Exam 2020

Question 1

Mention three different aspects that has to be included in an assembly model (in e.g. a CAD
system)

Answer 1

An assembly model needs to include
 Hierarchical relations
o assembly -> sub-assembly -> part
 Mating conditions
o geometrical restrictions, etc
 Mechanical degrees of freedom

Question 2

Bézier and B-spline are two types of curves used in geometry modeling. What are the
advantages of B-spline curves?

Answer 2

Better local control of the curve
 Order of the polynomial does not increase with the number of control points
 Easier to define joined curve segments

Question 3

Describe what LOD (Level of Detail) is and how it can be used to increase the performance
of a visual simulation.

Answer 3

Many representations with different precision is stored. Depending on the distance to the object, one
suitable representation is shown, i.e. when an object is far away a simple representation is shown.
When an object is very far away it might not even be drawn at all.

TÄNK DATORSPEL SAMT PILTAVLA

Question 4

What are the six most central functions of a PLM system?

Answer 4

The most central functions of PLM systems are:
 Item (part, assembly, component) management
 Product structure management
 Document management
 Change management
 Retrieval of information
 Workflow and distribution management

Question 5

On a higher level, a PLM system have two major tasks. One is to manage information, what
is the other? Give some examples of tools used for the second task.

Answer 5

Create Information, e.g. with CAD systems or simulation software.

Question 6

What are homogenous coordinates and why are they used in computer graphics?

Answer 6

Homogenous coordinates are created by adding an extra coordinate, w, to the Cartesian
coordinates: ][][ wzyxPzyxP homogencartes  normally (in computer graphics) w = 1.
They are used in order to simplify the calculation of transformations. With homogenous coordinates
all transformations can be calculated as the same matrix multiplication which can be optimized for
speed in the graphics processor

Question 7

What is the benefits of using virtual geometry assurance?

Answer 7

Minimizing the need for costly physical prototypes
 Finding problems as early as possible in the development process (easier and cheaper to fix)
 Faster development process with efficient tools (time to market)
 Increased quality

Question 8

How can Rd &T be used in some task in the geometry development process?

Answer 8

Analyze different assembly concepts
 Analyze and define robust locating systems
 Simulate and verify the final demands
 Virtual matching for trimming the production process