Hash Fellow robcat2075 Posted April 17, 2012 Hash Fellow Share Posted April 17, 2012 What is IK Damping? It has something to do with avoiding "IK pop"? I can't see an obvious difference when i have it ON or OFF. Quote Link to comment Share on other sites More sharing options...
serg2 Posted April 17, 2012 Share Posted April 17, 2012 EXAMPLE IK_DAMPING.prj Quote Link to comment Share on other sites More sharing options...
Hash Fellow robcat2075 Posted April 17, 2012 Author Hash Fellow Share Posted April 17, 2012 EXAMPLE IK_DAMPING.prj Can you tell me more about that? They behave differently, but they both have a bad flip at some point. I'm not sure one is more advantageous than the other... Thanks! Quote Link to comment Share on other sites More sharing options...
serg2 Posted April 17, 2012 Share Posted April 17, 2012 I myself have long been trying to understand it. And also see that when the parameter Ik dumping occurs more chaos IK_DAMPING2.prj But the difference can be seen. Let us try to understand why this is Quote Link to comment Share on other sites More sharing options...
Hash Fellow robcat2075 Posted April 17, 2012 Author Hash Fellow Share Posted April 17, 2012 Here's an old CGTalk thread that suggests it has something to do with the "pop" that happens when an IK chain is pulled straight but they don't explain much about it. http://forums.cgsociety.org/archive/index.php/t-115396.html Here's an old paper that uses "damped" in connection with the various formulas for solving IK positions, but it's overly technical. http://www.google.com/url?sa=t&rct=j&a...5djZsMMZOheoHxA Quote Link to comment Share on other sites More sharing options...
Hash Fellow robcat2075 Posted April 17, 2012 Author Hash Fellow Share Posted April 17, 2012 I myself have long been trying to understand it. And also see that when the parameter Ik dumping occurs more chaos IK_DAMPING2.prj But the difference can be seen. Let us try to understand why this is So far, I guess I'm not missing much by not using it. Quote Link to comment Share on other sites More sharing options...
itsjustme Posted April 17, 2012 Share Posted April 17, 2012 From the Technical Manual: Damping Visible: Sometimes, Advanced, Default: 5, Min: 0, Max: 1e+008. Damping controls the motion of the chain. It damps the springs that force the chain towards its target. The faster the spring tries to pull, the more the damping resists the motion. A higher number slows the oscillations more. Stiffer springs require higher damping values. I haven't rigged anything where this proved useful. Although I'm sure there are times when it would be. As for controlling "IK Pop", the tutorial on Exponential Decay might help...I posted it a few weeks ago. Hope that helps. Quote Link to comment Share on other sites More sharing options...
Hash Fellow robcat2075 Posted April 18, 2012 Author Hash Fellow Share Posted April 18, 2012 From the Technical Manual: Damping Visible: Sometimes, Advanced, Default: 5, Min: 0, Max: 1e+008. Damping controls the motion of the chain... Where does this numerical parameter show up? i have Show Advanced Properties ON and I haven't seen it. Quote Link to comment Share on other sites More sharing options...
itsjustme Posted April 18, 2012 Share Posted April 18, 2012 LOL! I screwed up, Robert. I just did a quick search in the Technical Reference for "damping"....that was for hair, unfortunately. Here's the actual entry for IK damping: IK Damping Default: 180°, Angle. Damping controls the way a kinematic constraint finds its solution when set to support limits and damping. The normal way for the solver to operate is to prioritize the movement of the bones at the end of the chain first. This is normally the most natural way. However, sometimes it is preferred to have the last joint of a chain to behave rather stiffly, forcing the solver to prefer to move the next bone up. Damping allows this to be accomplished. By setting the damping on the last bone to a small number it will make the last joint stiffer. The damping value represents the number of degrees the bone is allowed to rotate in one iteration of the solver. So small values resist movement more, and large numbers resist movement less. By default damping is set to 180, which is totally free movement Sorry about that, I did that too quickly the first time. Quote Link to comment Share on other sites More sharing options...
itsjustme Posted April 18, 2012 Share Posted April 18, 2012 And here's the entry that I think explains it (from the Technical Manual): Kinematic Constraint Limits tab The kinematic constraint can be set to support angular limits on the bones within the chain. To do this check ”Support limits and damping” on the Limits page. When checked the software will enforce the limits at each step of the solving process. In this way if the goal may be reached with the limits enforced, it will succeed. If not checked the limits are only enforced after a solution that meets the goal is found. This often results in the goal not being reached even though a solution may be possible. Damping can be set on any angular limit. That includes “spherical limits” and the “euler limits”. The normal way for the solver to operate is to prioritize the movement the bones at the end of the chain first. This is normally the most natural way. However, sometimes it is preferred to have the last joint of a chain to behave rather stiffly, forcing the solver to prefer to move the next bone up. Damping allows this to be accomplished. By setting the damping on the last bone to a small number it will make the last joint stiffer. The damping value represents the number of degrees the bone is allowed to rotate in one iteration of the solver. So small values resist movement more, and large numbers resist movement less. By default damping is set to 180, which is totally free movement. When limits and damping are supported, the solver can also compute roll. Do this by checking “Compute Roll” on the limits page. Computing roll on a bone can help accomplish a kinematic solution that may not be possible without either the option or by setting the roll by hand. This can be useful in mechanisms such as the human elbow where it is preferable to roll the bicep rather than allowing the elbow to rotate sideways against the direction of the natural hinge joint of the elbow. This can be accomplished by placing angular limits on the forearm to restrict its movement naturally, then allow the kinematic solver to compute the roll on the chain, which can roll the bicep within its roll limits to accomplish the requested goal. ---------------------------- EDIT ---------------------------- As I said, I've never had a need to use it, but I'm sure it would be useful in some situations. Quote Link to comment Share on other sites More sharing options...
Hash Fellow robcat2075 Posted April 18, 2012 Author Hash Fellow Share Posted April 18, 2012 Hmmm... I had thought IK regarded bone limits all the time Quote Link to comment Share on other sites More sharing options...
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