Creating a path behind 3d null object

Report · Nov 28, 2019

First time poster here, hello everyone.

I am fairly new to After Effects and have only used the basic functions before.

I create route profiles for our running community and have been making the path in Google Earth Studio and the null layers (for location information etc) in After effects. But, I'm looking to animate the path now.

The problem that I'm facing is that I cannot figure out how to draw a 3d path that decays behind a null layer that follows the route profile. I have animated a dot that follows the route profile path, but cannot find anywhere how to make the actual path. I can on a '3d' layer with an X and Y axis, but as soon as points need a Z axis I run into this problem.

Here's an example of what I'm working on. Behind the floating shoe is where I'm trying to make the path... https://www.youtube.com/watch?v=Y5Q_dmcxMnM

And here's an example using the path from GE... https://www.youtube.com/watch?v=AiNggPL_2UE

Thanks in advance for any help.

Regards,

Daniel

Report · Nov 28, 2019

you must do 3D Camera Tracker to your footage and link your path to some 3D point,

leasr more about camera tracker here https://helpx.adobe.com/after-effects/atv/cs6-tutorials/3d-camera-tracker.html

Report · Nov 28, 2019

Thanks OussK,

I have already created the 3D camera (well GE did when I ran the script file). So that data is there and I can link objects to null layers linked to the 3D cam. But, I can't figure out how to create a path that'll follow the null layer that follows the created route.

Here's a video link of the After Effects project with the layers working together. https://youtu.be/mMGiwT7IrWw

I hope this explains it a bit better on what I'm trying to do. I know there must be a simple way of doing it. But, I cannot find it anywhere.

Also, if I use the path tool to follow the shape around, it doesn't have the Z coordinate. I can make the whole path go up and down, but not the individual points. That's why I animated the null layer (linked to the first point) and then was hoping to create a shape layer that I could stroke the created path of the null layer.

Thanks again, I appreciate any help!

Report · Nov 28, 2019

Creat New shape layer with path stroke and trim path, than copy the keyframes from the Null and paste it over the path (inside the shape layer) than use the trim effets to creat the path animation

Report · Nov 28, 2019

Thanks.

It seems to be on the right track, but the path tool seems to ignore any Z axis data, so is on a flat plane. So, the two don't quite match up. The shoe is either above or below the line. The intended path of the moving null layer moves on 3 axis, but this one seems to only use two. This isn't the end of the world for this particular flatish route, but will be an issue on future routes that would have more hills.

I don't really even need the shoe at the tip of the path, just thought it made the path a bit more interesting.

Do you think there may be any other tools that might work, or am I doing something wrong with the path tool?

Report · Nov 28, 2019

When you are working on projects that include a moving camera it is very important to establish a ground plane. It doesn't matter if it is a script that creates a camera for google earth, AE's camera tracker, or a third party camera tracking solution. When you get a solution for the camera you need to add some kind of reference solid so you can make sure you have properly positioned the surface.

If you have hills or valleys you will need to align other layers with those surfaces. Every layer you add will be flat. If you want a single layer to actually follow the contours (elevation changes) in a fly-over video you will need to purchase 3rd party solutions. I won't go into that right now but that kind of capability can get very expensive. The latest screenshots look like the path bent to follow the terrain. You can't do that very easily with AE's default toolset.

For a moving aerial view like the one you are working with, I find it easiest to add solids, then add Effects>Generate>Grid to the solid, then check the tracking to make sure that the grid is sticking to the ground.

Sticking to the flat layers idea, once you align the surfaces with the video and they stick you can start setting up your path very easily. Here's a step by step:

If you scaled your reference layer you need to reset the scale to 100%
Lock the reference layer (Important)
Create a new shape layer by drawing at least one point with the pen tool
Make the shape layer 3D
Hold down the Shift Key and parent the shape layer (your path) to the reference layer

Now the shape layer is aligned to the reference layer and you can draw your path directly on the map. You can either set the reference layer as a guide layer or turn it off. I usually do both.

All that is left is to edit the path by drawing directly on the map. This is easiest if you use the pen tool (g) and the Alt/Option, Ctrl/Cmnd keys as modifiers. You will end up with a path that sticks to your map. You can use Trim Paths to have the path draw on the map as the camera moves. The two latest screenshots show the path slightly above the surface. That is easy to do if you have Shift + parented the solid layer to the reference layer and locked the reference layer. All you have to do us adjust the Z position of the shape layer by clicking on the Z-axis (orientation set to layer space) and dragging a bit. This can cause misalignment if you move the layer too far above the surface.

If there are hills that or valleys that you want to follow you can align reference layers to those surfaces and follow the same steps to match up the path to the surfaces. It is actually pretty easy to create invisible joints in the lines if you remember to lock layers.

If I get some free time later today I'll post some screenshots from one of my typical aerial camera tracking projects.

There is one other option that is fairly inexpensive and can be very useful for some similar projects. It's a plug-in/script from AE Scripts called Lockdown. For some projects, this product may be very useful.

Report · Nov 28, 2019

Thanks so much for the detailed response Rick!

I mostly understand what you're talking about. The best will be for me to play around now I think. What I've done to account for the change in altitude, now that I understand that the path layer is basically a 2d object laying flat in a 3d space, is I added an expression that moves the whole path up and down with the changing terrain. It seems to be working quite well. I think with more mountanous terrain, the hack will be more noticable, but for the moment it's working. Here's a link to it with the changes. You can see the whole path move (and this is the worst where it happens) https://www.youtube.com/watch?v=hl6EDi_yMOY

I also dropped the shoe layer at the head of the path, because it's just complicating things

I'd love to see how you work with your aerial tracking projects. Please post some screenshots if you get the time.