How can I assign a unique label to all points lying inside a single sub-region of divided 3D space?

1 view (last 30 days)
Suppose I have a 3D space. I have divided it using grids with X = 0:2:6, Y = 0:1:6 and Z = 0:3:9. So that now I have 54 small 3D regions. Few points are scattered in the entire 3D region. I have to find how many points are lying inside individual small region. Also I have to assign a label for all points in each region, e.g. All points in region 1 will have label 1, all in region 2 will be label 2, so on. I have added the picture for the reference.
Is there any direct function in matlab to find a solution for this problem ? Using if else conditions would be complex if the number of grids and dimensions increases. Is there any idea or hint ?

Answers (2)

KSSV on 25 Jun 2018
Go for logical indexing......If (X,y,z) are you points. To get the points lying between (x1,y1,z1) and (x2,y2,z2) ;
idx = (x>x1 & x<=x2) & (y>y1 & y<=y2) & (z>z1 & z<=z2) ;
Initilize your label matrix and fill the value you want for the above idx.

Walter Roberson
Walter Roberson on 25 Jun 2018
Let the coordinates of the points be stored in x, y, z
nx = 3; ny = 6; nz = 3;
xb = floor(x/2)+1;
yb = floor(y)+1;
zb = floor(z/3)+1;
counts = accumarray([xb(:), yb(:), zb(:)], 1, [nx, ny, nz]);
labels = sub2ind([nx, ny, nz], xb, yb, zb);


Find more on 3-D Scene Control in Help Center and File Exchange

Community Treasure Hunt

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

Start Hunting!