Cineversity Wiki

Skinning

2012-02-22T05:48:41+00:00

Skinning is the process of binding the character rig to the polygon mesh to be driven. The process starts with the association of the joints to drive the deformations of the mesh vertices. Unfortunately, the process doesn’t stop there. Typically, you will need to adjust the amount of energy imparted to each mesh vertex from the driving joint’s influence. This is done via weight painting.

Category:Glossary
Category:Rigging

Revision Control System or RCS

2012-02-15T02:46:31+00:00

A Revision Control System (RCS) is a database library originally intended to manage source code, but applying towards assets to be created and managed for computer animation pipelines. Even small operations can benefit from the use of an RCS; such usage does add some overhead to tasks, but the cost is minor compared to the benefits. Ever found yourself digging for the proper texture map after a full day at 1:AM with a looming deadline—and pick the wrong one? Yeah. No amount of Red Bull can get you over that one. Instead, an RCS is there to help insure that only the proper assets are approved and used. Of course, like anything else, everyone on the team must follow the established team rules, and correctly utilize the RCS, otherwise, it all falls apart.

Asset Management

2012-02-15T02:40:24+00:00

Asset Management refers to the tracking, updating, and approval of assets to be used in the production of CG animation or visual effects. Not limited to just the production business, of course, asset management is an essential part of any workflow. In some cases, this is handled directly by the artists, though in most professional and semi-pro teams, this is accomplished with a combination of special code or an application designed for such use. Asset management apps have been expensive in the past, and often are restrictive compared to the needs of the team. One solution has been to use MySQL (an open source database) and write and track with Javascript and/or Python.

Other shops use Revision Control Systems to handle the work, as conceptually, the workflow of an RCS is very similar to the needs of an animation team. RCS systems use library analogies to “check-in,” “check-out,” track changes, and so on. Systems like Source Safem, originally developed to manage source code for computer programming, is such an example, though by no means the only one.

Pipeline

2012-02-14T23:05:02+00:00

The Pipeline is a term that describes the application and file interchange backbone of your production workflow. Small shops usually have a very informal pipeline, managed by the same people who create content elements and assets. Larger shops have staff dedicated to the pipeline, as it is the single most vital component of a smooth CG production. Without a strong, reliable pipeline, you will experience delays, data loss, and worse. Even with a pipeline and a dedicated staff, you may still experience these issues. Fortunately, a dedicated staff gives producers someone else to blame, and sheilding you from such an unfortunate position.

There are various aspects of the production pipeline, just as there are several aspects of CG production. Asset management is one of the mostr critical aspects of the pipeline, in addition to the traditional information technology-related functions (as in, keeping everyone operating smoothly, data backed up, and so on). Another aspect is the facilitation of the rendering pipeline, often separate from the overall pipeline to insure rendering reliability.) The pipeline often requires scripts written in Python to facilitate automated functions; glue code (translations) for inter-application communications; code to drive compositing node trees on the fly; loading and unloading of compute and disc resources; rendering control; and so on. Feature film pipelines are by far the most complex you are likely to encounter.

If you are lucky enough to have dedicated staff for pipeline support, thank them. By them coffee or a danish. Give them a car. Whatever it takes, theirs is a high-pressure position, and good pipeline management staff are worth their weight in gold. Without them, nothing can happen.

Mesh

2012-02-14T22:51:28+00:00

A Mesh is another term for the net of geometric polygons that make up the objects in your scene. Meshes reference, or are referenced by attribute tags such as surfacing and UV information, animation rigs, simulation and rendering engines. Without meshes, you would have only parametric objects to render. Meshes are formed by vertices and the faces that are created from a minimum of three vertices (triangles). Edges bridge the connection between two or more vertices. You should avoid free-standing vertices, edges or polygons in your mesh, unless said elements are intended to serve a specific purpose.

You may have seen other terms used instead of “mesh” but the other terms all apply to the basically the same definition.

OBJ Format

2012-02-14T22:42:43+00:00

The OBJ Format is one of the earliest mesh interchange formats. Created by the developers of Wavefront, which led eventually to Maya, the OBJ format is fairly simple, supporting polygons and UV data. An external material file can be created that is referenced by the OBJ file for some surfacing information. For mesh-only interchange, the OBJ format is adequate. In some cases, OBJ may be the only way to get data to interchange between certain applications, as was the case with Pixologic’s Z Brush until the debut of Go-Z. There are better formats today that transfer higher order surfaces, and will likely be a better choice. As always, test first!

UV Coordinates

2012-02-14T22:38:12+00:00

UV Coordinates refers to the coordinate space used by meshes and image-based textures to be applied to the mesh surfaces. Specifically, UV coorinates are nothing more than a different label from the XY coordinates that you are familiar with. They are labeled differently as to not be confused by the XY coordinate label, as XY refers to geometry/world space, and UV refers to image space. These two spaces can share similar information, but since they refer to vastly different outcomes more often than not, it makes sense to keep them separate, and refer to them separately.

Historically, UV coordinates have been a necessary evil (though they are also a powerful tool). In the last few years, the Disney company has developed the PTEX coordinate space, which helps to remove the burden of UV complexity from less technically-inclined users. That said, It will take some iterations of various products for PTEX to be integrated into the various applications that are necessary; in addition, tools like Body Paint have made working with UVs as easy as possible, and offers tremendous control and opportunities to problem solve, since the UVs are directly accessible. The PTEX format produces images that appear as a jumble, which is very disorienting if one has experience with applications such as Body Paint.

STL Format

2012-02-14T22:33:14+00:00

The STL format is a mesh interchange format that was originally intended to send computer models to a 3D printer so that the computer model could be made into a physical object. This format is a triangles-only format. No higher level surface types are allowed, so whenever you save an object mesh into this format, make sure you understand what you are getting as a result of the translation. Most computer animation and modeling programs, as well as many CAD programs, support the STL format.

Note: in order to have a successful 3D printout from the STL format (or more correctly, meshes that are interchanged with the format), the model must be clean and well-built. It must be “watertight,” in that there are no “leaks” or errant holes within the mesh (make sure you weld your vertices). There should be no disconnected vertex, edge or face data, lest those elements cause the printing process to fail. There are several good, free utilities online that can check the validity of STL files, and their suitability for 3D printing.

Category:Integration

2012-02-14T22:27:40+00:00

Integration is a term used to describe the interchange of mesh data, image data, and forms of meta-data between applications within a content creation pipeline. Integration is an important aspect of your workflow; you will not be using just one application from one vendor in this process. You may already be familiar with different interchange formats such as OBJ or STL mesh formats; interchange is part of the integration process. Other formats, such as FBX, will transport mesh data, motion data, UVs, cameras, lights and so on. As versatile as it it, FBX is not a complete scene description (as all of the content creation applications utilize custom forms of data, or have aspects to them, that cannot be directly converted from one application to another.) Why mention this here? Simple: to illustrate that integration is not perfect. Vendors do their best to facilitate interchange between applications, but the process can only be taken so far. The terms in this category define some of the common terms that you are likely to encounter when you deal with interchange or integration of applications in your pipeline.

FBX Format

2012-02-14T22:27:15+00:00

The FBX Format is an interchange format originally created by FilmBox, which eventually become Motion Builder, and was purchased by Autodesk, via their acquisition of Alias several years ago. Originally intended as a way to get motion data from FilmBox to other content creation applications, the format has now become a defacto interchange format among all 3D content creation applications. The interchange offered by FBX support is extensive, but far from perfect; many aspects of each vendor’s offerings are proprietary, and do not translate directly (if at all.)

FBX has shown to be good for:

mesh data (models)
animation data (baked; rigging information does not translate due to differences in spatial references and internal data structures)
UV coordinates
Some shading information
joint placement
light information
camera information

It is always wise to run a series of tests with live data (but backed up for safety) in order to determine the efficacy of the format, and interapplication support for the elements you need to interchange. In most cases, special scripting support may be required to translate additonal information into your pipeline.