How to make an X by 3 matrix into a grid of points

2 次查看（过去 30 天）
Joph
Joph 2014-6-22
回答： DGM 2025-7-13
So currently I have a 262014x3 matrix that has 262014 coordinates of an image.
To be able to use this for my application it has to be a 3D matrix of binary points. So I want to put a point in a, let's say, 512x512x512 matrix (I know, I'll lose a lot of definition, that's not the concern), how would I go about that?
Just a side note, the initial matrix was made by using stlread (as found here http://www.mathworks.com/matlabcentral/fileexchange/29906-binary-stl-file-reader) And I'm only using the coordinates of the vertices.

请先登录，再回答此问题。

采纳的回答

Image Analyst
Image Analyst 2014-6-22
Try this:
m3d = false(512,512,512); % Initialize binary image.
for row = 1 : size(coordinates, 1)
row = coordinates(row, 1);
col = coordinates(row, 2);
slice = coordinates(row, 3);
m3d(row, col, slice) = true;
end
  7 个评论
显示 5更早的评论
Joph
Joph 2014-6-22
Well the thing is the points from readSTL were from 93.137-98.463 for x, 121.354-127.352 for y, and 45.362-49.234 for z. So I just multiplied them by 1000 since scale isn't a problem, but the precision is still relevant and going down to 3 digits obscures the image too much.
And yeah, I guess I could get more memory, I was just trying to see if there was a less memory intensive answer available, but no worries.
Thanks for the help!
John D'Errico
John D'Errico 2014-6-22
I'm confused. Subtract the min, then multiply by 511/(max - min), add 1. This will scale it to 1-512. Then round.
If you are truly memory limited, then use a bit smaller matrix.
If you really just want to visualize the points as a scatter cloud, then why not use plot3 in one call? If your goal is really to visualize this as an object, then use an alpha shape, or a convex hull if the set is convex.

请先登录，再进行评论。

更多回答（1 个）

DGM
DGM 2025-7-13

类别

在 Help Center 和 File Exchange 中查找有关 Lighting, Transparency, and Shading 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