Join Steve Wright for an in-depth discussion in this video Drawing X-splines, part of mocha 2.6 Essential Training.
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Here we'll take a look at drawing rotos using the X-Spline, one of the two spline types available in mocha. We'll learn about the Planar Tracker in lesson two, but for now we'll start by understanding how to roto in mocha manually. First, we'll need to load a clip. You can come up to the File menu and say New Project or you can use little icon here. It gets you the same thing. You get the New Project browser. We'll be looking at how to set up this New Project page later. Right now all we have to do is choose the pathname to where we want to go.
So wherever you have your Exercise Files, go to the Lesson_01_Media and select the Laptop. All you have to do is click on any one frame in the clip and click Open. We're all set. So now we can click OK. We'll need a little bit of screen navigation here so let's take a look at a couple of tools. Right up here, this little hand, that's the Pan and the magnifying glass, of course, is the Zoom. We also have quick keys, of course, which you're going to want to use really.
Hold down the X key to pan; hold down the Z key, click-and- drag vertically to zoom in and out. Also, there is the Asterisk (*) key which zooms the picture to fill the window and the Forward Slash (/) key which zooms the viewer down to 1:1. So let's draw in an X-Spline. Here is the X-Spline here, the B-Spline there. We will be taking a look at that guy in just a bit. We'll click on the X-Spline tool and just click, click, click here, there, over here, and then right-mouse button to close.
If you go to any tension handle you can do a right-mouse click and adjust the tension of all them at the same time. However, if you go to just one of them, click-and-drag on that one with the left-mouse button, then you can adjust the tension of just that one. And of course, if you have several of them selected, Cmd+Click to select another one. The left-mouse button will now adjust those two. So left-mouse button adjusts the tension of all the selected points. Right-mouse button adjusts the tension of all the points.
We'll put that back to a sharp edge so we can play with each point individually. You notice we have these zoom windows over here. They're designed to give you close-up view of whichever control point you're on and you can turn the zoom window on and off right here. We'll turn that one off for now. Another tool for helping you see your splines is the viewer brightness right here. If you click on this you can then draw a little circle around with your left-mouse cursor and darken it down or brighten it up, make it easier to see parts of the picture.
When you click away it remembers that number. Click back on the icon and it restores the viewer to the default gamma, click it a second time it goes back to yours. So we'll put that back to default. So let's adjust the control points. I am going to use the Z key to zoom in, click-and-drag, X key to pan. We'll adjust this point here and I'll get in real tight and adjust the tension of that point so I have a nice rounded corner. Most objects don't have sharp corners so you are invariably going to put a round corner in almost everything.
Pan over here and take a look at this one. Now this actually has two corners. So I need to insert another control point. To do that I come up here and I select the Insert tool. Notice the cursor changes to that little plus (+). So I can click-and-drag. I'm going to insert a point. I move off, I get the selection cursor. If I click-and-drag over here I'll get another point. To delete a point just select the point and hit the Delete key. Now I can adjust the tension of these two corners individually. I'll zoom in a little closer with Z and I'll relax the tension on that corner.
Now this isn't doing what I want. See, it has a nice sharp bend here, but then it has this gradual slope over there. That's because the next control point way over here is so far away the tension is not the same as this point over here. So we can fix that by using the Insert control point tool to add a second control point approximately the same distance away as this one. Watch this; I click on here and now the tension adjustment is symmetrical, because this locks it and that locks it.
We'll have the same problem right here. I try to round this corner and you see I'm getting this big slope. So I'm going to do same thing here. I'm going to insert a control point. So when I lay my cursor on the spline I get that little insertion logo. So I'll click-and-drag and put a new point right about there. I'll adjust this guy in and I can now adjust his tension and you see the curvature is now uniform between these two control points here. Let me adjust that up a little bit. Alright, let's go and look at some of other corners.
I am going to hit the Asterisk (*) key to zoom out and the Z key to zoom in down here to see what we got. X to pan. We'll slide this point right up here and I'll adjust the tension and get a nice rounded corner there that matches the case. That looks good. We'll pan over here. I'll select these two points and position them over here. Let's zoom in on this guy and see what we got going.
Once again we need to pull little radius on here, no sharp corners. So what I'll need is another control point here that's approximately the same distance away as this one, because once again watch what happens when I adjust the tension. You see, the slope is not even. So I'll insert a point, there is my insertion cursor, click here and now I get a nice uniform rounded corner. Again, I'm going to have the same issue here, because this control point is way down there.
So again I'll click and position a control point approximately the same distance away as that one, and now I can adjust the tension here for a nice rounded corner and everything looks very nice. Now the last point we have is over here. Now this is one place where you'll have a nice sharp point, because this is actually the intersection between two planes. So I am going to turn on my darker cursor so I can see this is the vase, that's the edge of my monitor, but when you get zoomed in this tight it's kind of hard to see.
Of course, this also has some motion blur and maybe some depth of field issues. So I'll hit the Asterisk (*) key now to zoom out to fill the frame. I'll click off to the side to deselect and now I can see my spline in purple outline. Like most clips this one has a lot of soft edges. To deal with that, mocha provides two splines, an inner and an outer. The tools for editing them are up here. The B tool which is selected by default; we select a point down here and we'll zoom in to see how that works.
The B tool, of course, is to move both points. We picked that up and both points are moved together. If we select the I tool, that's the inner, and that pulls in the inner splines. So in here it's solid, out here it's clear, and this is a transition zone, a soft edge. The E tool moves just and only the edge point. The A tool will move either point, depending on which one you're clicking on. Again we go back to the B tool and it'll move both points at the same time.
When we deselect the spline it only shows the one spline which is the inner edge. This helps eliminate screen clutter. Now I'll rehome the viewer with Asterisk (*) key.
- Understanding mocha preferences
- Drawing and editing splines
- Creating grids for tracking awkward surfaces
- Keyframing techniques for advanced rotoscoping
- Making stereo 3D conversions
- Stabilizing techniques for advanced tracking