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The MoGraph Tracer object generates spline information based on the position of objects in the scene. It can also generate those splines based on the points that make up those objects. This can be incredibly useful for modeling and for rigging and for all kinds of situations. I'm going to show you how to make a very quick abstract background using the Tracer object to give you a feel for what it can do. So I've got a basic scene here. I'm going to hit Play to show you what's going on. And you can see my objects are just kind of randomly rotating through the scene. What I want to do is to create spline information based on the positions of each of these cubes, linking them together.
So if I go to the MoGraph menu and add a Tracer object to the scene, the Tracer object, under its Object Properties, has this field, the Trace Link field. The Tracer object doesn't do anything until this Trace Link field is filled. A very important thing to remember about the Tracer is that it needs to be below any objects that are being used in the Trace Link field. It needs to be below them in the Object Manager. So let's take the Tracer and drag it down to the very bottom. Now let's take the Cloner object and drag it into the Trace Link field. And when we do that, it looks like nothing happened.
That's because we're telling it to trace paths. If we were to hit Play, you'll see that little splines are being drawn based on the position of each of those cubes. If I were to go to the Time Effector and adjust the speed of those objects by having them move faster, let's rewind back to 0 and hit Play again, you'll see that I get very long splines. And that is incredibly fun to watch, but if I hit Cmd+R on the keyboard, you'll see that nothing really happens with the Tracer object.
That's because the Tracer object is generating splines, and the splines don't render. So in order to have something actually visible in the scene, we need to use that Tracer in one of the spline-based NURBS objects. In this case, we're going to use it inside of the Sweep NURBS. So let's add a Sweep NURBS to the scene. Oops, I accidentally added a Hyper NURBS. Let's delete that and add in a Sweep NURBS. So let's click and hold on the Hyper NURBS and add a Sweep NURB, and drag the Sweep NURBS down just above the Tracer object. Now drag the Tracer object into the Sweep NURBS.
Now initially, nothing happens, that's because we have to tell the Sweep NURBS what to trace along that Tracer object. And so, let's go to the Spline objects and let's add in a Circle Spline. The Circle Spline is very large right now so let's make it small. Hit T on the keyboard and scale it way down. That's pretty good size right there. I want to make it much smaller than the cubes. Now let's take the circle and drag it into the Sweep NURBS, and the way the hierarchy works is it says, "Take this circle and sweep it along this Tracer object." And so what you end up with is paths based on the position information of each of these cubes.
Now the awesome thing is that you can go into the Sweep NURBS and adjust the shapes of these. Now they're kind of chunky and I want to have them taper off as if each of the cubes was its own little comet. So I'll go into the Sweep NURBS and under the Details, let's twirl that open and raise it up, there is a Scale and Rotation. We want to adjust the Scale. And anytime you see a field like this, it's start and end. And I want to have the start, which is going to be this end or this end of the object, go smaller, so let's drag that down. I'll drag those down in time like that.
And you'll see that now I have these little points, so if we rewind back to zero. Now one of the weird things about the Tracer object is that there's always a little bit of lag and sometimes you need to force the screen. I just hit the letter A on the keyboard to force the screen to redraw. And now I'm going to hit Play. And the screen is very chunky, but you can get a feel for what it's doing by making those tracers. And you can see it reverts to Box Mode. So we need to do a preview movie. When I stop the playback, you can see I'm getting these great lines in the scene.
Let's make our cubes go even farther by adjusting The Time Effector. And so, I had it set for 244. Let's make it something really extreme like, say, 5,000. And then rewind back to 0. And I'll hit A on the keyboard to redraw the frame. And now, rather than trying to hit Play here, let's make a preview movie. Let's go Opt+B or Alt+B, and then don't forget to change the Preview movie from Full Render to Software Preview. And then I'm going to go to Image Size and adjust the size and call it 640.
And that's the horizontal resolution, it's going to keep the aspect ratio that's set in the Render Settings. And the Render Settings are just the defaults right now, so they're square. So I'll hit OK here, and it's going to go through and think about it. Once the preview movie is done, it's going to pop up the picture viewer here. So let's hit Play. The first time through, it's going to try and cache those frames, and each time it goes through, there we go. So now, you can see we're getting this really cool movement based on the position of those splines. And so, if we close up the picture viewer, and let's hit Play on the keyboard and let it chunk through for a minute, somewhere around frame 30 or so, so we can get a feel for how long those splines are.
And one of the cool things you can do is add a Camera to this. Let's go and add a Camera object to the scene, and I'm going to look through that camera. And let's go to the Render Settings and activate Depth of Field. Now before I do that, let's adjust the Depth Settings on the camera. So let's go to the Object Properties and check our Focus Distance. And the Focus Distance defaults to 2,000 meters. And let's see where that is relative to our objects. Let's click on the middle mouse button and get our four-way view going. You can see we're fairly well deep inside this area, and let's back out a bit so that we're going to be a little bit over here and over here so we're in a more dense part of the cloud when we look through the camera.
We can back out here and see the same thing. And then what we'll do is in the Camera Properties, we'll go to the Details section and let's activate Rear Blur. And that's going to give us this cloud here. I'll leave the Front Blur alone. We should have a little bit of Depth of Field going on. Let's go to the Render Settings, Cmd+B or Ctrl+B, and activate the standard Depth of Field. We go to Effects, and then Depth of Field, and now we can turn that closed. And when I look through the camera now, let's do a quick rendering. Let's bring that full screen and do a Cmd+R or Ctrl+R on the keyboard.
And it's a post effect and so after the post effect happens, you see that we get this really cool-looking Depth of Field. Now this Depth of Field effect is not nearly as nice as the Physical Render Depth of Field, but it renders very fast. And you can see it gives us a really cool abstract result. The Tracer object has literally a million uses. It can connect things with splines, it can draw splines based on the position and point information as objects move through the scene. You can have all kinds of fun with it. Even though it's not just for abstracts, you can have a lot of fun creating this type of animation with the Tracer object.
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