Dividing the point cloud in 10x10 ways

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Ahmet Selim Arslan 2021-3-23

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https://ww2.mathworks.cn/matlabcentral/answers/781248-dividing-the-point-cloud-in-10x10-ways

评论： Ahmet Selim Arslan 2021-4-11

Hello, my problem is that I am working on a 3-dimensional point cloud like in the title and I want to split it into 10x10 pieces over x and y. As I am new to Matlab, I didn't know how to do this for now.

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回答（2 个）

Adam Danz 2021-3-29

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https://ww2.mathworks.cn/matlabcentral/answers/781248-dividing-the-point-cloud-in-10x10-ways#answer_661594

编辑：Adam Danz 2021-4-1

在 MATLAB Online 中打开

Load built-in pointcloud data and look at the pointcloud object pc

load('xyzPoints');

pc = pointCloud(xyzPoints)

pc =

pointCloud with properties: Location: [5184×3 single] Count: 5184 XLimits: [-3 3.4338] YLimits: [-2 2] ZLimits: [0.0016 3.1437] Color: [] Normal: [] Intensity: []

X/Y/ZLimits are the range of x,y,z points. Create a 10x10 grid within the x and y ranges. The bounds are defined in xyBounds (nx2).

[x,y] = meshgrid(linspace(pc.XLimits(1), pc.XLimits(2), 10), ...
    linspace(pc.YLimits(1), pc.YLimits(2), 10));
xyBounds = [x(:),y(:)]
xyBounds = 100×2
   -3.0000   -2.0000
   -3.0000   -1.5556
   -3.0000   -1.1111
   -3.0000   -0.6667
   -3.0000   -0.2222
   -3.0000    0.2222
   -3.0000    0.6667
   -3.0000    1.1111
   -3.0000    1.5556
   -3.0000    2.0000

Use indexing to access a particular section of points.

Get all points within the bin #n

pc.Location are all [x,y,z] coordinates.
idx is a logical vector identifying points in pc.Location that are in the bin
section are the [x,y,z] coordinates within the bin.

n = 50;  % 50th bin xyBounds(n,:) 
xIdx = pc.Location(:,1) >= xyBounds(n,1) & pc.Location(:,1) < xyBounds(n+1,1);
yIdx = pc.Location(:,2) >= xyBounds(n+1,2) & pc.Location(:,2) < xyBounds(n,2);
idx = xIdx & yIdx;
section = pc.Location(idx,:)
section = 1150×3
         0   -1.5000    2.4000
         0   -1.4537    2.4694
         0   -1.4099    2.4977
         0   -1.3830    2.4849
         0   -1.3874    2.4309
    0.0705   -1.4758    2.4399
    0.0682   -1.4290    2.4887
    0.0665   -1.3919    2.4964
    0.0658   -1.3789    2.4630
    0.1421   -1.4936    2.4000

Some bins will not have any points and will return a 0x3 empty matrix.

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Ahmet Selim Arslan 2021-4-10

When I say show with plot, it shows such a result.

Ahmet Selim Arslan 2021-4-11

Okay, let's take it over again, I apologize for not being able to explain it in a nice and understandable language.As you can see, I want to divide the point cloud into 100 equal parts and distribute the height randomly and see this in the graph. I'm sorry if I haven't been revealing before

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darova 2021-3-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/781248-dividing-the-point-cloud-in-10x10-ways#answer_656998

在 MATLAB Online 中打开

see this example

clc,clear
x = rand(10,10,10);
y = rand(10,10,10);
z = rand(10,10,10);
ix = round(5*x);
iy = round(5*y);
plot3(x(:),y(:),z(:),'.b');
hold on
h = plot3(0,0,0,'or');
hold off
view(15,60)
for i = 1:5
    for j = 1:5
        ind = (i==ix) & (j==iy);
        set(h,'xdata',x(ind))
        set(h,'ydata',y(ind))
        set(h,'zdata',z(ind))
        pause(0.2)
    end
end