CG Modeling 3: Advanced - An Introduction to Computer Graphics for Artists - page 277

It is possible to edit sculpt geometry at the geometry component level, but the
sculpting tools provided in the application are adequate for most operations.
Because of the focus on traditional tools, it is easy to forget while using a sculpt
program that vertices are being edited. Instead, it feels like working with real clay
and carving tools. An artist rarely has to think about their work at the level of
geometry components.

15.4.3 Application

Digital sculpting is used to create complex characters and complicated detail on
non-character objects. It is not an appropriate tool for objects that can be defi ned
more simply and accurately using NURBS or subdivision surfaces. For example, a
subdivision surface might make an excellent character base mesh, but a digital
sculpting tool would be used to create detailed normal maps. After these have been
applied, the subdivision object would be converted to polygons, the sculpted normal
maps would be transferred, and the polygonal character would be rendered with
animation that was originally applied to the subdivision surface model.

15.5 Procedural Modeling

15.5.1 Introduction

Procedural modeling relies on a node-based architecture to defi ne how a model
is built. Instead of giving an artist a group of tools that are used to carve, sculpt,
or stitch the shapes of a model together, the artist creates tools to grow a model
based on a variety of inputs. The power of procedural modeling is that it is capa-
ble of executing repetitive modeling tasks much more quickly than an artist
(Fig. 15.5 ).
Procedural tools have been in use in many industries for several decades. For
example, architects use them to design buildings by making tools that understand
local building codes and other limitations. The way this might work in practice is
that a procedural based architecture design application would automatically add the
right number of elevators based on building height or the right number of lavatories
based on fl oor area. The advantage to working like this is that architects have less to
worry about during the design process, and important aspects of their projects can
be managed by the software.
In the fi lm industry, procedural systems have been used to generate VFX.
Fireworks, water, rain, fur, crumbling buildings, and cars that crumple correctly are
all examples of the kind of VFX procedural tools have been used for in the past.
These are not models however, but effects. In these examples, procedural tools