# Hierarchy joint rotation outcome question

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I have a simple question, but the answer may require some good math comprehension. First, 'pose' = set of rotation values for every bone joint in the human body. I have one pose of a human skeleton standing on flat ground, and another pose nearly matching it, but with the lower body (below the hip) adjusted for standing on a 45-degree slope. Both poses have the legs and hip in the same basic stance, but adjusted to balance the character on the slope and to rest the feet on the ground correctly. If I mix half of each together to stand on a 22.5 degree slope, will the feet rest perfectly on the ground? By mix, I mean for each joint, the result is the sum of half of the rotation from both. If there's no guarantee of them being on the ground correctly, then no worries. I just want to make sure I'm doing everything correctly. I can find ways to fix the situation if there's no helping it. Thanks for any information edit: Wording [Edited by - Kest on September 5, 2006 3:03:53 PM]

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You can blend appropriately to accomplish what you want, but it is not going to work perfectly if you just, say, apply a simple weighted average of the rotation angles and translations. Getting animation blending to work can be a bit tricky. The folks who created MechWarrior chose an animation blending technique, with very good results on a problem similar to yours. You can see a report of their technique and results over at gamasutra (free registration required):

Animation Blending: Achieving Inverse Kinematics and More

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Thank you very much for that very useful link. I'll definitely look through it ASAP.

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Quote:
 Original post by grhodes_at_workYou can blend appropriately to accomplish what you want, but it is not going to work perfectly if you just, say, apply a simple weighted average of the rotation angles and translations. Getting animation blending to work can be a bit tricky. The folks who created MechWarrior chose an animation blending technique, with very good results on a problem similar to yours. You can see a report of their technique and results over at gamasutra (free registration required):Animation Blending: Achieving Inverse Kinematics and More

Hmm, after looking over that document, it appears that I'm already doing what they describe. My problem can be found in this text..

Quote:
 It is also possible to add more animation to different points within the existing space to help define that space more accurately. For instance, combining an animation of a character walking uphill and downhill may not necessarily result in an animation of the character walking on flat ground. In this case, one would further define the space with an animation of walking on flat ground. With these three animations, the blending space is now fully defined.

So I suppose they answered my question. That it will not always turn out with perfect results. They also mention something about adding minor IK touches to make the feet perfect, so I might try that.

Thanks again.

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