Make grid from patch object

2018 1 25
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更新时间：2018 1 27
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Hi
I am trying to make a function for splitting a patch object into N equally sized indexed rectangles (like a grid). The intended use is that the patch object contains the (x,y) values for a floor in a room, and I want to split the room into N number of rectangles which later will be used to make a "Region of Interest" in an optimization problem.
Any help would be highly appreciated.

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Rik
Rik 2018-1-25
It might be an overpowered tool, but the FEX submission intriangulation might be of help here.
Walter Roberson
Walter Roberson 2018-1-25
So for example it needs to be able to divide up a room that looks like this:
-----
| |
________| |
| |
| ___|
| |
|________|
into
-----
| |
________| |
| + + |
| + +___|
| + |
|___+____|
for N = 3, declare failure for N = 4 or N =5, for N = 6 it could subdivide those horizontally or could instead divide into 2 x 2 squares? And for higher numbers with more irregular walls it might have to "jig-saw", using a mix of horizontal and vertical orientations to fit all of the edge conditions?
https://community.esri.com/thread/45459
proczell
proczell 2018-1-25
Yes, that is the general idea, although it should be noted that the room is not necesarilly make up op straight lines, it could look something like:
|\
| \
| \ /\
| \/ \
| |
| |
| |
|_______|
which may make it a bit more complicated. The thread you posted looks like is largely related to the same problems, although not in Matlab. Do you know any Matlab tools that may be helpful? If not I will certainely look through that thread and see if there may be anything helpful. Thanks!
My latest idea is in the lines of dividing the polygon with Delauney Triangulation and then try to divide the triangles into new cells again. But I don't know if it will be a good solution.
Thanks for your answer!
Walter Roberson
Walter Roberson 2018-1-25
In order to be able to divide an area into rectangles that are not infinitely small, all internal angles must be multiples of 90 degrees -- unless, that is, it is permitted to have space left over, in which case ideally you would prefer to minimize the space left over.
proczell
proczell 2018-1-26
That is true. Some space needs to be left over, but if the space is close to the "walls" it should be okay.
proczell
proczell 2018-1-26
Do you know if Matlab includes any kind of "fishnet" function to divide polygons?
Walter Roberson
Walter Roberson 2018-1-26
MATLAB itself does not have such a function.
I do not find such a function for MATLAB when I google, but perhaps different keywords would make a difference.
proczell
proczell 2018-1-26
I have not found any functions, from Matlab, Python or any other language I am familiar with. May have to try and make the function myself as it is absolutely necessary for my task.. Thanks for your help!
proczell
proczell 2018-1-26
I will check those out! Thank you.
proczell
proczell 2018-1-26
Since you have shown interest in helping me, I though I would post the current code, which seems to have a good potential.
area = 45.020;
sq_area = area/50;
side = sqrt(sq_area);
ylim = 5;
xlim = 4;
i = 1;
origin = [0 ;0]
L = origin;
figure
bOK = true
while(bOK)
L = [origin(1) ;origin(2)+side];
B = [origin(1) + side ;origin(2)];
R = [origin(1) + side ;origin(2) + side];
if L(1) < xlim
if L(2) < ylim
cubes{i} = [origin B R L origin]
curr_cube = cubes{i}
hold on
plot(curr_cube(1,1:end),curr_cube(2,1:end),'b')
origin = [L(1) ;L(2)]
i = i + 1;
else
cubes{i} = [origin B R L origin]
curr_cube = cubes{i}
hold on
plot(curr_cube(1,1:end),curr_cube(2,1:end),'b')
origin = [B(1) ;0]
i = i + 1;
end
else
bOK = 0;
end
pause(0.5)
end
This will swipe along the y-axis, but could easily be extended to a possibility for swiping along the x-axis. The final problem to solve is to make xlim and ylim dynamic according to the given room, a problem I think is highly solvable.
proczell
proczell 2018-1-27
Another update. This works as intended, but if anyone finds improvements or errors, please let me know.
clear all ;close all; clc
x = [0 18.01 18 14.51 0];
y = [0 0 0 0 0];
z = [0 0 5.0 2.5 24];
% Patch object
nlin = 200;
for i = 1:length(x)
if i == length(x)
if x(i) == x(1)
x_l(i,1:nlin) = x(i);
y_l(i,1:nlin) = linspace(z(i),z(1),nlin);
else
xd = x(i) + x(1); zd = z(i) + z(1);
m = (z(i) - z(1))/(x(i) - x(1));
x_l(i,1:nlin) = linspace(x(i),x(1),nlin);
y_l(i,1:nlin) = m*x_l(i,1:nlin) - m*x(i) + z(i);
end
else
xd = x(i) + x(i+1); zd = z(i) + z(i+1);
m = (z(i) - z(i+1))/(x(i) - x(i+1));
x_l(i,1:nlin) = linspace(x(i),x(i+1),nlin);
y_l(i,1:nlin) = m*x_l(i,1:nlin) - m*x(i) + z(i);
end
end
y_l = [y_l(1,1:end) y_l(2,1:end) y_l(3,1:end) y_l(4,1:end),y_l(5,1:end)];
x_l = [x_l(1,1:end) x_l(2,1:end) x_l(3,1:end) x_l(4,1:end) x_l(5,1:end)];
% hold on
figure
p = patch(x,y,z,'r')
figure
scatter(x_l,y_l)
% Compute area
verts = get(p, 'Vertices');
faces = get(p, 'Faces');
a = verts(faces(:, 2), :) - verts(faces(:, 1), :);
b = verts(faces(:, 3), :) - verts(faces(:, 1), :);
c = cross(a, b, 2);
area = 1/2 * sum(sqrt(sum(c.^2, 2)));
% Fishnet generation
area = 45.020;
sq_area = area/50;
side = sqrt(sq_area);
ylim = 5;
xlim = 4;
i = 1;
origin = [0 ;0]
L = origin;
x_2 = round(x_l,1);
xlim = max(x_l)
bOK = true
while(bOK)
L = [origin(1) ;origin(2)+side];
B = [origin(1) + side ;origin(2)];
R = [origin(1) + side ;origin(2) + side];
L_2 = round(R(1),1);
x_current = find(x_2==L_2)
for i = 1:length(x_current)
y_vals = y_l(x_current);
ylim = max(y_vals)
end
if L(1) < xlim
if L(2) < ylim
cubes{i} = [origin B R L origin];
curr_cube = cubes{i};
hold on
plot(curr_cube(1,1:end),curr_cube(2,1:end),'k')
origin = [L(1) ;L(2)]
i = i + 1;
else
cubes{i} = [origin B R L origin];
curr_cube = cubes{i};
hold on
plot(curr_cube(1,1:end),curr_cube(2,1:end),'k')
origin = [B(1) ;0]
i = i + 1;
end
else
bOK = 0;
end
pause(0.03)
end

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proczell
proczell
2018-1-25

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proczell
2018-1-27

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