Motion Tracker - Editing Constraints

[PSCGI]

Hi. I've started learning motion tracking in Cinema 4D and tracking in general, I'm currently following a tutorial from Youtube and unfortunately my scene doesn't seem to be aligned good enough with the footage (after doing tracking, I started adding some planes but the perspective is a bit off so eg. my plane's lines do not match the lines of the fence in the footage) but unfortunately I have no idea how to get access to my vector/planar constraint points again in order to change their positions and thus realign everything. No matter if I double click on the constraints, if I'm in a Model or 2D Tracker mode, no matter if I have a Motion Tracker object selected or not, I just cannot reach those points. It basically looks like this:

When I'm in a 2D Tracker mode (not Model or Object etc.) and I do have Motion Tracker object selected, I do have tracks visible and Auto Features are behind the footage.
In the same setup but if I click on an empty field in the Object Manager my tracks disappear but all Auto Features become visible in front of the footage.
If I'm in a 2D Tracker mode and I do have Motion Tracker object selected and then I also click on any of my constraints, then all tracks disappear again.

Could anyone help me please how to reach those constraint points? I'll be very thankful.

[Dr. Sassi]

Hi PSCGI

I have very little to go on; a video on YouTube that can be horrible or excellent, I don't know. I get that it gets you into a problem.

The Motion Tracker Object must be active, the scene needs to be entirely 3D Solved, and the Tag that needs to be adjusted must be selected.

What I can do is track some footage and show you the interface. Anything else would be wild guesswork, which I don't do here.
Here is a tracking screen record with Cinema 4D, 2024.5; I do not rely on memory or what worked a while ago; I do it consistently from scratch.
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2024_Clips_DRS/20240722_Tracking.mp4

If you have the footage and the lens grid as a Dropbox file (or Google, Adobe, Apple, or Wetransfer file, I'm happy to look into it. Other cloud services or shortened URLs I do not consider safe.)

I typically would link a Cineversity series here, but currently, they are moving to a new server. Sorry about that

Besides, most of the time, something is not working; it comes down to a few things.

No Lens grid was shot
Too little parallax
Too much motion blur
Minimal features
Mostly far away features are used
Lock off camera
False features were not deleted
Reflective surfaces are not excluded
Rolling shutter in the footage
Some big things are moving in the footage, such as water, clouds, etc.
Heat waves
Zooming
… and indeed, I can go on for a while.

If you have all that under control, the motion-tracking Object is active, and the tab you chose is not the problem.

Delete the Tags and call up new ones; if the 3D solve was OK, you can set this up anytime again.

All the best

[PSCGI]

Hi Dr. Sassi,

Thank you for your answer. I'm trying to learn from the best like of course Maxon Training Team, Motion Design School, Coloso etc. but yea sometimes certain things do not work as in the videos and then all sorts of problems begin.

So regarding that lack of access to the constrains - looks like most of the time it does work and I am able to adjust it, just sometimes it doesn't, I'm gonna keep looking at it and try to figure out what's wrong when it doesn't work.

And regarding the tracking itself (and the purpose why I did want to adjust the constraints) - so here are the problems I encounter:

1. Regarding the position constraint: so let's say I pick a certain feature and the grid looks pretty much ok, but then I decide to change a feature to a neighbouring one (and all those features that I’m choosing from are eg. on the street, not one on the street and another one in a completely different place like on a wall or something) and suddenly the grid goes crazy. All the features that I’m choosing from are green and they seem to be placed nicely on the street. What may be the reason for that? (video number 1).
2. Planar constraints: same here, I choose 3 or 4 features on the street and sometimes it works nicely and sometimes the grid is completely skewed despite choosing features on the same plane like street. Also sometimes selecting (or rather snapping to) features works fine, sometimes it doesn’t snap (video number 2).
3. Vector constraints: even though I select features that lay eg. on the fence , the perspective can be totally off.
4. Does it matter whether I create position/planar/vector constraints first?

---

5. Regarding the lens grid - so far I've used videos from the Internet but I don't remember anyone using it in those tutorials/courses (from Maxon Training Team, Coloso etc.) that I've seen so I guess that's not necessary?
6. Is it worth to create 2D tracks in a few different sections of a video? Like in the most important part, at the beginning etc.? And do they somehow blend together?
7. Could I actually skip auto tracks and create all tracks manually?
8. I think Noseman said in one of Maxon Training Team Youtube videos that 7 good tracks is all I need to succesfully track a footage so could I just create 7 manual tracks in nice constrasty spots and have a nice track?
9. On the other hand in a course that I'm doing now a guy (that has worked for top studios in the world, not just a random youtuber) added like 10000 auto-tracks so that's quite a difference, 7 vs 10000. But actually he generated a mesh after that so I assume that I do need that much tracks to generate dense, accurate mesh? But other than that, if I don't want to generate a mesh does it make sense to create so many tracks?
10. If I have a veeery very long footage that I want to track with lots of diffucult areas like reflections, trees etc., do I just have to manually remove all bad tracks no matter how much time it takes? Cause all those bad tracks, (if I keep them, and no matter how many good, green tracks I have) make the final tracking result worse/bad/impossible to use, is that correct?

I've also created some screenshots, here's a link to WeTransfer: https://we.tl/t-klxiuNV3Bs
7. There's a folder called NarrowStreet that I wanted to use to follow a nice course that I'm currently doing and each time I tried to track it in Cinema, I ended up having a grid that was skewed. In the end I purchased a monthly license of PFTrack and I succesfully tracked it there after doing like 1 or 2 tutorials so I have no idea whether I was doing something wrong in Cinema or maybe is this footage somehow too difficult for Cinema to track? There's the entire video in the Videos_Pexel.com folder.
8. There'a a Street folder with a street that I wanted to track but again each time the perspective was off. I also showed there how different it can look after simply changing the position constraint (the problem that I mentioned in my 1st question)
9. Folder Recordings shows what happens when I change either position constraints (again question number 1) ar planar constraints (question number 2), it also shows that something it doesn't snap to the features.
10. And folder Videos_Pexel.com containts 3 videos from Pexels.com and my question is - are there difficult to track? Maybe so far I've just tried to track videos that aren't easy?

Wow my answer turned into quite a long post so sorry for that but hopefully it's not that bad with all those numbers that I added and once again I'd be super thanful for your help

[Dr. Sassi]

Hi PSCGI,

Thanks for the files.

Here are three trackings back; the footage is not included.
https://stcineversityprod02.blob.core.windows.net/$web/Cineversity_Forum_Support/2024_PROJECTS_DRS/20240806_CV4_2024_drs_24_TR01-03.zip

First, without a lens grid, there is no precise tracking, except your lens has no distortion. Which is rather rare, as there is always something. Shooting a grid close and filming at a greater distance makes no sense; if the lens "Breathes" and the distortion changes, the points move differently and faster in different places. Sometimes, that is not a given, especially with Drones (shot three)

If there is no set survey, then you have even more guesses. A set survey is a measurement of things, preferably XYZ-oriented.

Your footage did not show an obvious rolling shutter.

I had no measured focus length 9What is printed on a lens is an orientation, except it was measured, and the lens (again) is not breathing. Zoom lenses are an even more difficult theme.

Far-away tracker markers are often useless. Tracker markers with leaves and wind are useless and sometimes kill the precision.

Light change bases, reflection, and other trackers using moving things must all be deleted.

Manual tracking means frame by frame. Each! With 1500+ frames in one clip along, good luck with that test of your patience.

Is seven enough if the footage is 100%, the lens has no distortion or is measured, there is no Motion blur, and the seven are starting to finish stable, perhaps? Please don't count on such perfect situations. I have tracked since the late '90s and have not gotten a shot in that quality. (Match Mover, BouJou, Syntheyes, and others like the one in After Effects and Nuke or Fusion are the others that I use occasionally. None of them have ever given me a one-click and ready-to-use result.

The mesh thingy is an idea you can find, for example, in Syntheyes, for at least over a decade. It assumes that a cluster of tracking points occupy the same object, with a solid shape, similar to the Coalesce tracker to a cloud, Which is used, for example, in Mocha (Planar Tracker) or DaVinci (Some might argue with me here to simplify, and I would agree.

The switch between 2D Tracks might bring back the visuals on screen.

It would help if you inspected the Graph Editor of the Motion Tracker.

I did not find them difficult to track, even though I had zero data applied to it, which is normally a big no to start. Setting survey and camera data is a must.

Reflections (and again (trees) need masks or cleaned up later. I would trust the algorithm to see it. Ocean and moving clouds, the same idea, can destroy the solution.

Tracking features that are tangential to the camera are less preferable. There are many more scenarios, but that is often specific to a shot. I would not finish this post even if I tried to share it.

The tracker tries to find where the tracking features are; the solution freezes them in space. Any Vector, Position, or Planar allows to rotate, scale, and position it; that feature cloud keeps the relation.

Once the cloud is defined, each Null sits where the tracker was; while the best tracker defines the cloud position, many are not where they were in reality; there is a tolerance.

You are using different trackers for the planar and getting different results that are easy to understand if you look at the side view of the feature cloud.

Tim Dobbert has written a book about it, and I can't repeat all of that; from my point of view, that is a must-read.

My best wishes