UI sprite distorted while rotated

[Mr_Jigs]

Using unity 5.1 I have a sprite in the UI that is being distorted when the empty parent object is being rotated. The rotation is provided by a script. See attached movie for the particular distortion effect and the attached screenshot for the hierarchy. I do notice that the distortion is cyclic and at it’s worst when the rotation is at about 45 degrees.

I have tried sprites at several sizes including one made the same size as the recttransform window. There are no rotation or scaling transforms on the empty parent (other then the rotation around z) or the child containg the sprite.

I have seen this before when making an ios app. the distortion then was caused by some layout constraints. When I removed them the distortions disappeared. I am not sure on how to remove any possible constraints in the new UI

2268053–151939–sample.mov.zip (811 KB)

[Mr_Jigs]

When I tried to create a demo project with just the image the distortion did not appear. So I suspect it is indeed to do with the constraints in the UI hierarchy above it. Truing to find it now.

[Mr_Jigs]

Turning of the “pixel perfect” option in the canvas component settings at the very top level UI hierachy object made the distortions go away.

Once you know where to look the manual actually has an entry for it:
“Enabling pixelPerfect can make elements appear sharper and prevent blurriness. However, if many elements are scaled or rotated, or use subtle animated position or scaling, it may be advantageous to disable pixelPerfect, since the movement will be smoother without.”

I guess that is legalese for no distortion