Motion Tracking & Object Tracking inside Cinema 4D: Tracking an easy feature of the object

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Learn how to track an easy feature of an object.

In this video, we will track, a relatively easy feature of our shot. Please make sure to watch the previous video as well, as they complement each other, and will overall, give you a good idea of the manual tracking process.

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Transcript

In this video, we will continue our exploration on the tracking of 2D features for an object track. In this case, I'm going to choose a feature which doesn't have many problems. So it represents a best case scenario, as I call it. And in our footage, you can see we have our previous tracker already tracked, our previous feature to be precise. And I'm going to focus on this one here, so let me zoom in. What you will see, is that it never goes in front or behind another feature, and that will make the shape relatively constant throughout , and that's fantastic. So let's go right here in the middle, and what I'm going to do now is press Command and in left click to create a tracker, and make it slightly bigger, and let's make it flush, with a circumference, I'm going to zoom in, and use my Command, arrows or Control as in the PC. to nudge this into place. And I think this is a very good feature now. So what I'm going to do is, rip this to the side. At the same time I'm going to either go here, and select the graph view from here or just click on this, and I'm going to dock it over here, and I'm going to make it slightly smaller by pressing 2 on my keyboard, and zooming out. Fantastic. What I'm going to do now, is make sure the auto update tracks is on, and you can see that automatically it was bi-directionally tracked. So let's go and see how it looks. Now you can see that the tracker is moving. Although the lock view on tracks, seems to be activated. This is an interface glitch. Whenever you change a tracker, you have to click on it again to activate it. So now it's going to work. So we go forwards, and you can see that only at this point it kind of jumps away, and that is probably because some sort of change of contrast. But anyway, I'm going to go to the last key frame I consider good enough. This one for example, maybe a few more. There you go. And although it seems to have moved ever so slightly, I think it's good enough for what we want to do. So go here, right click, and say insert key at track position, and because the auto update tracks is active you will see that it will track a bit more by itself. And then go here, right click insert key at track position. You can watch the progress of the tracking over here. I'm going to move forward, and you can see that we have a bit of a problem over here. So what I'm going to do is do a bit of manual tracking on this end, and I'm going to move this over here, and you will see that it didn't track backwards although it should be bi-directional. And that is because the front tracking from this key frame takes precedent. So, unfortunately, you will see that we get a significant jump. So I'm going to divide, and conquer. I'm going to go somewhere here, and move this right to the center, and some sort of calculation is going to occur over there, and then go right here in the middle, move this, and it will auto track. So I've conquered these ones. Then I'm going to go right here in the middle, and do this one here. Excellent. And then I think I'm just going to manually correct this. So again by using my one frame forwards, one frame backwards, my G, and F keys on the keyboard, I'm going to make sure that the tracker is nicely placed. You can see we have a huge jump over here, so Command and nudge to the right. You can see takes a bit of time, because every time it's processing a few frames. Luckily they're not many. So it takes a split second. So let's go and move this. There you go. And again, let's move this to the right, and let's do this, and a bit more. That seems a bit better. And actually I can do it with my mouse. A bit more. Maybe I should go in the middle here, and bring this over here, and then over here. You can see there's a jump. I'm going to move it this way, and here a bit more. There's a bit of a jump. That's not too bad. Excellent. If you want to be a bit more precise you can always go, and correct these. You can see there's a slight error value here. So we can divide, and conquer here as well, and so forth. So you know you can do it or not. At the end, if you have trackers of this quality, but quite a few of them, the actual error will average out, so you won't have such a problem. So let me move backwards now, see what happens here. There you go, we lose it at this point. Let's go over here, and set a key at track position. You can see that it slips ever so slightly at this position over here. We see this jump. I'm going to make sure that this is slightly but assented. There you go. Very minor jump, but that's good enough. And let's see what happens in the previous frames. Not bad, very minor little glitch here because we get the other feature jumping in. So I can use my nudge on my keyboard. I'm going to set a key and track position over here, and let's see... Good. That sort of corrected it, and all the way back here. Excellent. So let's pull out. Let's rewind, and press play, and you will see that overall, it might not be 100% accurate, but it's stable enough, and it's going to contribute quite well in our solution. Oh, I just saw a jump. There you go. That's a big jump. That is something I do not like. So I think this is a good enough frame to go and correct this. And let's move here, and try and create some sort of manual tracking for this region. So we're here...there you go, that's where the jump begins. So I can do my manual tweaking, and there you go. A bit more of a jump. You can see that happens when the background changes significantly. And I'm going backwards and forwards. One frame backwards and one frame forwards. And you can see there's one more jump we need to take care of here. There you go, just to create a more smooth transition. And I think that now this is good enough. Let's see, not bad, not bad. Nice, nice, and smooth. Good. A bit of slipping, but that's going to be taken care of by the average of the errors. So this is what it takes, approximately five minutes, maybe less. And if you want to add a few minutes, just to create a few more manual tracks to refine this, and this represents a fairly easy track. Now one thing before I close off this video, there's a very important thing that has to do with the colorization. So we've been tracking white trackers on dark backgrounds. Our motion tracker uses the luminance value. The problem with that is that certain pure colors like green, and red, when they're over grayish areas, the contrast is not that good. So although this green color seems to be just jumping out compared to the very dull gray background, this won't be a very easy tracker to track because the contrast of the luminance of the green color, and the luminance of the background are quite similar. Let's see this frame in Photoshop, so I show you exactly what I mean. So here's the first frame, and let's zoom in here, and let me change this to a grayscale image. And you can see that there's not a lot of contrast if you compare these two, and these two. Especially this one, I think this was the red one. Yes, the red one in particular, because the background is reddish-gray. And let me go back to my grayscale, you can see that here, the contrast is not that good. So, when you're shooting your scene, make sure that there's a good luminance contrast between your features, and any background. Or there's another method you can use. You can take your footage, and you can process it through Photoshop, or After Effects, or Premier, or any other program that you can do some color corrections to a sequence of images or a movie, and make sure that you achieve the maximum contrast you can. And that will give you a very good solve, despite the fact that it's on a black and white image. Those are some of the techniques that you may use. But it's good to know, if sometimes you're wondering why a certain feature cannot be followed precisely by the auto-tracking process, that is the reason, because our tracker currently only uses the luminance values.
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