# Two 3D surface plots where colors represent same value on both surfaces

How do I draw two 3D surface plots where the surface patch colors have consistent meaning?

Hope this makes sense …

Currently, I’m just doing two plot_surface commands, each of which has cmap=cm.jet. The two surfaces have different shapes and sizes and have different highest/lowest points. It seems that the colormap is automatically normalised to the highest/lowest values for each surface independently (e.g. the highest point on both surfaces is red, even though they are different values). Instead, I want the same color to represent the same value on both surfaces.

Any ideas will be appreciated. Perhaps there’s a way to force the colormap to be normalised to a specified range of values?

from mpl_toolkits.mplot3d import Axes3D
from matplotlib import cm
import matplotlib.pyplot as plt
import numpy as np
fig = plt.figure()
ax = Axes3D(fig)
X = np.arange(-5, 5, 0.25)
Y = np.arange(-5, 5, 0.25)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X2 + Y2)

Z = 5*np.sin®
ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.jet)

Z = np.cos®
ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.jet)

plt.show()

What you need to do is to share a normalizer among different surface
plots (this is not just for surface plot, but for all (as far as I
know) color representation that uses colormaps). Note that "norm" can
also be a keyword argument.

Regards,

-JJ

Z1 = 5*np.sin(R)
s1 = ax.plot_surface(X, Y, Z1, rstride=1, cstride=1, cmap=cm.jet)
mynorm = s1.norm

Z2 = np.cos(R)
s2 = ax.plot_surface(X, Y, Z2, rstride=1, cstride=1, cmap=cm.jet)
s2.set_norm(mynorm)

mynorm.vmax = max(Z1.max(), Z2.max())
mynorm.vmin = min(Z1.min(), Z2.min())

···

On Fri, Oct 2, 2009 at 5:44 PM, Sammo <sammo2828@...287...> wrote:

How do I draw two 3D surface plots where the surface patch colors have
consistent meaning?

Hope this makes sense ...

Currently, I'm just doing two plot_surface commands, each of which has
cmap=cm.jet. The two surfaces have different shapes and sizes and have
different highest/lowest points. It seems that the colormap is automatically
normalised to the highest/lowest values for each surface independently (e.g.
the highest point on both surfaces is red, even though they are different
values). Instead, I want the same color to represent the same value on both
surfaces.

Any ideas will be appreciated. Perhaps there's a way to force the colormap
to be normalised to a specified range of values?

from mpl_toolkits.mplot3d import Axes3D
from matplotlib import cm
import matplotlib.pyplot as plt
import numpy as np
fig = plt.figure()
ax = Axes3D(fig)
X = np.arange(-5, 5, 0.25)
Y = np.arange(-5, 5, 0.25)
X, Y = np.meshgrid(X, Y)
R = np.sqrt(X**2 + Y**2)

Z = 5*np.sin(R)
ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.jet)

Z = np.cos(R)
ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.jet)

plt.show()

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