具有透明背景的 mplot3d 动画 [英] mplot3d animation with transparent background

问题描述

我想使用 matplotlib 生成一些具有透明背景的 gif.我尝试了不同的选项，但无法获取具有透明背景的文件.使用当前设置，我得到了第一帧，但不是其他帧.以下是我的代码

I want to generate some gifs with transparent background using matplotlib. I tried different options but I can't get my files with transparent background. With the current setup I get the first frame like that but not the rest. The following is my code

from __future__ import division
from numpy import pi, sin, cos, mgrid
from scipy.special import jn, jn_zeros
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib import rcParams


# In Windows the next line should provide the full path to convert.exe
# since convert is a Windows command
rcParams['animation.convert_path'] = "C:\Program Files\ImageMagick-6.9.3\convert.exe"
rcParams['savefig.transparent'] = True
rcParams['savefig.dpi'] = 130
rcParams['savefig.pad_inches'] = 0
plot_args = {'rstride': 1, 'cstride': 1, 'cmap':"RdYlBu",
             'linewidth': 0.5, 'antialiased': True, 'color': '#1e1e1e',
             'shade': True, 'alpha': 1.0, 'vmin': -1, 'vmax':1}


def data_gen(num):
    ax.cla()
    m, n = 1, 2
    lam = jn_zeros(m, n)[-1]
    dt = 2*pi/(30*lam)
    z = cos(m*t)*jn(m, lam*r)*sin(lam*num*dt)
    surf = ax.plot_surface(x, y, z, **plot_args)
    ax.view_init(elev=30, azim=45)
    ax.set_xlim(-0.6, 0.6)
    ax.set_ylim(-0.6, 0.6)
    ax.set_zlim(-1, 1)
    plt.axis("off")
    return surf


r, t = mgrid[0:1:20j, 0:2*pi:40j]
x, y = r*cos(t), r*sin(t)
fig = plt.figure(facecolor=None)
ax = fig.add_subplot(111, projection='3d')
ani = animation.FuncAnimation(fig, data_gen, range(30), blit=False)
ani.save("Drum vibration mode.gif", writer='imagemagick')

结果如下(如果你点击它，你可以看到只有一帧是透明的)

That gives as a result (if you click on it, you can see that just one frame is transparent)

问题:有没有办法使用 mplot3d 获得具有透明背景的动画?

Question: Is there a way to get the animation with transparent background using mplot3d?

推荐答案

我认为这确实是一个错误.但是，如果您更关心结果而不是到达那里的方式，那么下面的工作就可以了.您可以单独保存每个图像，而不是调用动画，然后调用 imageMagick 将它们转换为动画 gif.请参阅下面的代码并注意 convert.exe 的参数.

I think it's really a bug. However, if you rather care about the result than the way to get there, the following would do the job. Instead of calling animation, you can save each image separately and then call imageMagick to convert them to an animated gif. See the code below and mind the arguments to convert.exe.

from __future__ import division
from numpy import pi, sin, cos, mgrid
from scipy.special import jn, jn_zeros
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt

from matplotlib import rcParams
import subprocess


# In Windows the next line should provide the full path to convert.exe
# since convert is a Windows command
path_to_convert =  "C:\Program Files\ImageMagick-6.9.3\convert.exe"
#rcParams['animation.convert_path'] = path_to_convert
rcParams['savefig.transparent'] = True
rcParams['savefig.dpi'] = 130
rcParams['savefig.pad_inches'] = 0
plot_args = {'rstride': 1, 'cstride': 1, 'cmap':"RdYlBu",
             'linewidth': 0.5, 'antialiased': True, 'color': '#1e1e1e',
             'shade': True, 'alpha': 1.0, 'vmin': -1, 'vmax':1}


def data_gen(num):
    ax.cla()
    ax.clear()
    m, n = 1, 2
    lam = jn_zeros(m, n)[-1]
    dt = 2*pi/(30*lam)
    z = cos(m*t)*jn(m, lam*r)*sin(lam*num*dt)
    surf = ax.plot_surface(x, y, z, **plot_args)
    ax.view_init(elev=30, azim=45)
    ax.set_xlim(-0.6, 0.6)
    ax.set_ylim(-0.6, 0.6)
    ax.set_zlim(-1, 1)
    ax.axis("off")
    fig.patch.set_visible(False)
    ax.patch.set_visible(False)
    ax.set_axis_off()
    ax._axis3don = False
    return surf


r, t = mgrid[0:1:20j, 0:2*pi:40j]
x, y = r*cos(t), r*sin(t)
fig = plt.figure(facecolor=None, frameon=False)
ax = fig.add_subplot(111, projection='3d')
for i in range(30):
    data_gen(i)
    plt.savefig("drum_{n:02d}.png".format(n=i), transparent=True,  frameon=False)
    print i, 

args = [path_to_convert, "-delay", "10", "-loop" , "0", "-dispose", "Background", "drum_*.png", "output.gif"]
subprocess.call(args, shell=True)
subprocess.call(["del", "/Q", "drum_*.png"], shell=True)
print "\ndone"

请注意对 imageMagick 和删除命令的调用可能是系统相关的.此脚本已在 Windows 8 下使用 imageMagick 7.0.3 (Q16) 进行测试.

Mind that the calls to imageMagick and the delete command might be system dependend. This script has been tested with imageMagick 7.0.3 (Q16) under Windows 8.

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