number of vertices?
Kiran
Kiran 2023-10-12
The output on matlab should look like this. A grid formed using martix a and b.
Walter Roberson
Walter Roberson 2023-10-12
@Kiran
But you asked for a mesh, and what you show is not a mesh.
Kiran
Kiran 2023-10-12
Yes, but that's just for example the real matrix has dimension 241 x 55298 for a and b, so lot of points to form grid. My question was, can we get a grid in matlab if we know the elements of a and b?
Image Analyst
Image Analyst 2023-10-12
@Kiran did you even see my answer from yesterday below (scroll down)?

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Walter Roberson
Walter Roberson 2023-10-12
Ran in:

0 个投票

Ran in:
a = [0 2 3;
0 2 4];
b = [ 0 2.3 4;
5 5 3];
h = size(a,1);
w = size(a,2);
idx = reshape(sub2ind([h, w], 1:h*w), h, w);
tl = idx(1:end-1, 1:end-1);
tr = idx(1:end-1, 2:end);
ll = idx(2:end, 1:end-1);
lr = idx(2:end, 2:end);
T = [tl(:), ll(:), lr(:), tr(:)];
X = [a(:), b(:), zeros(numel(a),1)];
tetramesh(T, X)
view(2)

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Walter Roberson
Walter Roberson 2023-10-13
Ran in:
Ran in:
The sub2ind() is not needed...
a = [0 2 3;
0 2 4];
b = [ 0 2.3 4;
5 5 3];
h = size(a,1);
w = size(a,2);
idx = reshape(1:h*w, h, w);
tl = idx(1:end-1, 1:end-1);
tr = idx(1:end-1, 2:end);
ll = idx(2:end, 1:end-1);
lr = idx(2:end, 2:end);
T = [tl(:), ll(:), lr(:), tr(:)];
X = [a(:), b(:), zeros(numel(a),1)];
tetramesh(T, X)
view(2)

请先登录，再进行评论。

更多回答（1 个）

Image Analyst
Image Analyst 2023-10-12

0 个投票

Not sure what you mean by "plot" but to view a and b as 2-D images and 2.5-D surface plots:
subplot(2, 2, 1);
imshow(a, []);
subplot(2, 2, 2);
imshow(b, []);
subplot(2, 2, 3);
surf(a);
subplot(2, 2, 4);
surf(b);
Or you could simply double click on a and b in the workspace panel to bring them up in the variable editor panel in MATLAB.

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Kiran
Kiran 2023-10-12
I got something like this. But, can you let me know hwo to get a 2d plot, like in the sketch?

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 2-D and 3-D Plots 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by