Ik problems

I’ve just spent several hours struggling to make one ik relationship, I have however found that if I mix FK with auto- Ik I can get some results but I would still like to know how to set the relationships manually though. I have tried the wiki stuff in every way I can interpret what is said I dont if some small detail was left out but I cant seem to get it right. if I apply ik constraint to thigh it connect to the pelvis/root an I not able the change it to the calf, if I select both bones and try I get an error IK tip cannot be connected to Ik root.

could someone give me an example of for instance thigh to calf or foot,
“baby steps if possible would be greatly appreciated”,

I have a max background where these things are rudimentry so not being able to do this is a bit frustrating

i use an uncomplicated biped setup with no controllers

When you add an IK constraint to a bone it makes an IK Chain of all bones HIGHER up the chain. I don’t understand why you would want to add an IK Constraint to the Thigh and not the Foot (or toe)? An IK on the foot would include the Thigh in the IK Chain.


but that it, I,ve tried all that, thigh is a child of and the pelvis but is not connected to any thing else but the calf but if I apply the contraint to the calf it disregards thigh makes the relation with the root/pelvis :frowning:

if I use the the auto Ik the relation are all right!!! but the only issues is that I can not translate the root for jumps and such

In Edit mode, select all the bones of the leg and in F9, Armature Bones tab, make sure that each bone has the “Con” (connectet) button on. If it’s off then the IK Chain will be broken. You should also check that each bone is parented to the one above it in the menu left of the Con button; Calf to Thigh, Thigh to Pelvis etc…


I use a single pelvic bone so connecting the thigh to the pelvis may be troublesome when its time for the model to be connnected shouldn’t a parent relationship be enough in that instance I’m accustomed to cstudio biped so I did not want to tray to far from that design and as I said auto IK get the relationship correctly, so does it not stand to reason that a the same effect should be possible manually it came show screens of the amarture on thursday to better illustrate the issue I’ll keep trying until then

is there a dummy object in blender that I can connect the biped to that won’t be affected by the auto Ik and allow me totranslate the rig until I,m able to figure this out

Yes, I was wrong about parent to pelvis (you probably use ‘pelvis’ as the bottom bone of the spine).

Here is an example with unnamed bones:


On your left the IK’s have no Target (Ctrl-I >> Without Target)
On your Right the Target is a Bone (Select Target bone and Shft-Select IK-Bone >> Ctrl-I >> To Selected).


thanks man I give it a shot this evening and again thanks

i got it to work, had to define the chain lengths thanks for the example proved valuable.

one more question I’ve been able to set ik on legs in max and have the knees bend ti kneel when I translate the pelvis downward is there are setting that might allow for this or a constraint of some sort it not heavily requirred just convenient

thanks in advance

Yes, you can add an Empty, or better a bone, just in front of the knee. Give the Thigh a TrackTo constraint and use that bone or Empty Object as the Target. That way, when walking the knees bend towards the TrackTo constraint and when it Kneels you can move the target to the Floor.


thank man, much appreciated

Is the control bone necessary in 2.4? I thought you’d just set a DoF on the knee joint so it can only bend one way.

I just answered the question:

is there are setting that might allow for this or a constraint of some sort it not heavily requirred just convenient

But, personally, I like those kind of constraints. I still like a stickshift and it’s going to take me a while to get used to 2.4’s transmission.


I must have doing it wrong but the trackto didn’t work for on the other hand the answer was slapping me in the face, from your example all the the time when I parented fligh% torso bone to the legs i saw that that ik bone with the target force the chain to bend at the needs when you pushed the torso down I’m still however trying to find and elengance way to have my target bone stay at the heel of the foot when I jump the character , I still have to go back and move it to heel before I can continue, was really hoping to avoid controllers though. could someone play with it a bit suggest ways to improve upon it thing that maybe can or should be done differently at present I get great root_pelvis/leg bahavior and there is two ik constraints add to the feet that interchange when I need some freedom again could be done better.

the armature it self may look a bit ragged but it’s a test and might also be animated forgot to shot off the ani-test and I,ve already uploaded it sorry :expressionless:

also sorry about the zip geocites apparently doesn’t like blends



I’m still however trying to find and elengance way to have my target bone stay at the heel of the foot when I jump the character

You can make them Child of ‘root_pelvis’ (I didn’t do it in this .blend because it would mess with the existing Actions).


thanks man I’ll have a look

thank alot for your help in this I have it working nicely, targets on the heel does’nt quite stay with the heel but but I’m satisfied

I added a bone on the floor that I call origin and parented the targets to that, which allows me alot of freedom with the pelvis.

some other questions though is something special that needs to be done to scale bone width and depths, can empties and other objects be treated as bones I developing these for a game and the md5 format is strictly skeletal, can copy edges from a model and have converted to bones for e.g. the edges that form then mouth of a character[/img]