1' dia

1
Budapest Tech John von Neumann Faculty of
Informatics Institute of Intelligent Engineering
Systems
Introduction to virtual engineering
Lecture 4. Construction of shape in the model
space
László Horváth WWW.nik.hu
2
CONTENTS
Contextual modeling of structures of
shapes Constructive solid geometry Modification
of an initial shape by form features About
building of topology Main groups of form features
3
Contextual modeling of structures of shapes
Visualization
Associative characteristics
Visualization of bodies
Scene
Solids
Relationships of solids
Animation
Projection
Combination
Placing
Rendering
Position, scale
Modification
Movements
Volume
Shape
Surface characte-ristics
Form feature
Analysis of solids
Hair, particle
Volumetric
Texture
Bended sheet
Simulations
Geometry
Conditioning
Local characteristics
Collisions
Surface
Movements
Contour
4
Constructive solid geometry
Intersection
Difference
Primitives
Union
A - B
B - A
A, B
A - B
5
Modification of initial shape by form features
Volume subtracting shape modification
Creation of body by tabulation
Form feature
Modified shape
Base feature
6
Extended topology of boundary
7
Building topology using Euler operators
MEV make edge and vertex!
MEF make edge and face!
KEMR kill edge and make ring (closed chain of
edges)!
8
Start building of topology
Edge removal and vertex merging operations result
a model that consists of single edge and single
polygon.
9
Main groups of form features
1. Defined by type, volume adding and volume
subtracting Cuboids, cylinder, sphere, cone, and
torus. 2. Contour based, volume adding and
volume subtracting Tabulated (extruded),
revolved, pyramid, tube, swept, and lofted. 3.
Transformed, added and volume subtracted
volume. Constructive solid geometry in shape
modification 4. Modification of shape by surface
Building separately created surface. 5. Form
features for conditioning existing form features
(dress-up features) Fillet, chamfer, shell, and
draft.
10
Contour based form features
11
Connecting surface and solid
12
Intersection of solid by surface (sewing)
13
Conditioning (dress-up) form features
Chamfer
Fillet
Shell
Draft
14
Fillet form features
Constant radius
Radius changing according to a law
Linearly changing radius
Defined by boundary curve
curve (law)
spine
Filleting with automatic removal of topological
entities
Corner fillet
15
Draft form features
p
p
p
p
E
n
E
n
F
F
F
d
d
d
F
pl
pl
d
,
Extrapolated fillet surface
Outside neutral edge
16
Opening solid at surfaces to create shell
17
Irregular model construction bended and cut
sheets
Bend panel
Fitted edges
Bend
Form feature
It is not a bend!