Point-based modeling, animation and rendering of dynamic objects
Bart Adams |
Contact: Bart Adams
Ph.D. Thesis, Katholieke Universiteit Leuven, 205 + xiii p
Abstract
Dynamic objects are becoming ubiquitous in computer graphics applications.
Algorithms, often based on physical laws, are proposed to alter
the shape and appearance of virtual 3D objects.
The visual richness of the resulting computer generated images
has to match with the increasing demand for more and more realism.
In this dissertation we assess a recent trend to resort to point primitives
for the representation of such dynamic 3D objects
and propose techniques to optimally exploit the characteristics
of these point primitives in a wide range of computer graphics applications.
It is shown how the absence of explicit connectivity information
between the point samples significantly facilitates the handling of dynamically changing objects.
Based on customized data structures and resampling operators, efficient
algorithms are proposed for point-based modeling, animation and rendering of
dynamic objects.
In the first part of this thesis, geometric modeling algorithms are
proposed to interactively alter the shape and appearance of point-sampled
3D surfaces. Building on efficient point data structures, we show how
boolean operations such as the union and intersection
of complex surfaces can be computed at interactive rates.
A 3D painting application is proposed entirely centered around the
use of point primitives. It allows painting arbitrary levels of detail on
point-sampled surfaces using virtual 3D brushes. Local resampling
operators are given to maintain an adequate sampling density
during the whole modeling process.
The second part of this work uses point primitives for physics-based
modeling of dynamic objects. Next to point sampling the object's
surface, a point-sampled volume representation is used to efficiently
solve the equations governing the dynamic behavior. By decoupling the
volume and surface representation, a trade-off can be made between
visual complexity and physical accuracy. We show how the use of point
primitives leads to efficient algorithms for the simulation of elastic
solids and viscous fluids and propose dynamic point sampling operators
to handle brittle and ductile fracturing.
The last part of this dissertation discusses ray tracing algorithms
for point set surfaces. Spatial and temporal coherence is exploited
to efficiently visualize dynamically changing point surfaces.
Sharp features, such as the ones obtained by boolean operations and
fracture animation, are faithfully reproduced using the concept of
surface clipping relations.
The discussed rendering algorithm is illustrated on various
examples generated with the point-based animation framework introduced earlier
in this dissertation.
All presented techniques contribute to the increasing requirement
to efficiently handle dynamically changing objects in computer
graphics applications.