Software configuration and data base For engineering students CAD CAM

1. by
Mr. Siddesh Kumar N M
Assistant Professor
Department of Mechanical Engg.
P. E. S. College of Engineering
Mandya, Karnataka, India.
Dept. of Mechanical Engineering, PESCE. 1
CAD/CAM
P18ME551
15-Oct-20

2. The software configuration of a graphic system
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3. Introduction
Graphics software is the collection of programs written to make it convenient for a user to
operate the computer graphics system
It includes Programs to generate images on the CRT screen.
To accomplish various types of interaction between the user and the system.
The graphics software for a particular computer graphics system is very much a function of
the type of hardware used in the system.
The software must be written specifically for the type of CRT and the types of input devices
used in the system.
The differences between a storage tube and a refresh tube would also influence the
graphics software
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4. Newman
and
Sprouls
lists 6
ground
rules for
designing
graphic
software
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Simplicity :
Graphic software
should be very
easy to use
Consistency:
Graphic software
should be
predictable way
to the user
Completeness:
Graphic software
should provide
the complete
information
Robustness: it
should be
tolerant of minor
misuse of the
operator
Performance:
within limitation
by system
hardware the
system response
much be very fast
Economy: It
should not be too
expensive and
memory
occupying

5. The software
configuration
of a graphic
system
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In the operation of the
graphics system by the user, a
variety of activities take place,
which can be divided into
three categories:
• Interact with the graphics terminal to
create and alter images on the screen
• Construct a model of something
physical out of the images on the
screen. The models are sometimes
called application models.
• Enter the model into computer
memory and/or secondary storage

6. The
graphic
software
can be
divided
into
three
modules
According to a conceptual model suggested by Foley
and Van Dam:
1. The graphics package
2. The application program
3. The application data base
Dept. of Mechanical Engineering, PESCE, Karnataka 6

7. Graphics
package
15-Oct-20 Dept. of Mechanical Engineering, PESCE, Karnataka 7
It is the software support between the user and the
graphics terminal
It manages the graphical interaction between the
user and the system
It also serves as the interface between the user and
the application software.
The graphics package consists of input subroutines
and output subroutines.
The input routines :accept input commands and data
from the user and forward them to the application
program.
The output subroutines: control the display terminal
and convert the application models into two-
dimensional or three-dimensional graphical pictures.

8. Application
Program
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The central module is the application program.
It controls the storage of data into and retrieves data out
of the application data base.
The application program is implemented by the user to
construct the model of a physical entity whose image is
to be viewed on the graphics-screen
Application programs are written for particular problem
areas.
Problem areas in engineering design would include
architecture, construction, mechanical components,
electronics, chemical engineering, and aerospace
engineering.

9. Data
base
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The data base contains mathematical,
numerical, and logical definitions of the
application models, such as electronic
circuits, mechanical components,
automobile bodies, and so forth.
It also includes alphanumeric
information associated with the models,
such as bills of materials, mass
properties, and other data.
The contents of the data base can be
readily displayed on the CRT or plotted
out in hard-copy form.

10. Functions
of a
graphic
package
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These functions can be grouped
into function sets.
Each set accomplishes a certain
kind of interaction between the
user and the system. Some of the
common function sets are:
• Generation of graphic
• Transformations
• Display Control and windowing functions
• Segmenting functions
• User input functions

11. Generation of
graphic element
• Graphic element is a basic
image entity such as dot (or
point), line segment , circle
etc.
• The collection of element in
the system could also
include alphanumeric
characters and special
symbols
• Special hardware to speedup
the process of generating
the element
• The term primitive is used in
reference to graphic element
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12. • Primitive is a three-
dimensional graphic
construction
• Such as sphere , cube or
cylinder
• In three-dimensional
wireframe models and
solid modeling primitives
are used as building
blocks
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Generation of
graphic element

13. Transformations
• Transformations are used to
change the image on the
display screen and to
reposition the items in the
data base
• The transformation includes
 Enlargement of the
image
 Reduction of the image
 Repositioning of the
image
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14. Display control and
windowing
functions
• The functions provides
the display screen at
different screens at the
desired magnifications
• It make uses different
transformation to display
the models
• Hidden lines removal
• In some systems the user
must modify or remove
the hidden lines but in
some software is more
sophisticated to remove
the hidden lines
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15. Segmental function
• Segmental functions
provides user with the
capability to selective
replace, delete or modify
portions of the image
• The term segment refers to
portion of the image which
must be modified
• Storage tube CRT is not
suitable for segmentation
function where it will erase
the complete image
• Raster scan is well suited
for segmentation function
the screen is redrawn 30 or
more times in a second
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16. User input
function
• It is the important set of
functions because they
permit the operator to
enter the command
• Input functions are
specifically written for a
particular compliment of
input devices
• Input functions should be
written to maximize the
benefits of the interactive
feature
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17. Thank you
Dept. of Mechanical Engineering, PESCE, Karnataka 15-Oct-20 17