By Mritunjay Kumar
Course Content
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
Surface modeling overview
Surface modeling process
Basic Surface modeling functions
Case study for Basic functions
Advance Surface modeling Functions
Case study for Advanced functions
Create complex surfaces using proper techniques
Case study for surfacing techniques
Repair imported data by IDD function
Case study for IDD functions
Create Surfaces from Scan data
Case study for scan modeling
a) Surface modeling overview
• Introduction of surfaces and shapes
• Nurbs/Bezier Curves and surfaces
Introduction of Surfaces
• A surface is a two-dimensional, topological manifold. The most familiar
examples are those that arise as the boundaries of solid objects in
ordinary three-dimensional Euclidean space R3 — for example, Shapes
like Sphere, cylinder and flat surfaces are coming together and form
free form surface and those are complex quilts in pro/e language
• Surface modelling is different technique to create complex shapes
which are not possible by solid modelling tools and sometimes we need
to create different uneven shapes to fulfil design requirement and there
are different kind of shapes are creating one surface quilt
Reference: www.en.wikipedia.org
Introduction of Shapes
Simple shapes can be described by basic geometry objects such as a
•
•
•
Set of two or more points
Line, Curve, Plane, Square, Circle, Cube or Sphere.
Concave or Convex type
Most shapes occurring in the physical world are complex and those are two
types Non rigid and Rigid.
Reference:
1. www.en.wikipedia.org
2. www.carbodydesign.com
Surfaces and shapes
Reference: www.carbodydesign.com
Surfaces and Shapes
Example of a rim part global modification. The constraint is on the upper boundary
(G0+G1+G2 fixed). The handle is the lower curve (translated).
Rim part before deformation
Rim part after deformation
Tangent and Curvature continuity between two surfaces are playing important role into
surface modeling to achieve require shapes
Reference: www.carbodydesign.com
Nurbs and Bezier
• Nurbs: Non-uniform rational basis spline (NURBS) is a mathematical model
commonly used in computer graphics for generating and representing curves
and surfaces. It offers great flexibility and precision for handling both analytic
(surfaces defined by common mathematical formulae) and modeled shapes
• Bezier: Bezier surfaces are a species of mathematical spline used in
computer graphics, computer-aided design, and finite element modeling. Bezier
surface is defined by a set of control points. Similar to interpolation in many
respects, a key difference is that the surface does not, in general, pass through
the central control points; rather, it is "stretched" toward them as though each
were an attractive force.
Reference: www.en.wikipedia.org
Difference between Nurbs and Bezier
Nurbs Surface
• Complex area possible by single
surface
• Less flexibility as patches are
connected
• Control points are always connected
directly to the curve/surface
• NURBS evolve into two parametric
directions, called s and t or u and v.
Single Nurbs surface
Bezier Surface
• Complex area possible by patch
subsets
• More flexibility for individual
Nurbs surface divided
patches
into subsets called
• Control points are not connected
to
Bezier
each other
• Bezier evolve into only one
parametric direction, usually called
S or u
Reference: www.en.wikipedia.org
Difference between Nurbs and Bezier
Bezier Surfaces
Nurbs Surfaces
Bezier Surfaces
Nurbs Surfaces
Reference:
1. www.google.com
2 www.en.wikipedia.org
b) Surface modeling process
• Surface modeling process
• Difference between surface and solid modeling
Surface modeling process steps
Create datum
features in model
which represents
main skeleton
Plan feature
sequences based on
shell or closed type
part
Create surface
patches using
curves and sketch
entity
Merge all surfaces
to each other and
create single quilt
Define draft to all
surfaces w.r.t die
direction
Complex shapes can
be achieved by
Boundary blend and
other functions
Create rounds on
edges at last before
thickening part
Add holes and
cutout features on
thicken or solid part
Assign material and
other parameters to
part
Surface modeling process for 2D
sketch
User's 2D
concept sketch
3D template
model
After aligning
the template
with the sketch
user draws
directly on the
sketch.
Final shape
obtained after
modifying the
template and
adding new
feature edges
Final solid model
after surface
creation and
Modification
Overview of Surface modeling process
Reference: www.carbodydesign.com
Template alignment
User draws an
approximate
bounding box on the
sketch and marks its
eight corners
Default conjuration
of the template is an
orthographic side
view
the corners of the template bounding box would exactly
match the red dots marked by the user
Reference: www.carbodydesign.com
Back
Modification of a 2D curve
Original curve and the
modifier strokes.
New shape of the target curve.
The original curve is shown
dashed for reference.
Reference: www.carbodydesign.com
Back
Initial Surface Model
Initial boundary
loop consisting of
four curves
Edge swapping
Preliminary
triangulation using a
vertex created at
the centroid
Final result after
face splitting
and mesh
smoothing using Vspring method
Reference: www.carbodydesign.com
Back
Surface modification
Initial surface model
Concavity applied to
surface keeping
the boundary vertices
fixed
Modification of seat
base by manipulating
control point structure
Reference: www.carbodydesign.com
Back
Example of Surface modeling process
Input Sketch
Design in progress
Initial Template
Final Template
Triangular mesh
near the headlight
Surface Model
Reference: www.carbodydesign.com
Surface and solid modeling
Surfaces and solids are the underlying math that defines the geometry of
the forms you create. There are three ways to define 3D geometry: solids,
surfaces and wireframes.
Wireframes don’t play much of a role in CAD, but primarily in digital
content creation (DCC) and gaming. The easiest way to understand the
difference between surface and solids modeling is to think of a water
balloon; the water in the balloon would be solids modeling, while the latex
skin would be surface modeling.
Reference: http://fireuser.com
Difference between surface and solid modeling
Solid Modeling
Solid modeling is
defining
an object
with
Solids
modeling
programs
Features
such
as
extrudes,
geometric
mass
usually
create
models
by
It
was
originally
developed
extrude
cuts,
revolves,
creating
a base
solidand
andis
for
machine
design,
radii,
chamfers,
etc.
adding
or subtracting
from
used heavily
for engineering
Examples
of
solids
modeling
it
with
subsequent
features
with
large
part
assemblies,
programs are Solidworks,
digital testing
and rapid
CATIA,
and ProEngineer
prototyping
Surface Modeling
Surface modeling is defining an
Skin
is created
bywith
lofts,
sweeps,
object’s
exterior
andefined
The surfaces
are either
by
and
NURBS
curves
i.e.
sculptured
infinitesimally
thin
It wasor
developed
forskin
the
aerospace
poles
guide curves.
A surface
is
surfaces
with
lots
of
curvature
and automotive
industries
in the
considered
a solid
only when
it is
late 70s. Rhinoceros
Alias
completely
enclosed.3D
It and
is used
to
Studiotechnical
Tools are surfaces
examples(e.g.
of aair
make
surface
modeling
programs
plane
wing)
or aesthetic
surfaces
(e.g. car’s hood).
Reference: www.fireuser.com
c) Basic Surface modeling functions
• Basic surface modeling functions
• Editing, Merging functions
Basic surface modeling
functions
Creating
Extrude surfaces
Change mode from solid
to surface
Select sketching
Plane
Create sketch and assign
depth
Basic surface modeling
Creatingfunctions
Revolve surfaces
Change mode from solid
to surface
Select sketching
Plane
Create sketch then define
rotation axis and angle
Basic surface modeling functions
Creating Fill surfaces
Select existing sketch or
create a new
Select sketching
Plane
Create a sketch
Basic surface modeling
functions
Creating
Sweep surfaces
Select mode from solid
to surface
Pause for sketch menu to
create trajectory
Create trajectory and define
start point
Create a sketch
Select on icon to
start sketch
Basic surface modeling
functions
Creating
Blend surfaces
Select mode (Sketch or
Selected)
Section 1
Insert section 1
You can define normal condition with
Plane at both side sections
Section 2
Insert section 2 and define
offset value
Surface editing and Merging functions
Trimming surface by extrude option
Surface trim by
thicken
Surface mode
Surface trim by
extrude
Surface editing and Merging functions
Extending surfaces
Click here to
extend surface
Select surface edges
Different
options to
extend surface
Surface editing and Merging functions
Trimming and merging operations
Open trimming_merging.prt
Different options will be
performed during training
Input
Output
d) Case study for basic functions
• Case study will perform during training session using basic
surface modeling functions.
e) Advanced surface modeling functions
• Create datum curve using different functions
• Advanced surface modeling functions
Datum curve functions
Creating curve through points
Spline curve passing through
all points
Select datum point feature
from model tree
Different techniques will
perform during training session
Datum curve functions
Creating blend curve
Select end point 1
Select end point 2
Tangent condition at
end point 1
Differed techniques will perform
Tangent condition at
during
training session
end point
2
Advanced Surface Modeling
Functions
Creating Surfaces
by Swept blend
Click here
Section 1
Select Trajectory
Menu for trajectory,
Sections and edge
continuity
Section 2
Insert section 2
Advanced Surface Modeling
Functions
Creating Surfaces
by Boundary blend
1st direction
2nd direction
Define tangent
continuity
Select Curve 1
Select Curve 2
Selection for 1st
direction
Input
Define tangent
continuity
Output
Advanced surface modeling
functions
Creating Sweep surfaces
with multiple trajectories
Click here to
select multiple
trajectory
Trajectory
selection menu
Chain 1Chain 3
Chain 2 Origin
Enter sketch
mode
Input
Output
Advanced Surface Modeling
Functions
Creating Surfaces
by N sided blend
Open N-sided_patch.prt
Select all edges together
then click on Done
Click on N-sided surf
Input
Output
Advanced Surface Modeling
Functions
Creating surface
by Graph feature
Open part
graph_sweep.prt
Select trajectory
Create graph
feature
Sketch a geometry
Create sweep surface Define relation in
Sketch should sketcher
contain mode
coordinate system
Advanced Surface Modeling
Functions
Using trajpar with
sweep surface features
Open trajpar.prt
Create sketch
Select trajectory to
create sweep feature
SD3 denotes circle
diameter
Enter relations120 is mean
Sketch circle
diameter
Trajpar varies
Magnitude
is 10
35
Cycles
from 0 to 1
f) Case study for advanced functions
Input
Output
Exercise will performed during training session
Reference: www.e-cognition.net
g) Create complex surfaces using proper techniques
• Working with 3D curves and Surfaces
• Geometry Analysis functions
Datum curve functions
Creating offset curve
Select edge
Offset by variable
Variable dimension
value 160
Variable dimension
value 380
Differed techniques will perform
during training session
Working with 3D curves and surfaces
Input
Output
Refer next slide to proceed further
Create a new
part in Creo
Import case_study2.igs
D
A
Name assign to surfaces for
identification
Repeat same
process for
surface B
Click on Surface A to create
untrimmed surface
Click on Surfaces > Surface free
form to create untrimmed
surface
Next level activities to be perform during training session
C
E
B
Working with Draft and B-side design
Input
Output
Activity will perform during training session
Geometry analysis functions
Curvature using sections
Curvature section tool can
analyze curvature along
sections for selected
surfaces. reference, System
creates a series of
porcupine
Geometry analysis functions
Offset Surface or Curve
Offset surface analysis can create a surface mesh at an
adjustable offset value from the selected surfaces. This is
useful to check overlapping of the surface mesh reveals
locations which could cause problems when thickening part
Geometry analysis functions
Analyze draft angle
Select surfaces or
solid geometry
Select pulling
direction
Enter draft angle
If draft value is 3 then flanges
may have different color
h) Case study for surfacing techniques
Create 3D surfaces and thicken part
Input
Output
Surface modeling by master model technique
The Master Model technique is a style of surface modeling with topdown-design methodology. Master modeling technique is used to design
products that use multiple interlocking body components to form an
enclosure with an overall styled shape.
Input
Output
i) Repair imported data by IDD function
•
•
Redefining & Deleting Imported Geometry
Heal & Collapse Geometry
Import data doctor tool overview
Import data doctor(IDD) tool can repair imported geometry. Gaps
between surfaces and tangent continuity defined by IDD. Following are
the common errors which can be found in imported geometry
•
•
•
•
•
•
•
•
•
•
•
Bad surfaces (concave domain or boundaries with parallel)
Bad two-sided edges
Bad wireframe curves
Poorly tessellated edges
Short one-sided edges (warning)
Bad vertices (warning)
Unsatisfied wireframe
Unsatisfied tangency
Gaps not added to wireframe
Non tangent edges
Small surfaces
Imported geometry process flow
Import iges or other
type surface data in
Creo
If any open gaps and
errors found then
repair it by Import
data doctor
Study surface model
and plan next
activity
Create surfaces by
extrude, sweep or
boundary blend
option
Create sketch, points
or curves to start
surface modeling
operations
Create free form
surface using
Surface free form
option
Trim/cut surfaces by
extrude, trim or
extend option
Merge overlapping
surfaces by Merge
Intersect option
Solidify or thicken
surface to get final
model
j) Case study for IDD functions
Input
Surfaces is not
tangent continuous
Open area need to fill
Open area need to fill
Output
Create a new
part in Creo
Click to enter for IDD
editing environment
Click to enter for IDD
editing environment
Training
session
activity
k) Create surfaces from scan data
• Create 3D surfaces from Scan data
• Trace sketch from JPEG or Tiff
Create 3D model from scan data
Import scan data file
in Creo or Wildfire
Check part location
w.r.t top level
assembly
If not placed
properly then move
it to correct location
Create datum curve
by X-sec option
Create datum planes
and X-sec passing
through scan data
Verify scan quality
and study part
shape and boundary
Create sketch and
3D curves using Xsec curve and Scan
data
Create surfaces from
curves and build
features
Check deviation
between scan and
surface data
Trace sketch from JPEG or Tiff images
Input
Output
Reference: www.learnsolidworks.com
Create a new
part in Creo
Click to add images
Use different functions from Images
menu to adjust its position
Select plane to place Image
Select Image Deodrant1.jpg and
Repeat same activity to import
Deodrant2.jpg
Activity will perform during training session
l) Perform scan modeling exercise
Create a new
part in Creo
Import faceted data
casestudy_l.stl
Activity
performed
during training
session
Thank You