Skip to 0 minutes and 7 seconds Tracking is basically anything that moves, the computer can probably tell you how that thing moves much better than you can try and approximate how that thing is moving. So that could be the camera moving. That can be something within the frame moving itself. And it can be– it’s the most useful tool for VFX because so much of what you’re trying to do is stick something on top of something else. And everything is always moving in shot. Whether it’s hand held or if it’s stilled like a static thing, you’re probably going to end up needing to use tracking for something.
Skip to 0 minutes and 48 seconds A music video we did called “Global Warming”– in that music video, there’s a lot of corner pinning, which is– there’s a photographer has been taking photos. And she’s developing the photos. And in the photos, we’ve got the guy singing. And so we’re corner pinning all that stuff. And so there’s a lot of tracking going on to be getting these photos who are getting stuck up on little pegs, getting them in place. A lot of the time, the advice is always put as many markers down as you can. Because you can paint those out really easily, especially because, well, you know, the computers are already gone, yeah, I’ve seen that point. So it’s definitely got that solid.
Skip to 1 minute and 25 seconds But a lot of the time, the problem that you’ve got is cameras these days, if you’re shooting something, you want it to look like the rest of the programme or the film or whatever it is you’re making. The focus is always going to be pretty shallow and tracking markers go out pretty quickly. So rather than necessarily being, you know, OK, I’ve drawn a cross on the background, as long as there is something sharp that’s got a corner, got an edge, and if that can remain sharp, then great.
Skip to 1 minute and 54 seconds And actually, a lot of the time, I suppose the really useful thing to do would be to shoot at a high frame rate, which is something that we need to encourage more, actually, for when you’re doing tracking shots, especially. The idea is get rid of the motion blur. So not necessarily even shoot at a high frame rate, but shoot at a high shutter speed so that you don’t have any motion blur so everything’s as sharp as it can be. And when you’re first using that shot, it’s going to look horrible. But then in post, you can add motion blur and it works really well.
Skip to 2 minutes and 30 seconds And After Effects does a really good job of creating motion and making it look more like the rest of the film.
The world according to the Blaine Brothers: tracking
In this video the Blaine Brothers talk about a particular job they did which used a different type of tracking to what you’ve seen so far in the HitFilm exercise.
In their music video for legendary reggae group Steel Pulse, the brothers used a type of tracking known as “corner pinning” to find the corners of photographs hanging from pegs and attach moving images of the band to them.
Watch the original video of Global Warning by Steel Pulse (2004). This video is over 10 years old now, so is representative of that time. It’s this same corner pinning method that is often used these days for replacing car number plates in commercials or films.
At around 1.58 in the video Chris Blaine mentions tracking can be aided by higher frame rates, or rather higher shutter speeds. This is a facility most digital cameras have. The more frames per second or faster shutter speeds for each frame means you can get crisper shots with less motion blur and therefore more accurate tracking because the edges of objects are clearer.
An optional note for HitFilm users:
If you want to try corner pinning, it can be achieved in HitFilm by using the Quad Warp effect.
The effect provides four positionable points which can warp the picture or object – for instance to fit a graphic to a billboard. These points can then be hand-animated or tracked.
Using the knowledge you’ve already gained this week and building on the first practical exercise, can you figure out how to use corner pinning in HitFilm 4 Express? Try filming a shot featuring a television screen or a billboard sign, then track the corners and use that data with the quad warp effect to put a new image or graphic in the sign or screen. Help each other out in the comments and we’ll be on hand to offer advice as well.
© Norwich University of the Arts (NUA)