UNIVERSITY OF JAFFNA

FACULTY OF ENGINEERING
MP 7010 : Production Engineering

Assignment -1

MUKUNTHAN T. 2017/E/069

1. a. What are the disadvantages of a graphics program written directly with the device driver
commands?

 Complexity: Writing a programme directly with device driver commands can be

extremely difficult and time-consuming, as it requires in-depth knowledge of the
underlying hardware and how it interacts with the operating system. This can make it
challenging for programmers to create and maintain the application.

 Portability: Programs written directly with device driver commands are not portable
across operating systems or hardware platforms because they are tightly coupled to
the specific device driver and hardware. This can make it challenging to run the
programme on multiple systems without significant modification.

 Dependence on hardware: Programs written directly with device driver commands

are reliant on the hardware and device driver in use. This indicates that if the
hardware or device driver is modified, the programme will likely need to be modified
to continue functioning.

 Maintenance: It can be difficult to maintain and update programmes written directly

with device driver commands as new operating systems and hardware are released.
Due to the close connection between the programme and the device driver, updates
to the driver have the potential to break the programme, necessitating extensive
rework.

 Performance: Programs written directly with device driver commands may be less
effective than those using an abstraction layer such as DirectX or OpenGL. By
simplifying the code to be executed on the hardware, an abstraction layer enables a
programme to make more efficient use of the hardware's resources and run faster as
a result.

 Security: Programs written directly with device driver commands may contain
additional security vulnerabilities due to their direct access to hardware resources and
ability to execute with elevated permissions. In other words, an attacker could
potentially gain access to sensitive system resources if the programme contains a
security flaw.
b. In describing the shape of an object, what is the main reason for using the object’s model
coordinate system?

The primary justification for utilising the model coordinate system of an item to describe its
form is that it offers a consistent and fixed reference frame for describing the geometry of the
object.

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c. Briefly describe the procedure by which the coordinate of a point on an object, measured
with respect to the model coordinate system, are converted to the virtual screen device
coordinates (u, v).
 The first step involves transforming the coordinates of the location from the model
coordinate system to the world coordinate system. This is often accomplished by
performing a sequence of transformations to the point's coordinates, such as rotation,
translation, and scaling.

 After converting the point's coordinates to the world coordinate system, the following
step is to convert them to the view coordinate system. Typically, this is accomplished by
applying a view transformation, such as a camera or viewpoint transformation, which
represents the position and orientation of the virtual camera in the real world.

 Next, the coordinates of the point are transformed from the view coordinate system to
the projection coordinate system. Typically, this is accomplished by employing a
projection transformation, such as a perspective or orthographic projection, which
represents the mapping from 3D space to a 2D virtual screen.

 Finally, the coordinates of the point are transformed from projection coordinates to
screen coordinates. This is typically accomplished through the application of a viewport
transformation, which maps the point's coordinates from the virtual screen to the physical
screen, taking into account the screen's resolution, aspect ratio, and device-specific
characteristics.

 Each preceding step requires a matrix operation, as transform matrices are typically
represented by matrices.

 Once the preceding steps have been completed, the point's final coordinates (u, v) will be
in screen space and can be used to draw the object on the screen.
d. There are two coordinate systems X1Y1Z1 and X2Y2Z2, where Z2 is opposite of Y1, X2 parallel
with Z1, and Y2 is opposite of X1. The origin O2 when measured in X1Y1Z1 is (5, 5, 0). The X1Y1Z1
coordinates of point P is (2, 0, 3).

(a) By visual judgment, obtain the X2Y2Z2 coordinates of P.

2
 𝑋2 3
P’= [ 𝑌2 ] = [3]
𝑍2 5

(b) With respect to X1Y1Z1, using the standard Rotx(), Roty(), Rotz(), and Trans(a,b,c)
to derive the transformation T* that will transform the rigid body of X2Y2Z2 to coincide
with X1Y1Z1.
Trans (0,5,5)
cos(90) 0 sin(90) cos(−90) − sin(−90) 0
Roty (90). Rotz (-90) = [ 0 1 0 ] ∙ [ sin(−90) cos(−90) 0]
−sin(90) 0 cos(90) 0 0 1

0 0 1 0 1 0
= [ 0 1 0] . [−1 0 0]
−1 0 0 0 0 1
0 0 1
= [−1 0 0]
0 −1 0
T* is
T*= [ (1 0 1 0), (-1 0 0 5), (0 -1 0 5), (0 0 0 1)] T

(c) Calculate P* = T* • [2 0 3 1]T.

P* = T* • [2 0 3 1] T
= [ (1 0 1 0), (-1 0 0 5), (0 -1 0 5), (0 0 0 1)] T • [2 0 3 1] T
= [2,3,5,1] T

(d) Verify that P* identifies with the coordinates obtained in (a).

P’=P* and Identical

(e) Is T* the T12 or T21 ?

T12

2. a. Explain why geometric data exchange is important.

 Important when using multiple CAD software

 Data translation between systems becomes required
 Crucial for data exchange between suppliers
 Data is stored in various ways
 All CAD systems have their own database formats, which are often proprietary and
frequently private.
b. You need to submit all the created files during the exercises b, c & g. Also the screen capture
of the model from SolidWorks & other CAD package.
Model one of the below shapes (based on your index number in the table)in SolidWorks and
save native part file:

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 2017/E/069
Cube
r=15mm
SLDPRT

c. Create following files from the above model:

- IGES
- STEP AP203
- STEP AP214
- VRML
- STL
- 3D XML
- DXF

4
IGES

STEP AP203

STEP AP214

5
VRML

6
STL

3D XML

DXF

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d Explain different sections of IGES file.
 This part includes information about the file, including the version of IGES used, the date
the file was generated, and the author's name.
 Global Section: This section specifies file-wide settings, such as the units used for
measurements.
 Directory Entry Part: This section identifies the entities that comprise the model, such as
points, lines, and surfaces, and provides information on where to get the data for each
object.
 This part includes the information for each entity specified in the Directory Entry
Section.
 Terminate Section: This section marks the conclusion of an IGES file.
e. Find and explain the differences of STEP AP203 & STEP AP214 files.
AP203 is the previous version of the STEP standard, which was designed to facilitate the
interchange of product manufacturing information (PMI) across various CAD systems. It only
covers two-dimensional and three-dimensional geometric representations.
AP214, commonly referred to as "Automotive Design and Manufacturing," enhances the
capabilities of AP203 to incorporate more complex geometric representations, such as free-
form surfaces and advanced brep (boundary representation), as well as a larger range of PMI
data. In addition, it contains features such as assembly representations and external
references.

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f. Discuss the advantages of below file formats:
VRML:
 VRML is an open standard, which means it is freely available for anyone to use and can be
read by many different software programs.
 VRML allows for the creation of interactive 3D models, meaning users can interact with
the model by moving around it, zooming in and out, and performing other actions.
 VRML allows for animation, which means that objects within a scene can be made to move
or change over time.
 VRML has built-in support for lighting and shading, which can be used to create realistic-
looking models and scenes.

3D XML:
 3D XML is a proprietary format developed by Dassault Systemes for its CATIA,
SOLIDWORKS and ENOVIA software.
 It is a compressed format that can be very efficient for large files
 3D XML is optimized for real-time rendering in 3D applications, which means that models
and scenes can be viewed and interacted with quickly and smoothly.
 3D XML is designed to be easily integrated with other tools and systems, such as PLM
(Product Lifecycle Management) software and other manufacturing tools.
 3D XML can be used to create detailed models and assemblies with a lot of components,
and It also contains rich meta data that can be used in downstream process

g. Open the DXF file from another CAD package and save it as the native file format. Identify
whether there are any data loses during the data share via DXF file.