Rigging Essay

A well made character rig works like an extension of the animator. It does what the animator expects, when they expect it.”

Jason Schleifer, from Cheryl Cabrera. 2008, pg.9

To animate any character in a 3D software program requires what is known as a rig. A rig is essentially a system of skeletal-like deformers (a series of linked bones and joints) which are then manipulated by control points (Valve Community, Web, 2011). This essay will discuss how the default rig in Softimage XSI works and compare it to another manually created rig which has been built by a 3D animator. It will then discuss the importance of creating a good rig and the correct procedure of going about such a creation.

Most modern 3D software packages come with default rig setups which may serve as a template to creating a new rigging setup, or may be perfected as they are. Rigs may, of course, be created from scratch (which allows for greater creative control over animating one’s character) but, for many, producing these character rigs “can be a daunting task” as serious attention needs to be paid to many different areas controlling deformation and animation. (Cabrera, C. 2008, pg75). Default rigs then, although they may not initially offer the same creative freedom a manually constructed rig can, are highly effective for many animators in creating animatable characters in a shorter period of time.

In order to setup a default rig in XSI, one first needs to create what is known as a Biped Guide (XSI User Guide). This is not the actual rig which will be used but rather, as the name suggests, a guide to setting up the final rig. It basically provides a skeletal reference which can be manipulated within the chosen character mesh. These reference points are moved until they match their respective features on the character mesh surrounding them i.e. finger bones are matched to the fingers on the mesh and so on. Below is an example of a biped guide:

One can also, at this point, toggle with the IK/FK controls within the guide in order to understand how the skeleton structure within the character will move which will essentially allow better animation of one’s character. IK/FK controls can be understood, at a basic level, as how the angles of bone joints relate with one another (with regards to parental hierarchies) in a 3D space. IK, or Inverse Kinematics, is “how the child node, as it moves, affects all the parents’ position and orientation values” (Web, 2011) and FK, or Forward Kinematics, refers to “the effect on the child nodes as the parent moves or rotates” (Web, 2011). Once these positions are all finalized, the biped guide can now be transformed into a proper rig. This rig is enveloped (effected upon) to the character mesh and now allows the character to be animatable.

This default rig, once weighted properly, is rather effective. It has a very similar structure to the human skeletal system in terms of its bone count/positioning and its joints and therefore allows for realistic movement (although it’s spine is probably too simplistic). It lacks, however, effective control points to animate the character on a more global scale. These must be created by the user which can in itself become a complex process. It also ‘behaves’ rather unpredictably when rotating the character’s torso areas and is not easy to resume the default position once these controls have been changed.

The second rig, which was sourced, is called Nano Man, created manually by an XSI user and outsourced as freeware. This rig has many of the essentials that the default rig contains but has extra features. Most useful is its global controllers which allow the user to manipulate larger areas of the character’s body simultaneously and with apparent ease as opposed to the default rig’s very limited global manipulation controls. In terms of its skeletal structure, it is also much more effective than the default rig, especially if one notes the spine. In this Nano Man, there are five spine bones (each with corresponding joints, roots and effectors) which significantly increases the amount of character flexibility available to the animator. The only real disadvantage of this rig is that, since it was created manually, it may take awhile for a new user to become familiar with the creator’s rigging style and how they chose to create control points and so on. Besides this, the Nano Man is an effective, quick to animate, rig which allows for great animation flexibility.

Finally, essential to rigging is organization. This goes all the way from character design, up until its animation. When designing the character, think of how it needs to move and therefore how it’s skeletal structure will look to achieve such animations. With this in mind, model the character with the skeletal features in mind. When it finally comes around to rigging the character, one can avoid a bad rig setup if one has designed and modeled the character effectively.

In terms of the rigging process itself, it becomes highly important in understanding how the hierarchies within the rig work. To make these hierarchies easier, it is vitally important to name the rig components. Kim Lee gives an example; “if your character is called Jester, name your bones jester-bone-01, jester-bone-02 and so on.” She also notes that naming becomes very important when merging one’s scenes together. (2002, pg. 165). Another useful technique is to universalize your control shapes – have all effectors as cubes, all roots as circles etc. This will make navigation between various different animatable parameters much easier.

In conclusion, this essay has defined what rigging in 3D software is and why it is so important to creating good animations. It has explored and discussed the default rig setup in Softimage XSI and has compared it to a custom built rig in order to understand how default rigs compare to manually created rigs (which concluded in the notion that a manual rig allows much more creative freedom and is therefore a better choice in the long run). Lastly, I have explored some tips and organizational strategies in rigging which allow for a more efficient process and which give the animator a greater grasp of his/her creation, subsequently allowing for a greater final product.

(1047 words)

Works Cited:

1. Cabrera, Cheryl. An Essential Introduction to Maya Character Rigging. 1^st Ed. Elsevier. Oxford, UK. 2008.
2. Lee, Kim. Inside 3Ds Max 4, Volume 1. 5^th Ed. New Riders Publishing. USA. 2002.
3. Real Illusion. What Is IK/FK. Web. http://www.reallusion.com/iclone/Help/iClone3/08_Animation/Motion_Layer/What_is_IK_FK.htm. 2011.
4. Softimage XSI 2011. User Guide. 2011
5. Valve Community. Rigging in XSI. Web. http://developer.valvesoftware.com/wiki/Rigging_your_Custom_Character . 04/03/2011.