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Activity Forums Adobe After Effects Expressions Question for Dan Ebberts

• Question for Dan Ebberts

Posted by on April 22, 2005 at 2:59 pm

Hi Dan, I love reading all your posts. You are a supplier of great knowledge.

I have many camera shots shooting straight down a cylinder. The cylinder has perspective lines run down its length. As well the cylinder has circles going around its circumference several feet apart down its length. The circles and lines give the cylinder perspective.

My problem is that the cylinder it only 20feet long and we need to add length to it to give it the point of Infiniti. If the camera were still we could just scale back the original to do this, but the camera dollys in. The focal length does not change. I was thinking I would animate stroke lines back to Infiniti and would attach the lines at the end of the real cylinder and track those point. But I need to move all of the circles as well to maintain the proper perspective. Do you have any ideas how I could write an expression to do this. As an addition I also have a few camera moves where the camera will ped up and dolly in.

Any info you can provide would be much appreciated.

Thanks ahead for any assistance Dan.

Graham

replied 19 years ago 3 Members · 2 Replies
• 2 Replies
• Dan Ebberts

April 22, 2005 at 3:38 pm

Wow. I don’t really have a clue as to how expressions would help you with this. I guess you’d have to do something like track the start and end point of each line so that you could have the beam effect extrapolate the line to the vanishing point. The vanishing point would have to be calculated based on the intersection point of at least two extended lines. I don’t know what you would do about the circles and the texture of the pipe. I think it would take you way longer to develop expressions for this than to brute force something by hand.

Maybe somebody else will have some ideas.

Sorry.

Dan

• Mylenium

April 22, 2005 at 5:51 pm

I would have to agree with Dan here. This is heavy 3D math if you use expressions and far to convoluted. Either try CC Cylinder with a grid as texture or use Trapcode’s 3D Stroke with its repeater function to create your structures. Both tools use AE’s camera and it shouldn’t be too difficult to line them up with your footage. Just make sure you are working in square pixel comps.

Mylenium

[Pour Myl

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