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Why does COMSOL consistently enforce smoothing in 2D surface rendering?
Posted Feb 16, 2024, 12:50 p.m. EST Results & Visualization Version 6.1 2 Replies
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Lately, I've been utilizing the atan2 function to represent the azimuthal angle of a vector. I've noticed that the atan2(Y,X) function performs well even when Y is close to zero. However, when employing a cyclic color table to visualize the azimuthal angle ranging from -180 degrees to +180 degrees, the 2D surface tool renders the abrupt transition from -180 degrees to +180 degrees as a gradual transition in between. To elaborate further, originally, it should display as a single red color according to the cyclic color table, but it consistently appears as a rainbow color in the transition zone. How can I address this issue? An example file is also provided.
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The problem is that when you evaluate in the mesh nodes that are exactly at Y=0, the result must be either +180 or -180. Inside one of the adjacent elements (either up or down) there will then be an apparent gradient of almost 360 degrees.
You can avoid this artefact by evaluating inside the elements, for example by using an expression like gpeval(4,atan2(Y,X)/pi*180)
-------------------Henrik Sönnerlind
COMSOL
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Dear Henrik,
Thank you for your valuable professional input regarding the gpeval function.