Subtitles of the Movie

Now we're going to talk about Motion Blur. Motion blur is a phenomenon that occurs in regular film cameras, but where we see an object traveling at high speeds; it usually has a soft edge or a blurred edge at the front and back of the movement of the object. And this is caused by the way that a film camera works, there's a shutter that's spinning around and blocking the aperture and part of the image is exposed when that aperture is at the front, and then at the end of this travel or its shutter angle swinging around in front of the film. So obviously in Maya we don't have anything of the sort, it's purely a simulation of this sort of thing. So we have to come up with ways to fake this. And the way that it's generally done is the object that's moving at a high speed is sampled, if I'm going to for example render this frame eight, the renderer will take a look and see where it's going to be at a frame after that, and a frame before that, and use an average of those positions on the leading and trailing edges in order to give us that blur. So in this case, let's take a look at the render settings. You can go up to the Window rendering editor render settings. I'll move this over here. And inside of the Maya software renderer I'm going to set this to its defaults. Let's go to production quality, and that's set a bunch of defaults. And take a look at a render. So this is without any kind of motion blur, even though that object is moving at a high speed you can't really tell. So let me save that image, and minimize the render view. Now back here I'm going to head to the render settings, and there's a section here called motion blur. You can simply turn this on, and we'll leave these other defaults, the 3D motion blur will give us much better results than the 2D motion blur, particularly when there's any rotation involved with an object. OK so I'll take a look now at a render with motion blur, and you'll see this take quite a bit longer to render as it determines what each of these pixels looks like in a following and preceding frame, or a sub frame, and averages those. You can see we also get some transparency there in that blurred section, so we can still see that checkered or gridded background behind there. So that's much better, now we have that look of speed coming on that object because of the motion blur being enabled. Ok so you can see the before and after here, with and without that blur. For people coming from 2D animation or illustration, they're often used to drawing motion lines, which would usually follow the object, and I've taught people who were certain when they saw motion blur that it was doing it wrong because the front edge shouldn't look like it has that blur. But in fact this is accurate to the way film camera exposes an image. So let me go ahead and close this, and now we'll take a look at rotational blur. So what I'm going to do, right now I have this animation of the bike moving along. I'm going to go ahead and select it, and one way to delete the keyframes on this is simply highlight all the channels that have keys over in the channel box, right click, and choose delete selected. And that will delete all those keyframes. So now at frame one I'll go ahead and set a key, and then I'll move forward in time; select rotation, actually I want to move my pivot point to the back wheel here. It's not something you'd normally do mid-animation, but I want to setup this example so it looks like we've got a wheelie. And oops let me move this a little further back, that to there. OK and go ahead and key that. So we have that front wheel if I look at this section of the bike, it's moving in an arc, OK so I want to see that motion blur. If I go to a mid frame here, go ahead and key that. OK so I'm getting a little bit of motion blur now. In this case there isn't a lot of speed on the thing because I have this taking quite a bit of time, 14 frames to get up there. So if we want to exaggerate that just for the purposes of this example, we can go ahead and move that keyframe much closer. So any movements that happen more quickly will have a greater amount of motion blur. So this time go ahead and render it with the second key moved much further. OK so now I can see that motion blur quite a bit better there. And you'll notice if you look closely, there is very little blur on the back wheel, in particular this high contrast area. Let me zoom in here. Very little blur here because the rotation is happening at the wheel whereas the greatest amount of rotation or movement is happening here to these pixels in the front.