Improving Inverse Kinematics (IK)

As the manual states IK is either on or off.

There are several issues using IK by itself:

1: The only Parts that get Values are the XYZ Translate/Rotate. The rest of the Joints are a simulation and therefore have no Bend Values. Without Bend Values Joint Controlled Morphs (JCM’s) are not activated. Since almost all figures require JCM’s (or other modifications based on Joint Rotation) these are not applied so a Bend that should be modified during Posing is not and it then looks weird.

2: To overcome the lack of Joint Bend Values you can turn off IK which then puts Joint Bend Values into the various limbs which then activates the JCM’s. The problem with that is you have two things working against you (Joint Angle Precision and Poser Spline Curve). With IK On the Foot is at a fixed location in XYZ space. However once you turn Off IK then you need to figure out where to place the Foot starting at the Hip going down the Upper Thigh through the Lower Shin and finally to the Foot. Each of these requires the Angle to be Precise. Now where there is a Key Frame the Value is pretty close. However due to Posers Spline Curve function the in Between Frames as less Precise and that is where Foot Skating comes into Play.

3: To overcome this problem what you have to do is make your movement with IK On. Then turn IK Off, which sets the Key Frames for the limbs. Turn IK On again and then go the Animation Tab go to Resample Key Frames… Modify Current Figure and Make Key Frame every 1 Frames. What this does is put a Key Frame at each frame with the Values of all the joints that the IK moves through. Reduces to almost nothing the FOOT Skating problem.

4: The above is the Work around for the IK problem. AND if you are very Good OR very Lucky then you only have to make the movements once and be done with it. However very few things are done correctly the first time and you have to make tweaks to a movement and there is where the real problem is. IF you have bake down the IK as described above then you have LOST the original IK Key Frames and you have a lot of frame deleting to do to get back to the starting point.

Solution: Currently poser has a Layers Function built in (even though it has several problems itself). What I propose is that IK have a special Layers area where you have at least 2 Two layers. The First Layer would be the IK Key Frames. That way you have the original Key Frame movements available to tweak if need be. The Other Layer would be a Constantly updating Layer based upon the steps outlines above. If Word Processors can do spell checking on the fly there is no reason Poser cannot have a constantly updating IK layer. Added Bonus would be a way to make tweaks to the Final result by having a Middle Layer in-between the two listed above where I could move the Knee a bit to make it align better with what I want the movement to be. The other area that would be nice is if on the Dope Sheet you could define where the IK Layer should be applied (On) and where it should not be. I have made animations where I have used IK turned it off done non-IK movements and turn it back on. It is a bit of work and once you bake it down you are basically stuck, without restoring from a save point and redoing a lot of work to get to that point.

If the Poser team is really serious about animation (as that is the Top bullet point in what they are looking for in Beta Testers) then this should be a fairly simple addition. It would get rid of a work around which they seem so fond of. Such as Place an extra key Frame to prevent over shoot of the Spline Curve. Works OK Until you use a Function in Poser called Re-Time and Double the speed of an animation so it takes only 30 frames instead of 60. To make a 60 Frame animation into 30 means you have to toss out every other Key Frame and that means that Extra Key Frame you put in is lost and you are back to over shoot requiring a lot of time to reinstall those Key Frames. The other solution is to Fix the Break Spline to make it Curve both before and After the Break instead of Linear before and Curved after. You can find that in another thread of mine if you are interested.