Plotting terrain data with matplotlib plot_surface

Question

I'm trying to plot terrain elevation data with matplotlib. I build up a nx3 numpy array, with each row containing the x, y, z coordinates of my points (they're regularly spaced in a grid on the x, y plane). I am attempting to plot it with this code:

fig = plt.figure()

ax = fig.gca(projection='3d')

print desiredData[:,0]

surf = ax.plot_surface(desiredData[:,0], desiredData[:,1],
                       desiredData[:,2], rstride =1,
                       cstride = 1, cmap=cm.jet,
                       linewidth = 0, antialiased = False)

plt.show()

but I'm getting this error:

Traceback (most recent call last):
   File "gisConvert.py", line 203, in <module>
linewidth = 0, antialiased = False)
File "C:\Python27\lib\site-packages\mpl_toolkits\mplot3d\axes3d.py", line 663,
in plot_surface
rows, cols = Z.shape
ValueError: need more than 1 value to unpack

What am I doing wrong?

user225312 · Accepted Answer · 2010-12-20 07:15:07Z

4

As the error suggests,

ValueError: need more than 1 value to unpack

You are using a 1D-array but plot_surface expects 2D arrays for X, Y and Z.

And that is why you get the ValueError.

answered Dec 20, 2010 at 7:15

user225312

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3 Comments

Justin Peel Over a year ago

Quite right. OP, check out the examples/mplot3d directory for some good examples of how to use plot_surface.

Ben Jones Over a year ago

So instead of the nx3 array I should have 3 mxp arrays? I assume that's so matplotlib can identify the structure of the data?

user225312 Over a year ago

@Ben Jones: You need 2D arrays for the co-ordinates, yes.

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