The first CAD-systems used by aerospace and automotive
enterprises from the mid-1960s, were 2D systems – an
electronic version of a drawing board.
Soon it became clear that design should be based on 3D
product models, whose 2D projections can be generated
However, simply adding a third coordinate to traditional 2D
graphics results in modeling only a wireframe, which is not
sufficient for calculating mass/volume characteristics of a
This led to the evolution of solid modeling
A simple solid model had its own limitations
It could not be easily manipulated or changed for
implementing design changes
Hence there was need to device a new method to allow the
designer to easily manipulate the model as desired by him
without loosing the design intent
Hence came the parametric modeling
WHAT IS PARAMETRIC MODELING?
The term parametric modeling denotes the use of parameters
to control the dimensions and shape of CAD models.
Parametric Design - a system that constructs relations among
the geometry of different elements. When one element is
changed, the geometry of the rest of the elements are
changed as well.
1. Dimensions can be linear and angular
2.Datums. Different CAD systems provide various types of
datums, but typically datum planes and datum coordinate
systems are provided. Datum lines and points are also
possible. Generally, datums are coordinate systems, or parts
of coordinate systems, that are used to control other
coordinate systems or geometric entities.
3. Constraints can be geometric or algebraic relationships that
the designer wants to impose on the geometry of CAD
a) Geometric constraints are parallel, perpendicular,
offset, tangent, and alignments.
b) Algebraic constraints are equations that the designer adds
to ensure that features sizes meet design requirements. For
example, a part cross section may have to be a certain area.
NEED OF PARAMETRIC MODELLING
• Convey a visual representation of the idea or concept.
• Create as many design concepts as possible.
• Evaluate the concept that best captures specified criteria and
2. BID AND PROPOSAL PROCESS-
• Minimize the time and costs required to create the bid geometry
• Submit models and geometry to support a proposed customer
• Accurately convey and communicate proposal requirements and
• Improve accuracy of the prop osal to meet budget and schedule
3. DIGITAL PROTOTYPING-
• Design, iterate, optimize, validate and visualize
products before they are built
• Rapidly create and explore design geometry
• Enable fast changes to legacy and heterogeneous
4. 2D DESIGN AND CONVERSION TO 3D-
• Support quick 2D concept design and the creation
of 2D engineering deliverables
• Accelerate the 2D-to-3D conversion process to
evolve 2D drawings into 3D models
5. REUSE LEGACY DATA-
Reuse and maintain legacy 2D & 3D data to
support current and future programsParametric
BENIFITS OF PARAMETRIC MODELING
3D modelling software can automatically update related parts of the
model when design changes are made and there is full bi-
directional associativity between parts, assemblies and drawings.
It captures and stores the design intent of the designer so that any
changes in the geometry will not affect the design intent for
which the part was designed
3D systems provide easier design revisions
Parametric modellers have a rollback feature that shows the
sequence in which the model was created
Adding design intent in the form of constraints between the model
elements and saving them in the file together with the model
simplifies future editing.
In parametric modeling, dimensions control the model.
Design intent is how your model will react when dimension
values are changed.
The drawing shows the intent of the
designer that the inclined plane
(chamfer) should have a flat area
measuring 2.5 inches and that it
should start at a point 1.25 inches
from the base of the drawing. These
parameters are what the designer
deemed significant for this model.
Remember that the placement of dimensions is very important because
they are being used to drive the shape of the geometry. If the 2.5 in.
vertical dimension increases, the 2.5 in. flat across the chamfer will be
maintained, but its angle will change.
In this drawing, what is important to the
designer is the vertical location and
horizontal dimension of the chamfer, rather
than the flat of the chamfer. 2.50
In the last drawing, the designer calls for a specific
angle for the chamfer. In this case the angle of the
chamfer should be dimensioned.
The true power of parametric modeling shines through when design changes need
to be made. The design modification is made by simply changing a dimension.
Since the counterbore is associated with the top surface of the ring, any changes in
the thickness of the ring would automatically be reflected on the counterbore
30Pattern: 8 Holes
To understand what is AUGMENTED REALITY first we need to see what is Virtual reality?
Virtual reality is using computer technology to create a simulated, three-dimensional world
that a user can manipulate and explore while feeling as if he were in that world.
Three-dimensional images that appear to be life-sized as seen by the user.
The ability to track a user's motions, particularly his head and eye movements, and
correspondingly adjust the images on the user's display to reflect the change in
An effective VR experience causes you to become unaware of your real surroundings and
focus on your existence inside the virtual environment.
DEFINITION : Augmented reality (AR) is a field of computer research which
deals with the combination of real-world and computer-generated data.
VR technologies completely immerse a user inside a synthetic environment. While
immersed, the user cannot see the real world around him.
In contrast, AR allows the user to see the real world, with virtual objects superimposed upon
or composited with the real world.
AR supplements reality, rather than completely replacing it. It creates the illusion that the
virtual and real objects coexisted in the same space.
Augmented reality adds graphics, sounds, haptic feedback and even smell to the natural
world as if it exists.
WHAT IS REAL AND WHAT IS NOT Real desk with virtual lamp and
two virtual chairs
(ECRC)Is this VR or AR?
AR enhances a user’s perception of interaction with the real world.
The virtual objects display information that the user cannot directly detect with his own
The information conveyed by the virtual objects helps a user perform real-world tasks.
AR is a specific example of what is known as Intelligence Amplification (IA): using the
computer as a tool to make a task easier for a human to perform.
Characteristics: Optical vs. Video
Optical see-through HMD
Video see-through HMD
AR can be accomplished using either optical HMD or video HMD
HMD:-HEAD MOUNT DISPLAY
Main classes of applications:
2. Manufacturing and repair
3. Annotation and visualization
4. Robot path planning
6. Military aircraft
The system can be used in pre-operative planning of a laparoscopic surgical
procedure in order to find both the right points to introduce the surgical
instruments and the best path to reach the organ concerned in the surgical
A very handy tool for instructors and faculty members for subjects involving
Head Up Guidance System
(Flight Dynamics Inc.)
Boeing 737 cockpit with Head-
up Display (HUD)
(Flight Dynamics Inc.)
Nightvision system in the 2000 Cadillac DeVille
APPLICATIONS: NIGHT VISION