Archive for the ‘Art Theory’ Category

Rigging Fundamentals

Friday, March 2nd, 2012

A student of mine, making a light saber animation, asks how can he gain more control over an object that is constrained to a parent, is keyframed, and would like to edit it further, but cannot figure out how to override the constraint. I didn’t want to talk about constraint blending, as there are complications with that and are difficult to explain. Instead, I wrote a diagram on the white board describing what all rigs should be, at a fundamental level. The theory is simple, all manual animation, meaning the transforms are keyable by the animator, are the last child in a hierarchy of automated tasks, such as constraints. It looks like this:

Parent, or root of the rig
1st Child – Automated task (ie., constraint to…, exposed as a slider)
2nd Child – Automated task (ie., sine wave script…, exposed as a slider)
Nth Child – Automated task (N…, exposed as a slider)
Last Child – Manual override (exposed to animator as a slider and/or view port control)

The last child will be exposed and animatable within parent space or local space.  All the automated tasks will move the visible child, and the animator will have the freedom to move it where ever it needs to be.  This can get very complex very quickly, and requires a fair amount of scripting/programming to automate the creation of the objects, the constraints, sliders, etc., and any interfacing related. You can see further examples of this in my article on Adaptive Rigging or in my demo reel archive. Also, see the great work of Bernard Haux or Eric Thivierge.

Mental Ray

Saturday, September 10th, 2011

Here’s is my reading for this evening.

my reading tonight

It’s a serious tome of knowledge.  I’ve been using mental ray since my first days with XSI 3.0.  I knew this book would help me transition to Maya, and further master my skills in mental ray for photo-realism.  Out of curiosity, and to save me time on my footnotes, I searched on amazon.com to see if there is a second edition.  There isn’t.  I did discover that people are selling this book for near 300$! I knew this book was a good source of information, but I understand now how coveted it must be at that price.  I’m glad I bought in 2009, for 37$, before the price hike.  I tend to buy books that interest me, even when I can’t read it immediately.  It’s a brilliant book.  It takes a lot of footnote taking, underlining, slow reading, and re-reading to understand and absorb the book.  I’ll take the author’s advice, and read through it first to gain an understanding of the topics, then use it a reference book.  Thus far, I’m happy to see the author and I have the same point of view,  “you must master the art of photography so you can bridge the gap between real-world photography and 3D.”  pg. xvii

Contemporary Sculpture 101

Thursday, September 1st, 2011

After organizing my lecture notes for class, I came across this short document I wrote on the fundamentals of sculpture, I called it Defining Strong Sculpture.  It was written after I had a lengthy conversation with one of my students on what it takes to create appealing sculpted forms, and how this applies to digital 3D modeling of characters, landscapes, and other objects.  I’d like to share these notes with you.  I outlined four fundamentals to consider when sculpting either physically or digitally; material selection or choice, interlocation, tension of space, and the texture or the language of the surface.

Material, form, and space define sculpture.  This is uniquely different from the planar 2D arts.  Form is to sculpture as shape is to the draw image.

When used in reference to sculpture, form is an elusive term.  It has been defined as the universal meaning of sculptural objects.  While this may be true, it is often much more.  It is shape, dimension, structure, technique, the intrinsic and extrinsic character, the arrangement of content, and all of these things in combination.  Further, and most important, it is the sculptor exercising his or her will on the piece and giving it life.†

Second is space.  Space would be the negative area surrounding the positive area of the form.  The marriage between form and space, how one “weaves” the two together, defines the appeal of the sculpture.  “The displacement of space by a new and intentional form by the artist creates a new reality: sculpture.” ¹  An excellent example of form displacing space in Brancusi’s Bird in Space.

Bird in Space, Brancusi

As a side note, this piece, as with all sculpture, cannot be fully appreciated or even understood from a single image online.  If you find a turn-around movie of the sculpture, please send me a link, and I’ll append this article.

Take this a bit further, what makes contemporary sculpture, today’s sculpture, unique from the other forms of art?  It can be argued that some paintings are very “thick”, and therefore protrude far enough to qualify as having form, and therefore are sculpture.  Or a ceramicist creates non-wheel thrown forms, and considers them sculptures.  I suppose from the traditional perspective this is absolutely true.  However, times have changed, and so have the mechanisms for the definition of sculpture.  Let’s look at welding, for example.  At the turn of the 20th century industrialism was sweeping across the first world, and this very practical method of fabrication changed the landscape of sculpture forever.  Sculpture was no longer limited with large bulky forms bound to the earth, but could penetrate space with linear wispy arms reaching into the sky.

David Smith

Look for work by David Smith for more examples of welding in art. The tensile strength of steel allowed artists to create armatures that are not columnar, but cantilevers in space.  Like a line draw on a wall, sculpture became drawing with steel in space.  Not only does the steel jut into space, but it can be covered or carry many sorts of materials at varying weights.  This leads me to the first step in defining an appealing sculpture, and what separates sculpture from it’s contemporaries.  Material choice, or the artist’s selection of materials.

Material choice and the juxtaposition of those materials is critical in defining the overall concept and appeal of the sculpture.  The painter chooses paint, the ceramicist chooses clay, photographers choose prints, yet the sculptor, unbound to a set material, chooses the material(s) that delivers the concept.  “At the present time, any and all materials are fair game for the sculptor”.²   The wrong material choice can lead the viewer astray, regardless of how well made, or how iconographic the piece may be.  The primary material juxtaposed with one or more materials is a critical fundamental step in creating appealing sculpture.  The overuse of juxtaposing materials can become confusing for the viewer, cluttered, and can lead the concept astray.  A balance, or proportional use of materials must be struck to avoid the viewer being mislead.

Second, is the interlocation, or interlocking of parts.  How do all the parts come together?  What fasteners, or lack there of, are used to join the materials?  A former professor of mine, Robert Booth, once referred to this concept as the “marriage of the parts”.  Interlocation can be achieved with a dove tail joint, a weld, a screw, a wooden nail, a nut and bolt, with glue, putty, cement, plaster, wire mesh, etc.  All of which are materials to be considered as a part of the whole, if not a part of the armature.  Interlocation could also be defined as the “arrangement of content”.³

Third, is to access the tension of the space, or the lack of tension.  Is the negative space used effectively to communicate the interlocation of the chosen materials?  Imagine two magnets of the same pole trying to touch, yet they are always just out of reach of each other.  That space is the balance from one material to the next.  The leaning steel forms of Richard Serra are great examples of the tension of space between subject and viewer, the viewer, I believe, being the juxtaposed material.

The fourth is the texture of the surface, the marking, or the language of the surface.  Manipulation of the material’s surface, affecting it intentionally, and juxtaposing the material against others is critical in designing the appeal of the piece.  The surface can not only create a narrative of the material, but can draw out the emotive reaction from the viewer, they may yearn to reach out and make contact with the piece.  Whether it is physical or digital, literal or perceived as literal, the tactile sense defines sculpture.

Eva Hesse

Affecting the surface, such as drawing on, painting, or burning it, will encourage the viewer to take a more intimate role of inspecting the piece.  This leads the sculptor to a arena of thinking, where they can have both the macro and micro visual stimulus at once.  Monumental sculpture, like a Richard Serra piece, combined with the intimacy of surface from an Eva Hesse piece.

Some may believe these ideas or instructions to be purely formal, and they may just be that.  But I won’t apologize for what I believe is a critical few steps to building strong sculpture, and that which makes a solid framework to deliver concepts.

 

The Sculptural Idea

Kelly, James J., The Sculptural Idea 4th Ed., 2004, Waveland Press Inc., pg. 83

¹   pg. 106

²   pg. 61

³   pg. 83

Real-time 3D in Flash

Monday, May 10th, 2010

Courtesy of the David Laser Scanner project there’s a way to do real-time 3d in Flash.  It’s called Mesh2Flash.  This tool was originally designed to showcase polygon meshes generated using the David Laser Scanner software, but I think this is great way to show off models made in any software.  All you need is the .obj or .dae format, and the Mesh2Flash.swf takes care of the rest.  You can find more information about Mesh2Flash here.

My biggest problem with this is that the .obj file must sit on the server with the Mesh2Flash.swf.  I’ve very little means to protect these objects from being stolen.  I tried password protecting the directory, but this only protected the directory.  With a direct link to the .obj file a person could read the file with a simple text editor, and take the object.  I think this is a dead end until I can find a means to secure my objects.  My objects are far too valuable to have hanging out on the server for someone to take and use or sell.  My understanding of the web is, “If you don’t want it stolen, then don’t put it on the web.”

Regardless of my fears, just imagine the possibilities of being able to pre-vis the 3d models a vendor might sell online.  What a fantastic way to “see” the mesh before purchasing it.   The Unity game engine would also be a viable way of showcasing real-time work in the browser, perhaps even more secure.

This model is not a scan, but is a primitive from XSI.  It’s was then triangulated, and exported as an “.obj” format for use with Mesh2Flash.

Click the image to launch the Mesh2Flash.

Example of Real-time 3d in Flash

Click and drag in the view to rotate it.
Arrow keys: Rotate view
+/-: Zoom in/out
Z/z: Zoom in/out
f/F: Decrease/increase camera focal length
s: Start/stop continuous rotation
a,r: Reset camera
q,e: Roll camera

Adaptive Rigging

Friday, April 16th, 2010

After a conversation with my student, Jake, I was reminded of some old research and experiments I did between April and July 2007.  I spent my summer off from teaching trying to recreate Bernard Haux’s excellent rigging work.  I don’t think my work was nearly as clean as Mr. Haux’s, but I was tapping into some good ideas for character freedom.  The traditional animators of Disney were free to draw and not be limited by the technology’s or the technical director’s limitations.  They could make marks on paper, over and over again.  Their two primary tools are the pencil and the paper.  Simple.  Of course, I’m oversimplifying the traditional animation methods, but it is clear they were not bogged down by lists of tools or the failed design of a rig.  One of the most challenging principles to include in a rigid 3d character is appeal; I’ll refer to appeal as the quality of the contour lines.  Another challenging principle to include is squash and stretch; both automatic and manual S & S controls.  In fact, most 3d I see floating around the web lacks this essential principle.  In fact, often the animator is blamed for the lack of principles.  Yet, it’s not necessarily the animator’s fault, and is most likely the rigger’s engineering of the character’s movement failed.  It took me years to realize I was leaving out squash, even though I had achieved stretch.  Sigh.

This rig design would adapt to the needs of the shot and scene.  Allowing an animator to stay true to the storyboard and character designs.  This gives tools for the animator to “free” the character from conventional methods of animating a rig.

In this concept demo I had a laundry list of options I was trying to achieve.  Again, inspired by Bernard Haux’s demos.  The arm had to have:  1. IK/FK switching for the whole arm,  2. Independent IK/FK blending for upper arm and lower arm,  3. Independent scaling of upper and lower arm,  4. Each node can be “torn away” from it’s parent,  5. Reshape the arm with a curve and objects along the curve,  6. A free elbow achieved by having IK enabled for both upper and lower arm ,  7.  Blend in standard corrective shapes,  8. Independent stretch for upper and lower arm.  9. Finally, Re-sculpt the mesh at any point during animation and key the sculpt.  Take a look.

Adaptive Rig Prototype

The most successful outcome from studying Mr. Haux’s work, which I didn’t originally intend, was my step into object oriented programming or OOP.  After creating my first successful “arm” rig I decided to automate the creation of this complex problem, so I could modify and recreate it without the need to repeat a list of steps in the software.  Unable to automate the entire rig due to time constraints I completed one facet of this problem.  That facet being the rig that runs along the curve.  The “back bone” of my rig.  Curve rigging has led me to some wonderful work, and has even changed the way I model.  Now it’s possible for me to draw any curve or curves, and apply a rig to the curve with the click of a button.  I build several features into this rig, and more recently have added sine wave auto-animation feature into it.  Probably the strongest feature is the built in squash and stretch based on the length of the curve, and based on the compression of the object along the curve.  Take a look at the curve auto-rig.

Rig From Curve

Programming the remaining rig setup was the next step, but I lost steam and time.  Why did I lose energy?  Well, I attended SIGGRAPH 2007 shortly after completing the demo reel.  While there I learned from a few Dreamworks and Lucas Arts riggers that Python is THE programming language of choice in the 3d entertainment industries.  That’s when I lost steam.  I was doing ALL of my programming in J-script.  Pfft.  (I discovered years later, after trying to find info on how to use OOP in J-script that it simply is impossible to have true OOP in J-script).   I stopped pushing this rig after running out of energy, and running out of time, and a new semester was about to begin.  Regardless, here’s my demo reel from July 2007.

Demo Reel 2007

My dream is to return to this problem, and complete it in both XSI and Maya.

My most recent use of the curve rig is in Red, the Ball with a Tail.  You’ll find superior squash and stretch with both the ball and the tail.