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soliloqueen
soliloqueen
Participant
August 5, 2022
Question

Polar Coordinates not reversible

  • August 5, 2022
  • 1 reply
  • 681 views

Okay, so here's a gripe I've been running into recently: Polar coordinates behavior is weird. It doesn't "unwrap" about the center of the layer. If I stack two polar coordinates on top of each other, one rectangular to polar and one polar to rectangular, I should get an unaltered image, but I don't. This changes depending on the order of the two polar coordinates effects, which it doesn't feel like it should? This has been bothering me for like 8 years now, and I end up bouncing out to photoshop and back...Is this correct behavior? it seems like a bug, but if it is, it's a very old one...

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1 reply

R
Community Expert
Rick GerardCommunity Expert
Community Expert
August 5, 2022

Why are you not keyframing the interpolation values to reverse the effect? That would unwrap the effect. Rectangular to polar and Polar to rectangular are two completely different algorithms. Polar to Rectangular takes the layer center and moves it counterclockwise to the top center of the layer. Rectangular to Polar takes layer center and pulls it down halfway between layer center and layer bottom. There is no reason that one would reverse the other.

 

 

If you add another copy, or Pre-compose and apply the effect, you are applying an effect on top of an effect. I don't know any effect that can undo the result of a duplicate of that effect.

 

One more point, you can copy and paste an image file, drag it, or use the Toolbar to embed images instead of uploading them. It's a pain to open the uploaded images to see what you are trying to share. Also, cropped screenshots that do not show the modified properties (uu) of the problem layer are useless for diagnosing problems because you cannot see what is happening in the comp. It would help if we understood what you were trying to accomplish in your design.

soliloqueen
soliloqueenAuthor
Participant
August 5, 2022
quote

Why are you not keyframing the interpolation values to reverse the effect? That would unwrap the effect. Rectangular to polar and Polar to rectangular are two completely different algorithms. Polar to Rectangular takes the layer center and moves it counterclockwise to the top center of the layer. Rectangular to Polar takes layer center and pulls it down halfway between layer center and layer bottom. There is no reason that one would reverse the other.

 

 

If you add another copy, or Pre-compose and apply the effect, you are applying an effect on top of an effect. I don't know any effect that can undo the result of a duplicate of that effect.

 

One more point, you can copy and paste an image file, drag it, or use the Toolbar to embed images instead of uploading them. It's a pain to open the uploaded images to see what you are trying to share. Also, cropped screenshots that do not show the modified properties (uu) of the problem layer are useless for diagnosing problems because you cannot see what is happening in the comp. It would help if we understood what you were trying to accomplish in your design.


By @Rick Gerard

i need to apply in effect in polar space that will be displayed in retangular space, and i need the mapping from rect to pol and back to be the same..."there is no reason one should reverse the other." there is every reason! this is like saying there's no reason two inverts should reverse each other... rect to polar and polar to rect are supposed to be the same operation in two different directions.

R
Community Expert
Rick GerardCommunity Expert
Community Expert
August 5, 2022

Polar coordinates use two completely different calculations. If the effect has been applied, adding the effect again only adds to the effect. If you wanted to unwrap a circle created by Polat to Rectangular, you would have to invert the math, not use an entirely different calculation. You completely misunderstand how the math works in the two operations and are not following the render order.

 

Rectangular to Polar takes the original contents of any layer and converts them to a circle by pulling down on the top center of the layer and bending the sides. The distortion is based on layer size, not comp size. The layer size for a shape layer is comp width. Applying Polar coordinates to a shape layer that is 1000 X 1000 is going to look completely different than applying it to a solid that is 1000 X 1000. To make the distortion look identical on a shape layer, you must change the comp size to 1000 X 1000. 

 

When you apply two copies of Polar Coordinates, the second copy is working no longer working on the original shape of the layer, so you can't undo the layer to the original shape. It's as simple as that. 

 

One more thing. The Polar Coordinates effects does not respect transparency, it only work on layer size.

 

 

 

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