JOINT BEND-RIG

68 votes
Version: 
2
Date Updated: 
04/15/2008
Author Name: 
Matthew Dicks

 

 Joint Bend Rig Elbow Setup PreviewJOINT BEND RIG Shoulder Setup Preview

A Tool to greatly speed up and simplify the process of skinning the joints of characters,especially shoulders and hips which are notoriously difficult to skin. THE NEW VERSION 2 OF THE JOINT BEND RIG HAS A BIAS CONTROL TO CONTROL THE AMOUNT OF TWIST IN THE JOINT

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Additional Info: 

The joint bend-rig is designed to quickly set up skinning for bending and twisting motions.
Just merge the bend rig in the max file with your current scene making sure to get all of its parts. ( i recommend grouping it before merging to ensure a clean merge ). Or use it as part of a new rig that is being set up.


LATEST UPDATE 9-18-08

There are now 2 new beta versions of the bend rig available that improve on the old versions in several ways. I am calling them version 3 and version 3.5 optimized.

VERSION 3

-Version 3 fixes an issue with the bias control that was occuring with the old version 2. The bias controls in version 3 now work perfectly at all angles and bias values. It also has 2 new types of bias controls that allows you to control the twist and tilt from the center of the bend in addition to bias controls for both ends of the cross sections. This gives a great deal more control over the type of twist and bend that is happening in the joint.

Version 3 also has been completely rebuilt and now has a more streamlined design for better performance than version 2. There are a couple of setups in the bend rig 3 file that allow you to see how the bend rig can be set up and the effects of the new bias controls can be seen by playing around with the values at different bend angles. The setup for a hip joint can still be seen in the file for version 2 but i recommend using version 3 for serious projects.

VERSION 3.5 OPTIMIZED

-version 3.5 optimized is a stripped down optimized version of version 3 that uses about 85 percent scripted wiring to acheive the bending and twisting. The idea behind version 3.5 is to optimize and improve the performance of the bend rig when using multiple bend rigs on a character by using mostly scripted wiring to acheive the bending and twisting motion as opposed to mostly position and orientation constraints that are used by version 3. It can be used when the advanced level of control given by version 3 of the bend rig is not needed.

-It differs from version 3 in that it only has one bend arm rather than 2 and also it only has one bias control. This will be enough for many rigging situations.

-To use the bend rig in the opposite direction one just has to mirror it while grouped.

Version 3.5 optimized also has several other features that allow even greater control over its performance.

>DELETABLE CROSS SECTIONS
First any cross section ( except for cross sections 1 , 5 , and 9 ) can be deleted from the rig without affecting the proper bending and twisting of the rig. This means less objects being calculated in the bending motion. In many cases skinning to just 5 cross sections ( 1, 3 , 5 , 7 , and 9 ) will be enough to create good deformation or even 3 ( 1 , 5 , and 9 ).

As long as cross sections 1 , 5 , and 9 are not deleted or altered the bend rig will still function properly.

The bias cross section and bias control can also be deleted if they are not needed. ( to delete the bias cross sections i recomend first deleting the 2nd one then the 1st then the 3rd)
The bias control will still work if the bias cross sections are not there but if the bias control is not needed it can also be deleted. An example of the bend rig 3.5 with deleted cross sections is included in the max file.

I have fully tested both of these versions and have encountered no issues, but i recommend testing them out fully yourself before using them for serious projects.

I am keeping bend rig 2 file available for now because it still has the example setups for shoulders and legs. You can still use that to test out the bend rig but i reccomend using version 3 and 3.5 for serious projects. I may do a few extra example setups that show the bend rig being used for all joints on the body including one that shows the optimized bend rig being used to skin all of the joints of a hand.

Looking at the video tutorial for the fast setup of a shoulder joint will give you a good idea of how it can be set up.

The bias controls have custom attributes in there modifier stacks that give a great deal of control of twisting and tilting of the bend cross sections. The effect of changing the bias settings can be viewed by changing the bias settings at different angles in the animation on the shoulder and pelvis that are already set up in the max file.

This bias custom attribute can also be wired to a reaction with joints enabling different bias settings at different angles much like biped twist poses. There is a specific technique that i have found is necessary to do this though. I discuss this in a document included with the file.

The bend rig has two types of cross sections. A set that creates the bending motion and an extra set of cross sections that can be skinned to, too distribute the twist further into the limb itself which constitutes it's own twist links system for effects like upper arm twist, wrist twist, thigh twist, etc. The length of the cross sections can be adjusted by moving the bias control in and out.

This can also be used in conjunction with twist links that are already set up on your rig, say if a bend arm were linked to a twist link of your rig the twist links of the bend rig can be used to blend between them.

For examples of the bend rig used to setup a hip joint see the older versions zip file which i have still made available only so that the example setups in the max file can still be accessed.

Note: most joint bend rig parts have explanations in the object properties user defined area. Also the text in the viewports have explanations in there object user defined properties.

Just merge the bend rig in the max file with your current scene making sure to get all of its parts. ( i recommend grouping it before merging to ensure a clean merge but I also reccomemd ungrouping it after the merge). Or use it as part of a new rig that is being set up.

The bend rig has two rectangle bend arms and a com joint ( which is dark blue in the max file). The bend arms are what control the bending motion of the cross sections and these are what should be linked to your rig parts ( example: clavicle and upper arm) the com joint controls the center of the bend and you will most likely want to link it to the parent joint ( example: clavicle) the cross sections are not meant to be moved themselves but only controlled by the bend arms and com. You will also notice that if you move the bend arms the bend rig cross sections will stretch, good for stretchy joints ( version 3 only ) . Initially the bend arms are linked to the com joint and the whole bend rig can be moved by moving just the com joint.

To resize it position it and clone it , group all of its parts and scale it uniformly (i recommend ungrouping it afterwards , note: also when cloning it do not move it far or use edit clone. If it is moved to far when cloning some of the parts may be left behind, I thnk this is some kind of cloning issue in max.

If you move it only slightly when using shift copy it will clone fine. Then you can move it to where it needs to be). Another note about grouping: remember that if any part of what you are trying to group is linked to something outside of the group the grouping will not be allowed so if you have linked the bend rig arms and com to something (i.E parts of your rig) already you will not be able to group the whole bend rig as one group)

The cross sections are what are meant to be skinned to and are what create the bending of the joints. Skinning to the bend arms is optional since you will probably just skin to your original rig for these joints (example upper arm and chest)

Skinning elbows, knees or any kind of joint with the bend rig, is fast and easy. Easily create deformations with nice creasing at any angle. The joint bend-rig is a series of objects that create an accordion like bending and twisting motion that is constant and even. It enables the maintaing of volume throughout a twisting and bending motion when a mesh is skinned to it. Thus even with little or no adjusting of envelopes or vertex weighting, when the bend rig is properly positioned in a joint, good deformations can be obtained. And when manual adjustment of weights is necessary the process is much more intuitive. Unlike spline ik which can give udesired random rotations around its links at different angles, the bend rigs bending and twisting motion at any angle is always constant and even. Also unlike spline ik, the bend rig can stretch. The joint bend-rig can be linked to any rig that has already been set up such as a biped or any rig that has already been set up for a character. Or it can be used as part of a new rig that is being created.

The file includes a max file with the bend rig with brief notes in the veiwport on how to set it up(basically what parts to link to what) it also includes some skinning examples showing the basic skinning. Just start rotatiing and moving the arms of the bend rig and you can get an idea of how it should be used. The cross sections of the bend rig are what create the bending motion and what should be skinned to. They are not meant to be moved themselves but are controlled by the rotating and moving of the bend arms and com (both marked with text in the viewport). The center of the bending motion can be changed by moving the com or bend arms ( version 3 only ) .

One more note: good creasing can be acheived using the bend rig alone but add to this the power of the relax and push modifiers and creases are even easier to control. An example of using the relax and push modifier with the bend rig is given in the max file.

I will try to be posting some more imfo and tutorials shortly. This has been tested on a character that i have recently set up but please let me know about any issues that are found.

The example setups from the older version of the bend rig can still be accessed here:

Also if anyone would like a version of this for an earlier version of max please let me know and i will see if i can produce one.

VIDEO TUTORIALS

Http://www.Veoh.Com/videos/v6436271gmqzg72x
http://www.youtube.com/watch?v=wKBjLm42lwY

You may have to press the button a few times to view the third link. Also the maximize button might not work. You should be able to download the video tutorial with real player or any flash player that can download from the web. Still working on a better solution but at least those who cannot access veoh or youtube will be able to view it.

Version Requirement: 
max 8 and up
Video URL: 
AttachmentSize
BEND_RIG_VS_Standard_BONES_1.avi1.17 MB
BEND_RIGGED_Shoulder.avi1.32 MB
char_joint_motion_bnd_rig_tst1.mov2.01 MB
Bend_Rig_in_Shldr_demo_smllst_3.avi4.69 MB
Shoulder_Viewport_preview.avi1.87 MB
Pelvis_Bend_Rigged_avi.avi987 KB
BEND RIG 3 AND 3.5.zip768.59 KB
OLDER VERSIONS_WITH EXAMPLE SETUPS.zip1.48 MB

Comments

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EricChadwick's picture

This rig looks cool. Like

This rig looks cool. Like Brad though, I couldn't read all in all caps, makes my eyes bug out. I had to copy/paste your text into a tool that converts all-caps to initial-upper, then I read it. I can send you my "translation", if you want to edit your inital post.

3D Game Artist - http://ericchadwick.com
Admin for the Polycount wiki - http://wiki.polycount.com

MATSCRPTART's picture

GOT YOU

GOT YOU !!!!!!!!!!!!!!!!!!!

Actually its an old habit of mine. I find it just easier to read capitalized letters. But I Understand your point.
Thanks.

Brad Noble's picture

Could I make a comment? 

Could I make a comment?  Please stop using the caps lock!

THERE'S NO NEED TO SHOUT.

MATSCRPTART's picture

JUST A QUICK NOTE: THE THERE

JUST A QUICK NOTE:

THE THERE SHOULD BE NO ISSUES SKINNING TO THE BEND RIG AFTER IT HAS BEEN SIZED USING SCALING AS LONG AS THE BEND RIG IS SCALED UNIFORMLY. I DO NOT RECOMMEND ANY
NON-UNIFORM SCALING OF THE BEND RIG.
ANY WHO ARE NERVOUS ABOUT SCALING THOUGH CAN ALWAYS USE AN XFORM ON THE BEND RIG AS A GROUP. BUT YOU WILL PROBABLY WANT TO COLLAPSE THE STACKS OF ALL BEND RIG OBJECTS AFTERWARD TO GET RID OF THE XFORM GIZMO IN THE VIEWPORT.

BUT THIS SHOULD NOT BE NECESSARY. I HAVE NOT YET ENCOUNTERED ANY PROBLEMS WITH SKINNING TO THE BEND RIG AFTER IT HAS BEEN SIZED USING UNIFORM SCALING.

MATSCRPTART's picture

The tutorial is also on

The tutorial is also on youtube here

http://www.youtube.com/watch?v=wKBjLm42lwY

hopefully all will be able to view it there in the meantime while I work on a better solution.

Matthew

MATSCRPTART's picture

About the Shoulder

About the Shoulder twist

GLAD YOU MENTIONED THIS. Interestingly the gif preview of the shoulder movement shown above is actually using the first version of the Bend Rig and no other rig. This was just a quick test setup just used to show the bend rig alone.

For an even better example of the deformation that can be used by using the bend rig alone see the following link.

http://www.veoh.com/videos/v14263876T9HpZHa7

This test on a make human model, was done using just the Advanced Version 2 of the bend rig and no other morph targets or modifiers or rigs. Although some morph targets could be added to refine some of the shapes of the movements, It is a very good starting point and holds well I feel by itself. Because The advanced Version of the Bend rig was used in this test, I was able to get better control of the twist in the shoulder.

The Bend Rig of course must be used in conjunction with the main rig for your own character. When you use it in conjunction with your own rig you will have a few great options to control the amount of actual twist in the shoulder joint.

1- The Advanced Version of the Bend Rig that is included with the max file has a bias control which has a custom attribute which can be adjusted to control the amount of twist in the bend rig. Values from 1 - 50 should be used in most cases. The advanced version also has an extra set of bias cross sections to blend the movement into the limb of the joint. The Bias control can be moved in or out to adjust the length of the cross sections and it can even be linked to a seperate object if desired.

2- Although the Bias controls and cross sections can be used to control the amount of twist in the joint by itself, It really is designed to be used in conjunction with the twist links of your own rig.

You can attach the arm of the bend rig to your own upper arm twist link system of your rig. This way you can control exactly how much the Bend Rig twists. Say you are using a biped
Say you have 4 twist links in your upper arm. You can attach the bend rig arm to the first twist link in the upper arm which hardly twists at all and there will almost no twist in the shoulder. And of course as you attach to a lower and lower twist link of the upper arm you will get more and more twist in the shoulder area of the bend rig. Then you can optionally skin to the extra bias twist links of the bend rig to blend between the bend rig and the twist links of your own rig.

3- Finally you can adjust the Deformations of the bend rig with morph targets. If you choose to. But in my experience I can get pretty much about 90 to 95 percent to where I want the deformations to be with the bend rig alone, By spending a few more minutes fine tuning weights of verts, to the cross sections.

In summary I think using the bend rig is a great way to get a more solid starting point for deformation with a lot less work than would have been gotten just using the skin modifier alone. Which is the whole point. To give as good a starting place for modelling the movement as possible. The Bend Rig is not going to do all the work but it can get you most of the way there.

Matthew

MATSCRPTART's picture

I will try to work on a

I will try to work on a better way to access the video tutorial. The Tutorial file is really way too large. Unfortunately I used a cheap free screenrecorder to do it. I have not been able to compress it very well and still keep the quality to be able to see the words and stuff very well. I will have to see what I can come up with.

Matthew

IN_human's picture
exhale's picture

Veoh.com is not working in

Veoh.com is not working in my country. :( Do you upload to rapidshare,megaupload .etc

MATSCRPTART's picture

Thanks for the feedback. I

Thanks for the feedback. I would hope everyone agrees that the ultimate goal should be 0 time to setup a character with 0 percent learning curve necessary. There is no virtue in making anything more complicated than it has to be especially from a production standpoint. I think for most artists we want to get to the creative artistic part as fast as possible, and spend as little time on the tedious stuff as possible. I look forward to lots of revelutionary ideas in this direction.

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