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Difficulty finding center for anchor point

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Christian Wheel
Difficulty finding center for anchor point
on Feb 6, 2010 at 5:31:52 am

I have a PNG image that I've imported into AE that contains a circle in it.

The circle is off-center in the image, but I want to rotate the image, using the circle as the center.

Obviously I need to get the anchor point into the center of the circle to make it work.

Problem is, I can't seem to find the dead center of the circle. Every time I think it's positioned correctly, I test my rotation, and I can see the circle "wobble" indicating that the anchor point isn't set properly.

Is there an easy way to find the dead center of the circle? Or am I just stuck doing trial-and-error?


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Christopher R. Green
Re: Difficulty finding center for anchor point
on Feb 6, 2010 at 10:04:32 am

Hi. There are a few ways to do this.
One way to do this is to use my "Separate_Masks_in_Layers" script. It has a feature which calculates centers based on the masks you give it. So you could theoretically put a mask which matches the circle on the image, then run the script on the layer and let it calculate the center based on the mask. One caveat, though: It won't run if there is only one mask on a layer, so you could do [Layer>Mask>New Mask] first, making a mask for the whole thing, then make your circular mask (using the Ellipse Tool, perhaps) and run the script, afterward deleting both the "main mask layer", and the circular mask in the remaining layer.
My ReAnchor_Selected_Layers script is for placing single-vertex-masks quickly on layers on which it is easy or perhaps not-so-crucial as far as where the new anchor points go. "Eyeballing" this kind of thing can be frustrating, because you cannot, for example, free-transform a mask and move guides to the center of the mask (which becomes visible when free-transforming); the two things -- free transforming a mask, and dragging a guide to where you want -- cannot happen at the same time. You can zoom way the heck in, though, and try to find the exact pixel on which to pop a singe-vertex-mask, then run the ReAnchor script.

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serj bato
Re: Difficulty finding center for anchor point
on Feb 8, 2010 at 10:39:57 am

or you can do this:

1. Create a solid layer on top of your image(keyboard shortcut- ctrl-Y)
2. Make your solid layer opacity to 50 percent
3. click the Q several times to choose the elliptical mask. Assuming you solid layer is selected, drag it across the viewer window with while click holding the shift key to create a perfect circle. Don't overdo it & keep the elliptical mask whre you can view it at 100 percent.
4. Click the aspostrophe key(or the key beside the semicolon key,to the right) to activate the Action safe in your viewer. When activated, you can use the crosshair at the center a a reference.
5. Double click your mask, now your mask will have a crosshair at its center.
6. Position your mask in the middle of the viewer aligning its crosshair to the crosshair of the action safe.
7. Now drag your image to properly place it in the middle of the viewer using the solid layer as reference. scale your image to properly fit the size of the solid layer & properly aligning it to the solid layer.
8. Now click Y in your keyboard. Notice the selection tool(or your cursor) changes its appearance(basically your selection tool with a circle attached to it). It's now the Pan Behind Tool.Its a tool for repositioning the anchor point without changing the position properties.
When doing so, notice a red chrosshair appears in the viewer. Using the Pan Behind Tool, select & drag the red crosshair in the middle of the viewer using the crosshair of the action safe as guide.
9. Click V to change the tool back to Selection Tool. Now you have your proper ancor point on you image.

Hope it helps.

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