Help! How to make an object stay in a specific position (more info inside)

Report · Nov 08, 2018

I'm working on a project for a client, and I'd say that I have intermediate skills in AE. However, I'm having some issues with something that should be relatively simple but is proving not to be. I've included some screen shots to make it easier to understand.

Links to the screenshots: https://imgur.com/a/lXDfSFB

In the simple animation, there is a landfill, and a garbage truck drives up to it, dumps its trash, and drives away. The landfill is actually a very tall image that I drew in PS, and I made the "Camera" look up and down by using a null object and parenting it to the drawing. So it gives the illusion of looking up and down at the mountain of trash. (I know there are actual cameras in AE too, but I've not mastered those as yet)

When the "camera" reaches the bottom of the mountain of trash, I want to show another garbage truck rolling up and also dumping more garbage. This time, it dumps "500", as the narrator says "This landfill receives 500 tons of trash every day" at this point of the video. It would then roll away and continue into the next scene.

However, I'm having issues with making the garbage truck (which is made up of various layers and then pre-composed) appear at the right time. I think it's a matter of lining up the Null object's timing and that of the truck but I can't figure out how. The truck keeps appearing too early, as the camera is scrolling down, so it doesn't look right, and seems to "float" in mid air over the mountain of trash.

Is there a way that I can "pin" or make it stick to the ground image? I've tried making another null object, but it didn't work.

I'm really at a loss, and feeling frustrated. Would really appreciate some help. Thank you!

Report · Nov 08, 2018

I'm not 100% clear on what's going on from your images, but I think I get the idea.

Yes, using cameras and 3D objects makes this kind of job MUCH easier, and probably wouldn't take too much work to convert your current content in such a way.

But the issue should be fairly easy to fix in 2D as well. It seems to me that your issue is the animations you're applying to individual objects, to mimic a camera movement, are all falling out of sync. I would use a master Null to apply the vertical camera move. That way your camera move is entirely controlled by the position keyframes in that master null, and all the objects in your comp will follow it.

Remove all the animation on layers that mimic the camera move. Link all layers that need to move with the "camera" to that new master null.

Obviously if you have layers connected to another null already, don't connect the child layers. just connect the other null to your master null.

Use the master Null to generate the camera move. Then you should only need to animate your truck layers horizontally. They should always stay connected to their vertical position with the other layers.

Report · Nov 09, 2018

I addition to Andrew, it could be helpful to create a large precomp containing the landfill in it's overall size and putting the truck right where it should be (at the bottom). Then, it's only a matter of animation the y-position of this precomp.

Report · Nov 10, 2018

Hi Martin, thank you for replying too.

So you're suggesting to make a precomp for the landfill image, and then animating it using the Y position inside that same precomp? and then I would be able to make the trucks stay where I want them to?

Report · Nov 10, 2018

Hi Andrew, thanks for replying!

What is a Master null exactly? Does that mean that I attach all of the other elements (the garbage trucks, their trash, etc) to it?

I have only one null object in the composition, and I attached the long landfill image, so that I could give the effect of the camera looking up and down.

I got rid of the animation for the other layers like you said, but I found that the garbage trucks still floated in mid-air. I also tried adding another null object to make them "stay" in their places, but that didn't work out either.

I'm still not getting this done, and I feel a bit silly as I thought it was a relatively simple animation to make

Report · Nov 10, 2018

Here is a project file that demonstrates what I'm talking about (very crudely!) and I've also used Martin's suggestion of precomping the whole environment to better explain that process.

Let me know if this doesn't help you make sense of it.

Dropbox - truck example.aep

Report · Nov 11, 2018

Thank you SO much, Andrew! This example made it so much easier to understand what you were suggesting. I tried it, and it worked!!

I cannot thank you enough. You saved me hours of (even more) frustration and fumbling around.

Thank you once again!!