FK - spIk matching

#1

It’s not hard to matching FK to spIk, however in reverse, i can’t find a good way to do it. Anything would help, thanks

#2

Hi,
I haven’t tried this but here’s a guess at snapping spine ik (spik) to forward kinematic (fk) chain, hope its helpful.

 Suppose got fk chain with joints
 fk_1, fk_2, fk_3
 
 spine ik chain with joints
 spik_1, spik_2, spik_3, spik_4, spik_5
 
 Also suppose spik chain has curve with four cvs.
 cv_1, cv_2, cv_3, cv_4.
 
 
 Make a locator at each cv position example (loc_1 at cv_1 world position, loc_2 at cv_2, loc_3 at cv_3, loc_4 at cv_4)

These locators will be used to tell spik where to move for snapping. They don’t move yet so this is handled next.

 Parentconstrain (maintain offset on)  loc_1 and loc_2 to fk_1 (now rotating/translating fk_1 moves loc_1 and loc_2).  Parentconstrain loc_3 and loc_4 to fk_2.

The reason for parentconstrain over only point or only orient is so fk can stretch or rotate and it will still move locator. The reason for matain offset is so the locators start intially at cv locations. (also probably need to pick differently, which loc’s get moved by what fk joint)

Now the locators are moving with fk chain.
So when its time to snap spine ik to fk.

Translate cv_1 (or cv_1’s cluster/control) to loc_1, cv_2 to loc_2, cv_3 to loc_3 and cv_4 to loc_4.

 Hope this is helpful.
 
 Cheers,
 Nate
#3

ogbonna: Thank for your reply. But its only true for 1 degree curve
You know, i use 3 degree curve, so Cv will influence to each other. If you do like that, the position of spik joint will not match with current Fk Joint.

#4

You could set up the spine using my hybrid spine setup. Take a look, I haven’t met an animator that didn’t prefer this method after animating with it. No switching involved, just animate both control systems together, symbiotically.

http://www.youtube.com/watch?v=1TLchsw9ty8&feature=youtube_gdata_player

Btw, the video is in softimage. But everything is relevant and transferable to any package.

#5

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