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Continuous Cyclic Color Table Plot
Posted 21.07.2016, 03:48 GMT-4 Acoustics & Vibrations, Results & Visualization Version 5.2 1 Reply
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Hi,
I am trying to visualize the phase of an acoustic mode. I calculate the phase of my pressure field via: atan2(real(p),imag(p)) where p is the acoustic pressure.
I rescale the phase to a -180 to +180 degree interval and plot it as a surface using the cyclic colortable. The result looks fine, except that there are discontinuities in the surface plot where the phase jumps from -180 (red) to +180 (red) between cells. The color of the surface plot changes through all of the intermediate values producing 1 cell wide "rainbow bands" throughout the surface plot.
Is there a way to make a continuous cyclic color table plot? i.e. one where between cells with -180 (red) and +180 (red) the color stays red?
thanks
I am trying to visualize the phase of an acoustic mode. I calculate the phase of my pressure field via: atan2(real(p),imag(p)) where p is the acoustic pressure.
I rescale the phase to a -180 to +180 degree interval and plot it as a surface using the cyclic colortable. The result looks fine, except that there are discontinuities in the surface plot where the phase jumps from -180 (red) to +180 (red) between cells. The color of the surface plot changes through all of the intermediate values producing 1 cell wide "rainbow bands" throughout the surface plot.
Is there a way to make a continuous cyclic color table plot? i.e. one where between cells with -180 (red) and +180 (red) the color stays red?
thanks
1 Reply Last Post 21.07.2016, 11:55 GMT-4
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Posted:
8 years ago
Hi,
The problem lies in the interpolation between -180 and 180 within the elements where the jump is. You could try to force the value to be 180 where the phase has a large gradient.
Here is a suggestion in that direction (not tested thogh)
Create three variables:
phase: atan2(real(p),imag(p))*180/pi
phase_gradient: sqrt(d(phase,x)^2+d(phase,y)^2+d(phase,z)^2)
phase_cyclic: if(phase_gradient>100,180,phase)
The limit on the gradient (here 100) must of course be tuned to your actual spatial phase gradient so that it only captures the jumps.
Now you can plot phase_cyclic, and hopefully the results should look better.
Regards,
Henrik
The problem lies in the interpolation between -180 and 180 within the elements where the jump is. You could try to force the value to be 180 where the phase has a large gradient.
Here is a suggestion in that direction (not tested thogh)
Create three variables:
phase: atan2(real(p),imag(p))*180/pi
phase_gradient: sqrt(d(phase,x)^2+d(phase,y)^2+d(phase,z)^2)
phase_cyclic: if(phase_gradient>100,180,phase)
The limit on the gradient (here 100) must of course be tuned to your actual spatial phase gradient so that it only captures the jumps.
Now you can plot phase_cyclic, and hopefully the results should look better.
Regards,
Henrik