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What would be some general rules in rigging?


Igor

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Hi

 

Im sure others can fill in the gaps so here it goes.

 

1: Model base pose:

 

You need to not use extreme poses for models you intend to rig.  The previz character can have nice S curves in the pose but save that for previz.  The actual model needs arms to the sides, fingers slightly apart, hands pronated, legs slightly apart, arms and legs slightly bent to aid IK natural bend.  I like to model eyes half closed as its easier for weighting.

 

2: Prep and check the model:

 

For the rigging stage to commence I will make sure there are no floating points, the model is 100% accurate and symmetrical for easier weighting (dependant on model) and that its scaled correctly, facing the correct way  and centred in world space on the floor.  I would also put the pivot at the feet.  Zero out the Cords, and check the Uvs are perfect. 

 

 

3: Name conventions

 

Its  good to name all joints and make sure you stick to a name convention.  You also need to keep consistent prefix or post how you define left from right joints. R_Shoulder, L_Shoulder for example.  This will aid in correct mirroring later on.

 

4: Joint placement:

 

You got to be careful not to follow the placement of joints to match real human anatomy.  The spine is located toward to back on a real human but it should be centred of the torso so as to not deform badly in either extreme.  Shoulders can be a pain but with proper placement its half the battle over, always inline with the armpit I found to work well.  Joints slightly toward the knee, and elbow aids the Ik, more so if your limbs are straight.   I also zero out cords as I go, more so the Controllers to enable (Reset PSR) for base the pose later.

 

5: Auto weighting Vs Manual

 

Auto weighting could well take you way longer to get  good results by tweaking weights than to flood a designated area or limb, then blend it.  Auto weighting is fine for starters but the best results come from flood weighting and smooth blending.

 

6:  PSR corrections to hide bad weighting.

 

Its tempting to fix weighting issues with PSR morphs, or commonly known as (Join Controlled Morphs), don't do this.  Make the weighting do most of the work, then clean it up with corrections after.

 

7: Check the rig is working as you go.

 

Don't assume all is fine, you could have some dependency issues which need sorting.  Its easier to find and fix a fault as you go than discover it days into a complex chain of events that is hard to unpack.

 

8:  Add your own controllers for Ik,

 

I like to add my own controllers and use them for the Ik.  Your get better positioning for them and they look better.  If they are spline based you can get more control over the shape, and move the pivot if needed, you cant with Nulls.

 

Thats enough for now, I let others add some.

 

Dan

 

 

 ArtStation    Website 

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2 hours ago, Rectro said:

...

4: Joint placement:

 

You got to be careful not to follow the placement of joints to match real human anatomy.  The spine is located toward to back on a real human but it should be centred of the torso so as to not deform badly in either extreme.  Shoulders can be a pain but with proper placement its half the battle over, always inline with the armpit I found to work well.  Joints slightly toward the knee, and elbow aids the Ik, more so if your limbs are straight.   I also zero out cords as I go, more so the Controllers to enable setset PSR for base pose later.

...

Thats enough for now, I let others add some.

 

Dan

 

Great list and 4 especially. I am always tempted to fudge spine or other joints toward human bone physiology.

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@Rectrocovered most of them accurately. i can only emphasize the proper joint placement. i‘ve seen many rigs where they were too close to human anatomy, and while in general it’s a good idea to work anatomically correct, always think about how this will deform when the joints get bent. most of the time, right in the center of the volume of your mesh is the better choice. 

 

also i‘d like to add the importance of joint alignment. always make sure the joints in one chain are aligned properly, for arms and legs always with z pointing down the chain. you can choose another orientation, but since spline ik for instance is set to have z as the twist axis by default, it’s a good habit to choose z, it just saves you an extra step later on.  same goes for controller orientations: have them match your joint orientations. like with any rules in life, there‘s exceptions where it makes sense to break the rule, just make sure you know what you’re doing and why you’re doing it.

 

also, like dan already mentioned, use correctional morphs as your last resort, you can do a lot in problematic areas like shoulders and elbows with helper joints, that are placed cleverly and share orientation values of 2 or 3 other joints. drive those with constraints and/or xpressions.

 

proportional scaling will work fine with most setups by default, in case if spline ik, if you wanna scale the character as a whole, don‘t scale the splines with it. put them in another hierarchy so they don‘t get scaled with the rest. if you want to scale parts of your rig unproportionally, you need to have the joints you want to scale floating, that means not connected in a hierarchy. and also scaling won‘t work with any other skinning mode than linear, keep that in mind. 

 

 

most of these rules apply to any DCC, but some of them like the scaling and z-axis thing are c4d specific...

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I think the guys above me summed up perfectly everything!!

My little tip is more on the finishing touches to an already rigged character.
Sometimes, a jiggle deformer helps a lot in some effects! Specially if there are more baggy/big folds on clothes.
Doing a vertex map and using that as a restriction for jiggle deformer, adds this nice extra layer to a character movement, without needing to have cloth simulation, etc.

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4 minutes ago, Igor said:

THanks guys, much appriciated. I think Ill have few more question about rigging as I go. Something like when to use IK or when to use FK? Are there rules about that? 

They are situational, ideally, on a professional rig, there will always be a IK/FK switch to some parts of the body, specially legs and arms.
For walk cycles, jumps, etc... you would use IK.
If a character is sitting, and is bouncing his/her legs back and forth, then switch to FK, as a simple rotation animation would be awesome (doing this kind of movement using IK is a nightmare)

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On 9/7/2021 at 12:53 PM, Igor said:

Thanks guys, much appreiciated. I think Ill have few more question about rigging as I go. Something like when to use IK or when to use FK? Are there rules about that? 

Flima is right, most pro rigs use IK/FK switching for the arms and legs. In my professional experience I hardly ever use FK for legs nearly always IK unless the character is doing something like kicking a football. When it comes to walks, waving and jumps I would use FK for the arms and IK when a character is reaching for something or pushing something.  I must admit I tend to use IK for everything if I don't have much time, this is referred to as 'goal-based' animation.

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Thanks @GazzaMataz, at the moment I am stuck with the issue I cannot debug. For some reason my shoulders are twisted when the elbow pin is on the position it should be...

image.png

 

when I move that pin down, shoulders look much better...

 

image.png

 

any ideas why this is happening? 

U-Render Quality Assurance Specialist | Core4D Contributions

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When creating an arm rig you want to create a collar joint (collar bone), a shoulder joint, and elbow joint and a wrist joint. You should create the IK chain from the shoulder joint to the wrist joint and add a pole vector which swivels the arm. Make sure that there is a slight bend in your arm for the IK to work itself out otherwise if the joint chain is dead straight you will have the arm bending the wrong way (mind you for some characters you might want this).

 

The pole vector should swivel the arm at the elbow up or down and move the shoulder joint somewhat. Make sure that you have your joints aligned correctly since this as Everfresh and Rectro said will give you even more problems.

 

Since your imagine is quite dark I cannot really see what is happening to the shoulder joint… HTH

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1 hour ago, Igor said:

Thanks @GazzaMataz, at the moment I am stuck with the issue I cannot debug. For some reason my shoulders are twisted when the elbow pin is on the position it should be...

 

 

when I move that pin down, shoulders look much better...

 

 

any ideas why this is happening? 

Need to see the joints.  You should have the Chest/L_Collar/Bicep/Forearm/L_Hand  The Ik should be between the Bicep and Hand, then Pole Vector needs to be added.  As for IK/FK blending/ I found using two rigs works best, your need to do a little Xpresso to show/hide controls between IK/FK.  The easier way in C4D is to use Pose Morph, this is all learnt from Cinevercity via Bret Bays tutorials.

PS @GazzaMataz cover much of what I posted after his post.

 

image.png.ca0c17fca82df423c4c54e410a0f9844.png

 ArtStation    Website 

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