TAPESTRY: The Art of Representation and Abstraction
Data Attributes
What's it all about?
Throughout history men and women have been interested in classifying similar objects, animals, and events. The sciences all search for the most elemental truths, from which other facts can be derived.Computer programs, to some extent, turn this search around. The programmer gets to decide what the universe if made out of, what the elements are. He or she gets to decide how they can be combined, what relationships they can have to each other, etc. The user then explores the universe of creations made possible by these basic building blocks.
One of the obvious ways to gain "representational range" (i.e., to expand the range of possible shapes which the program can be used to create) is to associate varying qualities with the basic geometrical shapes. These varying qualities are called attributes. Most of them will be familiar from your experience of the physical world, since the qualities (e.g, "color", "transparency", etc.) are taken from the classification schemes we use to describe the world.
Possible Attributes
Remember, the particular attributes that a program makes available will very likely be different from these. However, these do represent some of the qualities that the program is likely to use in rendering your geometry, so the information has to come from somewhere. Sometimes the attribute is a built-in constant, sometimes it is is an attribute of the layer or object group, and sometimes it is an attribute of the geometrical objects themselves.- Color
- Transparency
- Surface smoothing (a rendering effect)
- Shadow casting (or receiving)
- Index of refraction
- Object material density
- Object Name
- Layer, line weight, etc.
- Visibility (display), snapability, etc.
Not all of these attributes are compatible, and most are tied to the visual character of the surface, so they are also related to the rendering algorithm with which the program is equipped (index of refraction only makes sense to a ray-tracing program, for example).
Object Attribute v. Layer Attribute v. Global Attribute?
You don't really want to set the color of every polygon in a complex model. It might be better to have the polygons share an attribute (like "Layer") and associate the color with the attribute. Similarly, you might want shadows in some renderings, but not others. Turning them on or off for the entire rendering ("globally") would be preferable to a layer-based approach. Be alert to where in the hierarchy of your model you can control particular attributes, and how.
Last updated: April, 2014
