Motion Tracking & Object Tracking inside Cinema 4D: The Motion Tracker Graph View

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Learn about one of the very helpful Interface elements we have in our Motion Tracking Arsenal

One of the very helpful Interface elements we have in our Motion Tracking Arsenal, is the "Motion Tracker Graph". This is a Dope Sheet of all trackers, automatic and manual, and can assist us with "cleaning up" our 2D solve, and manual tracking.



One of the very helpful interface elements, we have in our motion tracker. Arsenal is the motion tracker graph. Let's go and open it from the motion tracker menu, motion tracker graph view and here it is. Now mind you, you need to have a motion tracker object selected, and then you see this, but if you press H so to zoom in, you can see all of the information for all the automatic tracks, all these little buggers here for the duration of our animation. Okay. And what you see here, the way this is sorted is based on which part of our shot that tracker is visible. So you can go here in the beginning, and you will see that the particular tracker we're looking at over here is somewhere here in the back. Look at that, there you go. So as I scrub from zero, you can see it's nice and orange and then it loses it. There you go. So you can presume from this that this little tracker here, was only found during the automatic tracking process from frame zero up to frame 12 or 13 or something like that. Now, let's take a look at the colors for a moment. Let's bring this in view. You can see that we have all these different values of green. That the brighter the green, the lower the error threshold. And you will see that we don't have much error. And the reason is, if we go to our motion tracker, went to the to the 2D tracking automatic tracking and we have our error threshold. Now, if I turn off the error threshold, this will allow us to see all those automatic tracks that have a very high error variance as well. So this is what the color coding does and how it works in tandem with the filters. So let me turn this on. And let's take a look at the few of the other colors. The yellow is a key frame. So where you see yellow, that means that a snapshot of the pattern was taken at this frame for this particular tracker. Let's see if we can find this one now. Where is this tracker? First of all, I'm going to do the following. I am going to put this down here. And number two, I'm going to go to my footage and make sure we hit the full footage. There you go. So you can see this tracker up here. It's represented over here and has a snapshot of this. And if the tracker is happy, then I'm happy, I have no problem. You can see various amounts of error. But let's see what happens on either side. If we go to the end of it, you can see we have this fuchsia, this magenta color. And it says when I hover over it, error filter trim. This means that the values after this were trimmed because of our error threshold. That's simple as it is. I hover over this one, it's a smart acceleration filter trim and so forth. So this color code tells us the reason why there are no more calculated positions from this point onwards. It's either based on acceleration filter or based on the error filter and so forth. When there's nothing here, it just means that the tracker was lost. It wasn't filtered. It was that it couldn't find any more information on this frame. So let me do this. Let's see if we can find this little tracker and close this for a second. I hate when big things are right in my face. That's why I have two monitors but you can't do tutorials with two monitors. Full footage and if we look around for a few seconds, we may be able to find that outside tracker which is the one right over here. Okay, so it just vanished. There you go, it vanished. It went out of frame and that's why there was no color code to tell us why this particular tracker vanished. Excellent. So these are very helpful tools. They allow you to see what's going on and we will use it quite extensively when we do the manual tracking. Now, let's go and see what other modes we have here. I'm going to press H to zoom everything, and when the vertical resolution is one pixel, it doesn't get smaller anymore. So there are trackers both on the bottom and above, but it can't become smaller than one pixel. So you'll find that for scenes that have lots, and lots and lots of tracks you won't be able to see them all at the same time, unfortunately. Let's take a look at what's going to happen if I go to motion tracker, 2D tracking and change the error threshold. So I'm going to make it higher so we have fewer tracks. Sorry, that's more tracks. I'm going to put it very low. And you can see that we only see the tracks that have an error threshold value lower than 4%. Now the other trackers are not deleted. They're just hidden and they don't participate in the calculation of the camera solve. And that's fantastic because if we change our minds about something like the error threshold or smart acceleration or whatever, we can always go and just move the filter and we don't have to track again. Excellent. So this is a dope sheet, very helpful but we can go here where we have the actual graph mode. If I click on this, you will see the same things but as graphs. Interesting? You don't see a dope sheet anymore. You can see the actual graphs, and this is the error value for the specific tracker. And you can modify the error threshold by moving this red line here. So visually, you can use this. Let me press H and actually, what I'm going to do is dock it here. Press H so I have an overview of it. Then go to my footage, and go to full footage. So I can see what's going on here and I can say okay. This tracker goes from zero...from zero error because that's where the pattern was recorded. When the pattern gets recorded, the error is zero because that pattern defines what everything else is going to be compared to. And I can either select them here, or I can go and select them here. But we are on this frame, and you can see that this line which indicates the life time and the error of the particular tracker is not on frame G. So we have to move here in order to find it. And there it is. It's over here. And normally you will see the errors grow as the tracker evolves. That's why we add more and more and more trackers on new features so that the overall error threshold is quite low. Now the lower the error threshold, the fewer trackers we're going to have. So sometimes you may assume that we can make this extremely small. and we're going to have a perfect solve, but then you can have other problems. Like, for example, a lack of enough automatic trackers to average out any other errors. But overall, we can use the motion tracker graph view to fine tune our track and make our solve better. Finally to close this off. I would like to show you that we can see the actual 2D tracking speed or the 2D tracking acceleration. These are a couple of things that have to do with the other two filters. So again let me right click and undock this. Closing off this video, you have the ability to filter your trackers based on any of these three things. I personally work with the error and in my view for these kind of shots, 15% is good enough. And what that percent means, I'm not really sure, but it works quite well with 15%. And I mostly work in this view when I'm doing my manual tracking and we'll see this a bit later. We're going to be using the motion track graph view quite a lot.
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