How to create contour plot to show height?
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I want to create a countour plot such that my x axis and y axis are the coordinates of the plane and my z axis is height. I want to creat a 2b plot (contour) such that my height is differentiated with color. My z value has no relation with xy value other that the first value of z is corresponding to the cobination of first two values of x and y.
For example my x, y and z vectors are:
AAA=1:1:1000;
BBB=1:1:1000;
CCC=2:2:2000;
3 个评论
DGM
2022-3-18
if there's no correlation between Z and X,Y, then you don't have a meaningful description of a 2D dataset.
If the x,y,z vectors are correlated, but scattered, then use griddata() to create gridded data that's compatible with what contour() expects.
Muhammad Qaisar Fahim
2022-3-18
DGM
2022-3-18
Okay, yeah. That's just scattered data. Walter's suggestion looks pretty good.
采纳的回答
You can always try just using griddata()
S = load('scattered.mat'); % load scattered data
n = 100;
x = linspace(min(S.x),max(S.x),n);
y = linspace(min(S.y),max(S.y),n);
[xg yg] = meshgrid(x,y); % create new grid
zg = griddata(S.x,S.y,S.z,xg,yg); % interpolate scattered data to grid
contour(xg,yg,zg) % now you can use contour(), contourf(), surf(), etc
8 个评论
Muhammad Qaisar Fahim
2022-3-19
Are you sure you want an actual contour plot?
S = load('scattered.mat'); % load scattered data
n = 100;
x = linspace(min(S.x),max(S.x),n);
y = linspace(min(S.y),max(S.y),n);
[xg yg] = meshgrid(x,y); % create new grid
zg = griddata(S.x,S.y,S.z,xg,yg); % interpolate scattered data to grid
contourf(xg,yg,zg)
figure
pcolor(xg,yg,zg)
shading flat
Or maybe you want something else?
figure
S = load('scattered.mat'); % load scattered data
scatter3(S.x,S.y,S.z,10,S.z,'filled')
Muhammad Qaisar Fahim
2022-3-21
Muhammad Qaisar Fahim
2022-3-21
Sam Chak
2022-3-21
You better share/attach the spatial data longitude A, lattitude B, elevation C (road height) here in the comments and edit your original post, so that you can get the proper help that you want.
You also need to confirm if the following conversion gives the geometry of the road.
x = (6371).*cos(B).*cos(A);
y = (6371).*cos(B).*sin(A);
scatter(x, y)
So you basically want variable-color lines. There are two basic ways to do that.
First, you could use a very dense scatter plot to create pseudolines. This is the simple way, and the data doesn't need to be ordered.
cmap = parula(64);
N = 1000; % how many points to plot?
x = linspace(0,10,N); % a straight line
y = linspace(0,10,N);
z = sin(linspace(-pi/2,7*pi/2,N)); % sinusoidally-varying z-height
h = scatter(x,y,10,z,'filled');
colormap(cmap);
colorbar
Alternatively, you can use a surf() plot. This will actually create lines, so the data needs to be ordered.
cmap = parula(64);
N = 100; % how many points to plot?
x = linspace(0,10,N); % a straight line
y = linspace(0,10,N);
z = sin(linspace(-pi/2,7*pi/2,N)); % sinusoidally-varying z-height
h = surf([x(:) x(:)],[y(:) y(:)],[z(:) z(:)]);
set(h,'facecolor','none','edgecolor','interp');
set(h,'linewidth',3); % make it fat so it's easier to demonstrate
view(2); % only show 2-D view
colormap(cmap);
colorbar
That said, I don't know how exactly this data is arranged -- how dense it is, etc. It may become complicated if the points are relatively sparse and unordered.
DGM
2022-3-21
Oh. Well it doesn't make much sense spending time and confusion here then. Thanks for the heads up.
更多回答（1 个）
Walter Roberson
2022-3-18
0 个投票
2 个评论
Muhammad Qaisar Fahim
2022-3-18
编辑：Walter Roberson
2022-3-19
Walter Roberson
2022-3-19
The first parameter to tricontour() needs to be the xy coordinates, each row being an x y pair.
The second parameter to tricontour() needs to be the triangular connectivity data.
You might want to use https://www.mathworks.com/help/matlab/ref/delaunaytriangulation.html and extract the Points and ConnectivityList properties of the result.
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