WEBVTT 00:00.240 --> 00:05.070 Before we get to regain our own character, there's a concept I need to explain, and that's the difference 00:05.070 --> 00:11.700 between inversed kinematics and Ford Kinematics or IRQ versus F K for short. 00:12.330 --> 00:19.110 And I k we have already seen where if I select control and I move it around, all the other bones will 00:19.110 --> 00:21.270 follow that movement. 00:21.630 --> 00:28.230 OK, that's inverse kinematics, meaning it's figuring out the motion based on the inverse of where 00:28.230 --> 00:29.550 the point is ending up. 00:29.550 --> 00:29.910 Right. 00:30.450 --> 00:32.460 So that's one way to think about that. 00:33.420 --> 00:39.290 The other that we haven't seen yet is basically the origin of 3D animation. 00:39.300 --> 00:43.650 This is how everything was animated, like the original Jurassic Park. 00:44.010 --> 00:46.140 This was animated with Ford Kinematics. 00:46.620 --> 00:52.320 Now, if I wanted to put his hand on his head, I can just click it and put it on his head and now his 00:52.320 --> 00:53.280 hand is on his head. 00:53.610 --> 01:01.470 If I wanted to do that with Ford Kinematics, well, I would have to do is select the bone rotated up 01:01.470 --> 01:09.240 there, each bone individually, and I could eventually get it up there. 01:10.440 --> 01:10.860 All right. 01:11.190 --> 01:14.610 Same pose, but with two different types of rigs. 01:15.090 --> 01:17.550 And you can quickly see the difference, right? 01:17.790 --> 01:25.290 If I especially with the legs, if I move the center of gravity or the cog and I move it down. 01:25.600 --> 01:30.480 His shorts aren't following, first off, but his feet are staying in the same place. 01:30.510 --> 01:30.920 Right. 01:31.230 --> 01:33.090 That's because those are in the world space. 01:33.660 --> 01:38.640 They're not following the route of the body so he can stand on the ground. 01:39.360 --> 01:45.480 If I do the same thing with Ford Kinematics, everything moves together, right? 01:46.020 --> 01:50.730 Because it's all expecting to be adjusted from these joints. 01:50.730 --> 01:58.320 So I could move him down, then I would need to move both of these up and then move both of these down. 01:58.320 --> 02:01.380 And hopefully that would be somewhere on the ground ish. 02:02.340 --> 02:05.940 And this is actually how the original Jurassic Park was animated. 02:05.940 --> 02:09.200 They didn't have inversed kinematics back in the day. 02:09.510 --> 02:16.200 So this is kind of the origin of 3D animation is with Ford Kinematics and still used a lot today. 02:16.200 --> 02:18.630 Because let's think about it another way. 02:18.630 --> 02:26.640 If I wanted to have a nice arc with the hand, let's say I want it to rotate this like this. 02:26.640 --> 02:26.960 Right. 02:27.010 --> 02:28.050 Has a nice arc. 02:28.410 --> 02:36.570 If we're watching this joint, OK, it's following this arc because it's being rotated from this pivot 02:36.570 --> 02:37.500 away from itself. 02:37.860 --> 02:40.500 So there's a nice arc as he's throwing a ball or something like that. 02:41.040 --> 02:49.950 If I want to do that with inverse kinematics, I can bring the hand out here and then I would have to 02:50.490 --> 02:59.100 adjust the elbow to try to stay back here and then move this down. 03:01.190 --> 03:06.200 And the quick rig is actually kind of a different type of inverse kinematics, I could actually use 03:06.200 --> 03:06.920 the shoulder here. 03:08.000 --> 03:13.190 So it's trying to do a hybrid approach, but typically with an inverse kinematics, you would have to 03:13.850 --> 03:21.740 kind of position this thing and then reposition the elbow and constantly go between those two things 03:21.740 --> 03:25.740 to try to get that rotation like bothering a hand. 03:26.060 --> 03:28.190 So there's trade offs for each one. 03:28.220 --> 03:28.660 Right. 03:28.910 --> 03:32.520 And it's going to depend on what your character's going to be doing. 03:33.230 --> 03:33.800 Same thing. 03:33.800 --> 03:39.080 If you know that we saw with the feet not being on the ground, that's going to be the same thing with 03:39.080 --> 03:45.500 the hands in our earlier example of if his hand was touching a table and he was rotating, you know, 03:45.530 --> 03:49.970 this also wasn't following because it's in the relative space of his chest. 03:50.390 --> 03:51.920 It's going to follow his chest. 03:51.950 --> 03:53.600 His arms are following his chest. 03:53.600 --> 03:53.960 Right. 03:55.340 --> 03:56.720 Whereas his feet don't do that. 03:56.720 --> 04:03.700 So that's the space that it's in is a different component of it, right? 04:03.740 --> 04:05.510 It's a different component of emersed kinematics. 04:06.260 --> 04:12.140 So even though these both look the same, if we're rotating the chest like this, they're not right. 04:12.140 --> 04:16.730 And we can see why very quickly when we just select the rest and move it. 04:17.210 --> 04:17.990 We can't really do that. 04:17.990 --> 04:21.310 If we select the rest to move it here, it's not going to like that. 04:21.800 --> 04:28.040 So that's the difference between inversed and forward kinematics and how it's going to affect your posing 04:28.040 --> 04:30.860 and animation later on down the line. 04:31.640 --> 04:41.060 What what we will do is we will do an Ike setup and there are some rigs where you can actually switch 04:41.060 --> 04:41.420 between. 04:41.420 --> 04:41.920 I can. 04:42.740 --> 04:49.580 And they use very somewhat complicated math to figure out the vectors so that you can switch and it 04:49.580 --> 04:53.060 matches the pose, but we're not going to get that far into it. 04:53.070 --> 04:56.510 That's an advanced topic that maybe I'll discuss in another course. 04:56.750 --> 05:03.410 So to keep it simple, I just wanted to show you what Ford Kinematic says, because, you know, this 05:03.410 --> 05:09.170 is for the history of animation and for your your full understanding of what rigging is and animation. 05:09.170 --> 05:11.120 You need to understand both concepts. 05:11.510 --> 05:17.870 But for our rig, we're going to focus on Ike mostly, and that's how we're going to build our rig. 05:18.650 --> 05:24.140 In the next lesson, we're going to start to rig the Bones character that we modeled and textured in 05:24.140 --> 05:25.550 the previous parts of this course. 05:25.580 --> 05:26.300 Thanks for watching.