3D Surface plot with Cartesian coordinates

Hi,

I have a set of data that represents the (x,y) Cartesian coordinates of objects in an electric grid and another vector (z) that represents the voltage at the corresponding (x,y) coordinate. I have been trying to plot a heatmap/voltage contour map/surface voltage plot (bird's eye-view of (x,y) grid with magnitude of (z) at each point) but have been unable to do so successfully.

I imagine its just a question of getting the correct matrix inputs for the 'surf(X,Y,Z)' function.

if true
  % %the variations I've tried:
surf(busCoordsX, busCoordsY, busVoltsMesh);
view([0 90]);

 surf(busCoordsX, busCoordsY, busVoltsMesh');
view([0 90]);

 [X,Y] = meshgrid(busCoordsX, busCoordsY);
surf(X, Y, busVoltsMesh);
view([0 90]);
  end

I have created a version of the plot using stem3, but it does not achieve the correct view. I can supply coordinates and bus voltages, but hopefully what I'm doing wrong is obvious (and silly). Any help would be incredible.

Thanks!

[Youssef Khmou]

the instructions are correct, the wrong view is not explicit so far...

[Paul]

Hi Youssef,

Thanks for the response. Attached is my code, which should provide more details and below are the the results from my plotting attempts. It seems that more than one z-value is being assigned to each (x,y) coordinate, but I am not sure why this is happening.

Thanks!

Answer 1

[Youssef Khmou]

Paul,

I think reshaping will not give good results, however try these approaches,

1) Solution 1:

plot3(busCoordsX,busCoordsX,busVolts,'.')
grid on
view(-90,90)

Physical interpretation : The tension occurs when DX==DY !!!! ( to be verified).

2) Solution 2:

ZZ=diag(Z);
figure, surf(X,Y,ZZ)
shading interp
view(-63,76)

Physical interp : Random partition of the voltage in the plate .

Waiting for your answer.

Answer 2

[Paul]

Hi Youssef,

I am using my account at work, so different username. Thanks again for your suggestions. Solution 1 provides the same graph as a scatter3 plot (view at [0,90]), which is useful for verifying the circuit, but does not have the surface colormap.

For Solution 2, you wrote ZZ = diag(Z), and I initially tried this on the meshgrid(Z), but making a diagonal matrix from a 130x130x130 matrix locked up my computer. Doing diag(Z) on a 130x130 Voltage matrix returns a vector and that variable already exists. Am I interpreting your code incorrectly?

I have tried another method (code attached), using the 'griddata' function, and have a graph that somewhat does what I want, but it is not entirely correct. I am really stumped as to why surf(busCoordsX, busCoordsY, busVolts) does not work.

Thanks.

Answer 3

[Shivam Anand]

x=[32 20 67 1 98 34 57 65 24 82 47 55 8 51 13 14 18 30 37 39 10 33 21 26 38 81 83 60 95 22 17 5 72 46 99 52 12 25 96 29 70 85 43 69 19 78 97 31 89 53 2 91 48 71 61 15 36 84 94 50 11 80 6 7 49 74 9 88 40 79 27 68 73 64 63 59 86 23 35 58 45 28 100 42 93 87 16 90 41 66 54 92 77 4 62 76 75 56 3 44];
y=[96 75 24 9 83 49 27 77 3 23 17 31 40 13 7 52 51 21 98 47 64 79 78 91 44 16 15 100 84 99 63 68 70 30 54 76 97 73 33 5 88 8 71 66 62 25 60 42 72 45 18 11 28 59 89 65 10 55 69 81 12 26 20 95 87 41 74 50 93 22 43 90 14 34 82 35 56 38 80 32 1 57 6 36 37 61 29 58 2 48 4 46 67 53 92 86 94 19 39 85];
z=[55 31 11 45 83 36 86 49 15 57 42 46 8 94 88 47 54 81 98 41 32 35 56 85 9 89 37 60 23 62 67 100 78 76 73 80 10 20 68 34 77 93 1 63 53 12 22 99 91 40 84 24 33 3 43 19 92 97 6 82 64 25 26 79 95 4 44 58 5 21 70 29 65 87 96 90 51 14 18 2 72 28 71 39 52 7 27 59 50 61 48 30 66 69 17 13 74 16 75 38];
xlin = linspace(min(x), max(x), 100);
ylin = linspace(min(y), max(y), 100);
[X,Y] = meshgrid(xlin, ylin);
% Z = griddata(x,y,z,X,Y,'natural');
% Z = griddata(x,y,z,X,Y,'cubic');
Z = griddata(x,y,z,X,Y,'v4');
mesh(X,Y,Z)
axis tight; hold on
plot3(x,y,z,'.','MarkerSize',15)