67,149 research outputs found
Universal attraction force-inspired freeform surface modeling for 3D sketching
This paper presents a novel freeform surface modeling method to construct a freeform surface from 3D sketch. The approach is inspired by Newtonâs universal attraction force law to construct a surface model from rough boundary curves and unorganized interior characteristic curves which may cross the boundary curves or not.
Based on these unorganized curves, an initial surface can be obtained for conceptual design and it can be improved later in a commercial package. The approach has been tested with examples and it is capable of dealing with unorganized design curves for surface modeling
A simple construction method for sequentially tidying up 2D online freehand sketches
This paper presents a novel constructive approach to sequentially tidying up 2D online freehand sketches for further 3D interpretation in a conceptual design system. Upon receiving a sketch stroke, the system first identifies it as a 2D primitive and then automatically infers its 2D geometric constraints related to previous 2D geometry (if any). Based on recognized 2D constraints, the identified geometry will be modified accordingly to meet its constraints. The modification is realized in one or two sequent geometric constructions in consistence with its degrees of freedom. This method can produce 2D configurations without iterative procedures to solve constraint equations. It is simple and easy to use for a real-time application. Several examples are tested and discussed
Sketch-based virtual human modelling and animation
Animated virtual humans created by skilled artists play a remarkable role in todayâs public entertainment. However, ordinary users are still treated as audiences due to the lack of appropriate expertise, equipment, and computer skills. We developed a new method and a novel sketching interface, which enable anyone who can draw to âsketch-outâ 3D virtual humans and animation.
We devised a âStick FigureFleshing-outSkin Mappingâ graphical pipeline, which decomposes the complexity of figure drawing and considerably boosts the modelling and animation efficiency. We developed a gesture-based method for 3D pose reconstruction from 2D stick figure drawings. We investigated a âCreative Model-based Methodâ, which performs a human perception process to transfer usersâ 2D freehand sketches into 3D human bodies of various body sizes, shapes and fat distributions. Our current system supports character animation in various forms including articulated figure animation, 3D mesh model animation, and 2D contour/NPR animation with personalised drawing styles. Moreover, this interface also supports sketch-based crowd animation and 2D storyboarding of 3D multiple character interactions. A preliminary user study was conducted to support the overall system design. Our system has been formally tested by various users on Tablet PC. After minimal training, even a beginner can create vivid virtual humans and animate them within minutes
Sketching-out virtual humans: From 2d storyboarding to immediate 3d character animation
Virtual beings are playing a remarkable role in todayâs public entertainment, while ordinary users are still treated as audiences due to the lack of appropriate expertise, equipment, and computer skills. In this paper, we present a fast and intuitive storyboarding interface, which enables users to sketch-out 3D virtual humans, 2D/3D animations, and character intercommunication. We devised an intuitive âstick figurefleshing-outskin mappingâ graphical animation pipeline, which realises the whole process of key framing, 3D pose reconstruction, virtual human modelling, motion path/timing control, and the final animation synthesis by almost pure 2D sketching. A âcreative model-based methodâ is developed, which emulates a human perception process, to generate the 3D human bodies of variational sizes, shapes, and fat distributions. Meanwhile, our current system also supports the sketch-based crowd animation and the storyboarding of the 3D multiple character intercommunication. This system has been formally tested by various users on Tablet PC. After minimal training, even a beginner can create vivid virtual humans and animate them within minutes
Sketching-out virtual humans: A smart interface for human modelling and animation
In this paper, we present a fast and intuitive interface for sketching out
3D virtual humans and animation. The user draws stick figure key frames first and
chooses one for âfleshing-outâ with freehand body contours. The system
automatically constructs a plausible 3D skin surface from the rendered figure, and
maps it onto the posed stick figures to produce the 3D character animation. A
âcreative model-based methodâ is developed, which performs a human perception
process to generate 3D human bodies of various body sizes, shapes and fat
distributions. In this approach, an anatomical 3D generic model has been created with
three distinct layers: skeleton, fat tissue, and skin. It can be transformed sequentially
through rigid morphing, fatness morphing, and surface fitting to match the original
2D sketch. An auto-beautification function is also offered to regularise the 3D
asymmetrical bodies from usersâ imperfect figure sketches. Our current system
delivers character animation in various forms, including articulated figure animation,
3D mesh model animation, 2D contour figure animation, and even 2D NPR animation
with personalised drawing styles. The system has been formally tested by various
users on Tablet PC. After minimal training, even a beginner can create vivid virtual
humans and animate them within minutes
Coulomb Distortion Effects for Electron or Positron Induced Reactions in the Quasielastic Region
In response to recent experimental studies we investigate Coulomb distortion
effects on reactions from medium and heavy nuclei for the case of
electrons and positrons. We extend our previously reported full DWBA treatment
of Coulomb distortions to the case of positrons for the
reaction in the quasielastic region for a particular nuclear model. In
addition, we use previously reported successful approaches to treating Coulomb
corrections in an approximate way to calculate the Coulomb distortion effects
for reactions for both electrons and positrons for the case of a
simple nuclear model for quasielastic knock-out of nucleons. With these results
in hand we develop a simple {\em ad-hoc} approximation for use in analyzing
experiments, and discuss methods of extracting the ``longitudinal structure
function" which enters into evaluation of the Coulomb sum rule. These
techniques are generally valid for lepton induced reactions on nuclei with
momentum transfers greater than approximately 300 .Comment: 18 pages, 6 figure
Studies in a transonic rotor aerodynamics and noise facility
The design, construction and testing of a transonic rotor aerodynamics and noise facility was undertaken, using a rotating arm blade element support technique. This approach provides a research capability intermediate between that of a stationary element in a moving flow and that of a complete rotating blade system, and permits the acoustic properties of blade tip elements to be studied in isolation. This approach is an inexpensive means of obtaining data at high subsonic and transonic tip speeds on the effect of variations in tip geometry. The facility may be suitable for research on broad band noise and discrete noise in addition to high-speed noise. Initial tests were conducted over the Mach number range 0.3 to 0.93 and confirmed the adequacy of the acoustic treatment used in the facility to avoid reflection from the enclosure
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