Week 3

Question 1

what is the split and merge algorithm?

Answer 1

a recursive algorithm to extract line segments from points

Question 2

what is the input of the split in a split merge algorithm?

Answer 2

A list of points

Question 3

what is the output of the split in a split merge algorithm?

Answer 3

List of segments (pair of points)

Question 4

what is the parameters of the split in a split merge algorithm?

Answer 4

Threshold distance

Question 5

what is the input of the merge in a split merge algorithm?

Answer 5

List of segments (pair of points)

Question 6

what is the output of the merge in a split merge algorithm?

Answer 6

List of segments (pair of points)

Question 7

what are the parameters of the merge in a split merge algorithm?

Answer 7

Threshold angle

Question 8

what type of sensor is a camera

Answer 8

a passive sensor that captures light reflected from objects

Question 9

what does a camera measure?

Answer 9

angles

Question 10

what type of information does a camera provide?

Answer 10

2D information of a 3D world

Question 11

how can a 360 degree view be obtained from a camera?

Answer 11

by adding mirrors

Question 12

what are the pros of cameras?

Answer 12

-Cheap and small
-lots of information
-well-known and commonly used
-Libraries with algorithms (OpenCV)

Question 13

what are the cons of cameras?

Answer 13

-Lots of data
-require calibration
-lighting and colour consistency

Question 14

what is a pixel?

Answer 14

a picture element is the smallest element of an image

Question 15

how are greyscale images represented?

Answer 15

by 2D arrays of pixel values (0 = black, 255 = white)

Question 16

what is computer vision?

Answer 16

a field of artificial intelligence (AI) enabling computers to derive information from images, videos and other inputs

Question 17

when is computer vision used for images?

Answer 17

when we are only interested in parts of an image it can be used to identify objects and find relations

Question 18

what is Odometry?

Answer 18

the use of data from motion sensors to estimate change in position over time

Question 19

where is Odometry used?

Answer 19

in passive sensors that measure the velocity of a robot’s wheels

Question 20

what are the pros of odometry?

Answer 20

-included in many motors
-provides position information
-can be combined with laser (ICP)

Question 21

what are the cons of odometry?

Answer 21

-errors grow (systematic)
-dependency on accelerations, weight distribution, floor type…
-heading direction ‘lost’ after a few metres

Question 22

what is a kinect 3D camera?

Answer 22

-RGB camera, infrared camera and infrared laser emitter
-provides 3D distance information
-range of 0.5-5 meters

Question 23

what are the pros of a kinect 3D camera?

Answer 23

-cheap
-allows 3D reconstruction of a scene
-high resolution
-Point Cloud Library (PCL) to process the data

Question 24

what are the cons of a Kinect 3D camera?

Answer 24

-indoor use only
-lots of data (computation)