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jump along bezier point

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Derek Dollahite
jump along bezier point
on May 12, 2010 at 7:20:19 pm

I've yet to find a solution for this, so I'm hoping someone here has encountered this problem. I basically have a camera positioned over a race track. The camera's point of interest follows a motion path along the track. The car uses the same motion path to follow the track. My problem occurs when the car almost gets to a bezier point on the motion path - it flips something (I can't tell that any orientation or position values flip) but the car flips horizontally along its center point. Any ideas what would cause this? Thanks for any help.


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Dave LaRonde
Re: jump along bezier point
on May 12, 2010 at 7:29:08 pm

It sounds like you've got some of your motion path's Bezier handles twisted around. Check 'em out.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Derek Dollahite
Re: jump along bezier point
on May 12, 2010 at 7:51:59 pm

Thanks for the reply - I think you're right, it is a twist in the bezier handles, but I'm not sure how to correct it. It's a closed path copied and pasted from illustrator. So in the illustrator path some bezier handles are on the outside of the path and some are on the inside. When pasting it as a motion path it will give me a few key frames with roving key frames between. Any changes I try to make to the bezier handles on the key frames totally throw things off...Do you know of any adjustments I can make to the path in illustrator before bringing in to AE or is there another kind of interpolation method in AE that could fix it. Thanks again.




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Dave LaRonde
Re: jump along bezier point
on May 12, 2010 at 9:43:03 pm

q[Derek Dollahite] "...do you know of any adjustments I can make to the path in illustrator before bringing in to AE or is there another kind of interpolation method in AE that could fix it...."

I don't know much about Illustrator so for me the fix lies in AE, and it won't be much fun. Any adjustments you make will have to affect everything you've done so far: there's no avoiding that.

To make it a no-brainer, double-click on the Illustrator layer with the path, opening it in the footage window. Hit the v key to make sure you've got the proper cursor selected. Locate a suspect keyframe and magnify the layer to see a vertex and bezier handle. You can move the layer around in the window (won't affect the comp) by holding the h key while you drag in the footage window.

When you're magnified enough, you can untwist the handle.

An alternative: locate a suspect keyframe. Hit the g key until the cursor turns into a v shape. Click on the mask vertex to make it linear. Click on it again to make it Bezier, and adjust handles as necessary.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Alperen T. Ayhan
Re: jump along bezier point
on May 12, 2010 at 9:27:57 pm

If you parent your camera to null object ( must be switched to a 3D layer) it will be very easier for you. All you need is just a null object..

Alperen T. AYHAN
http://www.sinamasal.com
Always cinema...


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Derek Dollahite
Re: jump along bezier point
on May 12, 2010 at 10:47:25 pm

How would parenting to a null help - it still moves along the same path and still flips at the same points?
I've looked very closely at the bezier handles and it actually doesn't look like they are twisted...not sure what's going on. Thanks for the help.




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Alperen T. Ayhan
Re: jump along bezier point
on May 12, 2010 at 11:02:33 pm

first reset the camera or delete it create a new one. then layer/new/null obj. then switch it to 3D. parent camera to the null.



and then whatever you have done before (like applying motion path..) to your old camera, this time apply to the nulls behaviour. that's all..

Alperen T. AYHAN
http://www.sinamasal.com
Always cinema...


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Derek Dollahite
Re: jump along bezier point
on May 12, 2010 at 11:29:49 pm

Yep - i know how to parent the camera to the null and paste the motion path to the null - but the flips are within the motion path. Regardless of whether the path is on the camera's point of interest or the Null's postion property with the camera parented, it still flips at the same point along the path. How does putting the path on the Null change the problem with the actual path?





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Alperen T. Ayhan
Re: jump along bezier point
on May 13, 2010 at 12:05:36 am

sorry sorry, I've taken your time.. As I said before my English isn't so good. I've tried to do a work similar to your description and I did not have any problems in both way(with null and without null) Then I realized, I've missed something in your first post.. I think Dave's reply gives the answer, you need to check your path.. sorry again..

Alperen T. AYHAN
http://www.sinamasal.com
Always cinema...


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Derek Dollahite
Re: jump along bezier point
on May 13, 2010 at 1:33:07 am

Alparen, no need to apologize - thanks for trying to help! I'll keep fiddling with the path.



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Derek Dollahite
Re: jump along bezier point
on May 13, 2010 at 2:40:23 am

I've created a simplified version of the problem...I probably didn't explain enough in my first post. The problem is specifically when use "auto orient to path" is used. If you scrub the timeline with the solid selected you'll see the center point flip just before it gets to some of the bezier points. Again, thanks for taking the time.

http://www.coloringbookstudio.com/old/motion_path_problem.zip





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Alperen T. Ayhan
Re: jump along bezier point
on May 13, 2010 at 2:33:29 pm

I've looked at the project file and now trying to figure it out. I think there's something wrong with only path.. I've played some of keyframes and one of them is now good.. If it work for all, I'll send the new one..

Alperen T. AYHAN
http://www.sinamasal.com
Always cinema...


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Derek Dollahite
Re: jump along bezier point
on May 13, 2010 at 7:51:07 pm

Thanks for looking. What did you do to the keyframe to make it work? Seems like there has to be a better way to do what I'm trying to achieve.



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Alperen T. Ayhan
Re: jump along bezier point
on May 13, 2010 at 10:41:11 pm

there's something wrong with keyframes of motion path.. not about timing, "solid" flips every keyframe to opposite side. I do not know why.. Then I have drawn a new copy of your motion path, it worked correctly. I didn't understand the reason.. I think you need to do it from the beginning.

Alperen T. AYHAN
http://www.sinamasal.com
Always cinema...


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