Visualization of (continuous) secondary source contour by polygon

[spors]

import numpy as np
import sfs

xs = [0, 2, 0]
grid = sfs.util.xyz_grid([-2.5, 2.5], [-2.5, 2.5], 0, spacing=0.02)
omega = 2*np.pi*1000

x0, n0, a0 = sfs.array.circular(200, 1.5)
d = sfs.mono.drivingfunction.wfs_2d_line(omega, x0, n0, xs)
a = sfs.mono.drivingfunction.source_selection_point(n0, x0, xs)
twin = sfs.tapering.tukey(a, 0.3)
p = sfs.mono.synthesized.generic(omega, x0, n0, d * a0 * twin, grid)

sfs.plot.soundfield(p, grid, xnorm=[0, 0, 0], vmin=-1.5, vmax=1.5)
sfs.plot.secondarysourcecontour_2d(x0, a)
sfs.plot.virtualsource_2d(xs)

[trettberg]

Two observations:

• The contour has a gap.
• The region of active sources is not symmetric. (Easier to see with few speakers, 16 or so).

[mgeier]

I guess this needs a closed parameter like sfs.array.weights_midpoint()?

[mgeier]

Possible fix for the second point made by @trettberg above: instead of line segments from one secondary source to the next, we should use line segments from halfway from the previous source to the current source to halfway to the next source. Again, the implementation could be similar to sfs.array.weights_midpoint().

[spors]

I have fixed the issue regarding the gap and the region of active secondary sources:

import numpy as np
import sfs
import matplotlib.pyplot as plt

xs = [5, 0, 0]

x0, n0, a0 = sfs.array.circular(20, 1.5)
a = sfs.mono.drivingfunction.source_selection_point(n0, x0, xs)

plt.figure(figsize=(10, 10))
sfs.plot.secondarysourcecontour_2d(x0, a)
sfs.plot.loudspeaker_2d(x0, n0, a, size=0.2)
sfs.plot.virtualsource_2d(xs)
plt.axis([-5.2, 5.2, -5.2, 5.2])

[mgeier]

This should be ax.add_collection(lc)

[mgeier]

Now it looks like the array is always closed, even if we don't want it to be:

sfs.plot.secondarysourcecontour_2d([(0, 0), (1, 1), (2, 1), (3, 0)],
                                   [False, True, True, False])
plt.axis('equal');

[hagenw]

Have the secondary sources to be connected by a line?
Under Matlab I solved the gap issue by using only points for plotting secondary sources. If the distance between them becomes very small then they appear as a line. If the distance is not small, points have the advantage that you still are able to see the actual distance.