spine IK rigging problem

# 1 13-10-2011 , 07:13 PM

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Hi. I have been trying to do spine IK rig in the book “Body Language/Eric Allen&Kelly Murdock”. (The tutorial starts at page 58. )
I think I have followed the instruction the book says precisely but run into the problem. I’m at the point I added stretchiness to the spine joints by following the instruction in the book. (basically by connecting the necessary nodes in the Hypershade. )
Then when I set the second term option in the condition node to “1”, one of the joint in the spine joint chain disappeared. (there is 7 joints in the chain) I later found out that joint 3 and 4 have ben overlapped. When I switched the option back to “0”, then it goes back to normal spine joint chain. I have re-followed the instruction to find out what I did wrong but so far, no luck. I really want to find out why this has happened and what I did wrong. Any idea?
Thanks.

-naoki

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# 2 13-10-2011 , 11:29 PM

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Okay firstly, can you post some images of what you are doing, we cant see the book

cheers
Jay

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# 3 14-10-2011 , 03:15 PM

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Okay firstly, can you post some images of what you are doing, we cant see the book

cheers
Jay

Originally Posted by Jay

Oops, sorry, Jay. I forgot to attached the images. Now I attached the images.

I'm doing the spine IK rig tutorial in the book. (see attachment book_01, 02) When I finished "adding a stretchness switch", I noticed that the my spine chain looked like this. (attachment joints_b) It was originally like this. (attachment joints_a)
What happened was that when I changed the "second term option" of the condition node "StretchCond" (see attachment hyp_sha)from 0 to 1, the joint3 and 4 overlapped andn thus, the whole chain got shorter, as you could see. Chain structure itself is pretty simple as you know. (see attachment grh_ed)
I just can't find what I did wrong to cause this problem. If you could point out, I'd really appreciate that. Thank you.

-naoki

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# 4 14-10-2011 , 04:20 PM

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Well reading from the first page, he says that with the Auto Simplify Curve option enabled it will change the shape of the spine a little. And you can lessen the effect on the oriented joints by simplifying the curve of the joint chain (straightening).....

read part 1 again so this is clear first of all. With rigging it does take a bit of a mindset to get round what is going on and why things do what they do. I'll have a look thru this stuff and see if I get any probs and get back to you later. It should be pretty straight forward but as you are doing a rig thats for back stretch there maybe an easier way

Jay

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# 5 14-10-2011 , 04:37 PM

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Well reading from the first page, he says that with the Auto Simplify Curve option enabled it will change the shape of the spine a little. And you can lessen the effect on the oriented joints by simplifying the curve of the joint chain (straightening).....

read part 1 again so this is clear first of all. With rigging it does take a bit of a mindset to get round what is going on and why things do what they do. I'll have a look thru this stuff and see if I get any probs and get back to you later. It should be pretty straight forward but as you are doing a rig thats for back stretch there maybe an easier way

Jay

Originally Posted by Jay

Thanks for quick response, Jay. Yes, I actually read that part you mentioned but I didn’t think it was “change the shape of the spine a little”. I thought the joint chain might get a little straighter or something. I didn’t consider “visibly missing one joint” as a little change.
Anyway, I didn’t attach the next page but the picture in the book clearly shows seven joints, no joints overlapping. I also noticed something in the picture of the hypershade I attached. I noticed that there are plus-minus average nodes connected to each joint. In the tutorial instruction, they never mentioned those nodes (until few pages later). So, I started to think what they saying doesn’t really correspond to what they show. I know stuff like this happens all the time in any how-to books so I’m not upsetting or anything but it’s a bit frustrating.
I have gone through “inspired 3D character set up” book long ago and there were so many mistakes in that book. (from just a minor typo to totally wrong naming, etc. It gave me such a hard time especially when it came to expressions… because spelling is almost everything there.)

Anyway, I appreciate your response. If you have a time to go through it and could find something and tell me about it, it’d be great. Thanks again.

-naoki

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# 6 14-10-2011 , 04:46 PM

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Yeah he mentions in the chapter there, that he'll explain the other nodes later -not very helpful as its all related here on these pages.

I'll have a look, I know a simple way to do the same thing so I'll see about writng it up.

If I were to recommend a book on rigging it would be Character Creation in Maya by Chris Marafi -just excellent. I have had this book for years. Its still available. I learned alot from it and use certain parts of it on my own rigs. I use the different parts of things Ive learned over the years and applied them to my rigs so I get the best of everything and its also very simple. You also may want to download our latest tutorial Volume 3 of Surfing with the Alien. I did a whole rig setup in 9 chapters including cloth, making the whole thing painless to do.

anyway I will look at this and see if I can shed some light on the matter for you

Jay

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# 7 14-10-2011 , 05:09 PM

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Yeah he mentions in the chapter there, that he'll explain the other nodes later -not very helpful as its all related here on these pages.

I'll have a look, I know a simple way to do the same thing so I'll see about writng it up.

If I were to recommend a book on rigging it would be Character Creation in Maya by Chris Marafi -just excellent. I have had this book for years. Its still available. I learned alot from it and use certain parts of it on my own rigs. I use the different parts of things Ive learned over the years and applied them to my rigs so I get the best of everything and its also very simple. You also may want to download our latest tutorial Volume 3 of Surfing with the Alien. I did a whole rig setup in 9 chapters including cloth, making the whole thing painless to do.

anyway I will look at this and see if I can shed some light on the matter for you

Jay

Originally Posted by Jay

Thanks Jay. I should have waited a bit longer then…. I just ordered this book “body language” through Amazon yesterday. Geez. I was also curious about the book you mentioned “Character Creation in Maya”. I read the review and it was kinda mixed review so I decided to go with “body..”. (That’s why I hate buying a book online because I can’t flip it through and see what’s in there. Local book store here doesn’t carry much CG stuff.)

Anyway, thanks for the tip. I’ll exchange the book once the body language gets delivered.

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# 8 14-10-2011 , 07:22 PM

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i read scanned pages that you posted. Book is correct. you are getting problem in making a switch for stretch and when you keep the condition to 1 joints get overlap or disappear . i think you have done a mistake in renaming the things, make sure you have correctly renamed the Ik handle, effector and other things as mentioned in book. sometime it happens when we try to fix things in hurry and we do small small mistakes. ok. So just repeat your process once more or check if everything is renamed properly and all nodes connected in right manner. user added image

good luck!

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# 9 14-10-2011 , 10:12 PM

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i read scanned pages that you posted. Book is correct. you are getting problem in making a switch for stretch and when you keep the condition to 1 joints get overlap or disappear . i think you have done a mistake in renaming the things, make sure you have correctly renamed the Ik handle, effector and other things as mentioned in book. sometime it happens when we try to fix things in hurry and we do small small mistakes. ok. So just repeat your process once more or check if everything is renamed properly and all nodes connected in right manner. good luck!

Originally Posted by puneet.3d

Alright, Jay. I thought I re-checked everything but I'll do it over again. Thanks.

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# 10 17-10-2011 , 04:54 PM

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i read scanned pages that you posted. Book is correct. you are getting problem in making a switch for stretch and when you keep the condition to 1 joints get overlap or disappear . i think you have done a mistake in renaming the things, make sure you have correctly renamed the Ik handle, effector and other things as mentioned in book. sometime it happens when we try to fix things in hurry and we do small small mistakes. ok. So just repeat your process once more or check if everything is renamed properly and all nodes connected in right manner. good luck!

Originally Posted by puneet.3d

Hi Jay. I just let you kow that I re-tried it again and now it's working. As you have mentioned, I think I have done something wrong in the process. Now the joint in the chain doesn't overlap or anything.
Anyway, I just wanted to say thank you.

-naoki

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