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I'm not really following your workflow. Maybe there is a little misunderstanding of how the Camera Tracker works.
The only keyframes that are added when you use the Track Camera feature are for the camera. If you do not set an origin and ground plane before you start adding the camera and the nulls or placeholder solids the camera could be pointed anywhere in AE's 3D world so the coordinates do not match up with another composition. When you set an origin and ground plane, at that point in time, If you add a reference solid and a camera the solid will be at 0,0,0 and if the plane you select is horizontal, the orientation will be 270º, 0º, 0º. The camera could be anywhere and the camera's orientation could be anywhere. This means that none of the data from the camera tracker is usable in another composition with another shot.
If you do not set an origin and ground plane and put a reference solid there it's awfully difficult to line things up in the rest of the shot if you are not lucky enough to have at least 3 trackers fall where you want to place things.
Now on to your problem. Let's just talk about one ink drop. Some part of the ink drop should stick to the surface and some other part should run downhill or spread out. I take it that you want to animate one ink drop and then duplicate it so that it falls on other parts of the table. The easiest way to do that is to position a reference solid using the camera tracker's points or set a grid on the solid placed on the origin and ground plane and use that for reference. When you get the second solid, easier to use than nulls because you can actually see if they are sticking to the surface, then you could simply duplicate your first animated ink drop, then hold down the shift key and parent it to the reference solid and it would move to that location. If the reference solid sticks to the surface properly, the animated ink drop will do the same. You can then turn off the reference solid, my preferred method because sometimes I need to go back and make adjustments or delete it if you are sure you are done with it.
That's how I would approach the problem you are describing. Without a reference solid at the origin and ground plane and other reference solids in the scene, it's almost impossible to move things into the right place. My reference solid at the origin and ground plane almost always has a grid applied and it's big enough to cover most of the surface. I keep it there until the composite has been checked for accuracy and all of the motion is perfect. For example, here's a shot set up to add objects to the arena. The grid is on the reference solid at 0,0,0. This gives me a really good way to check the accuracy of the camera solution and an easy reference for placing other objects in AE's 3D world:
After everything is inserted I'll just turn off the layer. By the way. It took seven tries to get the origin and ground plane in the right spot so the grid stuck perfectly to the arena floor. Only one camera solve with detailed analysis turned on, but seven tries to find the right combination of trackers to define the surface.
Without seeing your comp it's pretty hard to give you any better advice.
Thank you so much for the detailed advice! This is really helpful! I think maybe I didn't do a very good job of explaining how I set everything up. My apologies for that. My process was like this:
1) Start with footage of table
2) Use 3D Tracker Camera to provide points in 3D space on the table
3) Create a null/solid object on one of the track points on the table
4) Bring some stock ink drop footage into the comp - e.g. https://www.videezy.com/abstract/5487-ink-drops-stock-video-2
4.5) Key out the paper leaving only the ink (not really relevant to this post)
5) Make the ink layer 3D and parent it to the reference null
6) Position to taste on the table.
1) Make a new comp called Ink Drop 22) Copy/paste everything from Ink Drop 1 into Ink Drop 2
3) Hide the table footage later (it probably doesn't need to be copied in the first place, but I wasn't sure if the 3D Camera Tracker layer needed the original footage layer in the same comp to work properly)
4) Lock the table footage, camera tracker, and null object layers leaving only the ink layer(s) unlocked
5) Ctrl A to select all the ink layers
6) Drag to desired new location.
The reason this doesn't work with the Ink Spread comps is because I've had to take additional steps to animate position change adjustments in the Ink Spread footage to get it to behave like I want. For example, take this clip. https://www.videezy.com/ink-drops-and-splatters/12453-ink-drop-expanding-in-wet-white-back ground-with-circle-shape-in-4k The way it is shot, a lot of the spreading gets cut off because it goes out of camera frame. That's bad for me because I want the ink drop to spread in a circular shape from the moment it hits the table. Since the ink in that footage BASICALLY makes a half circle as it spreads, I solved this problem by dropping in another instance of that footage, flipping one of the axes 180 degrees (z axis, in this case), and lining it up with its twin brother. This gives me roughly a circle of spreading ink.
Sort of! The spread wasn't happening at the speed I wanted. I needed it to react to the fact that multiple drops are added to the original pool as time goes on. So, I just keyframed in Scale adjustments at the right places. Problem solved, except the increased scale of each clip ended up squidging the two clips closer together deforming the circle shape they were previously in. No problem. I just keyframed Position adjustments in certain places to keep the two half-circles in the proper arrangement as they grew. Done.
Voi-- Yeah, almost.
That works wonderfully. It looks exactly like I want. However, when I go to the DUPLICATE step mentioned above - but this time on the Spread comp - I end up not being able to easily move my it. I could move the Ink Drop comp because there was no keyframing necessary to make the Drop footage look right. So, I could just Ctrl A on all the Ink layers and drag to my heart's content (which changes Position values on those layers) But, for the Spread comp, Position keyframes are necessary to assist the visual effect in the first place; I've already "used up" my ability to modify location with that value. If I Ctrl A all my Spread layers and try to move them by click/dragging them to a new location, I just create a new set of Position keyframes. Starting on the very next frame, I get to watch the Spread effect begin eerily floating across the table back to its original position.
Not exactly what I'm going for.
What I've done thus far is delete all the Position keyframes on the Spread layers, then drag them to where I want them to be (with the playhead on the first Position keyframe setting a new value), then re-do all the subsequent Position keyframes based on the new location. That's REALLY time-consuming.
Imagine a situation in Premiere Pro where you may have 5 video tracks sitting on top of each other that create some kind of crazy effect together. Say you're watching that part of your edit and you say, "EEEEEEEHHHHH. REALLY that's just a LITTLE too green." You could go through every layer's green channel and bring it down X percent until the whole image suits your liking, but a better thing to do would be to create an adjustment layer that sits atop them all and says, "Okay, guys. Do exactly what you're doing...but X% less." That's pretty much what I'm looking for. I really just need a way to tell all these layers to do exactly what they're already doing...but, like, 300 pixels OVER THERE (in 3D space with all the appropriate behind-the-scenes scale calculations that go with that akin to what you get with in the Transform effect).
Well, due to some freak accident last night, I lost my entire After Effects project. I still have the footage, but 3 weeks worth of vfx work has vanished.I have to start completely from scratch.
So, now more than ever, the need to move those Ink Spread comps without having to redo all the Position keyframe animations is imperative.
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Sorry to hear about that. I use a Raid 0+1 redundant array for all my critical data and all AEP files are stored in a Dropbox folder. Dropbox automatically saves deleted files for a while so they can be recovered and a Raid 0 + 1 array will still have your data if two of the three drives required completely fail at the same time. Numbered versions are also saved all the time. For most projects this is automatic. You've just learned a very expensive lesson.
As long as the perspective of your animated ink drop comps works in 2D, when you attach the nested comps in the Camera Tracked shot and the reference origin and ground plane and reference solids are perfectly attached to the surface Shift + parent will line up the ink spread comps perfectly. All you should have to do is rotate them on their vertical axis to fine tune the adjustments. After animating the ink spread comps and have camera tracked the shot it should only take a few minutes to place the ink spread comps in the scene.
If you have ink drops falling to the surface as footage you can also line them up with the reference solids using the Shift + parent trick, then rotate them upright and set them to orient to the camera. If the video of the ink drops are properly prepared that should also go very quickly.
So just to review for others following this thread, if my project involved a camera moving across a desk and ink was supposed to fall from above and spill on the desk I would:
- Film ink drops falling vertically with the camera sufficiently far away to let the ink reach the desktop but close enough to be large enough in the frame to be seen in the final composite against a background that could be easily removed or, depending on the shot of the desk, film them with a stationary camera from approximately the same angle and distance from the desk where the actual camera used to film the desk would be
- Film the desk making sure there was enough detail or fixed geometry in the shot to get an accurate camera track
- Animate or film ink spreading against a background I could easily remove from directly above
- Prepare the ink falling and the ink spreading shots in separate comps sized to fit the content
- Trim the shot of the desk and perform camera tracking probably with advanced analysis enabled
- Set an origin and ground plane, add a solid and a camera, edit the solid size so that it was big enough to cover the critical areas of the desktop, then add grid and check the camera track for accuracy
- Add as many reference solids as I could using the camera tracker making sure their position was exactly where I wanted it to be
- Add additional reference solids using the origin and ground plane solid with the grid as a guide
- Add the nested ink drop and ink spread comps to the project and adjust the anchor point to the center of the ink spread motion or the point where the ink drop stream is supposed to contact the desk
- Set all nested comps to 3D and then shift + parent them to the reference solids
- Adjust the orientation and scale of the nested ink comps
- Turn off or delete the reference solids, make final color and edge adjustments and render
That would get you to a shot where ink falls on a desk and spreads out with the least amount of work.
Thank you once more for the detailed walkthrough! There is definitely some stuff here that I'll have to look more into, but I'm confident I can figure it out with the details you've provided. Thanks so much!
Regarding the data loss, definitely good advice. However, this incident wasn't from a drive failure. I have most of my stuff on a 4 HDD RAID 10 array. I think when I deleted some unnecessary project files, I accidentally deleted my primary project file and the associated folders. I can't figure out why they didn't end up in my Recycle Bin, though. All folders together would have been < 50MB thus should have easily wound up in the bin rather than outright deleted. I don't really get it, but that's a topic for another thread.
Thanks again for the help!