key definitions - ES

Question 1

engineering surveying

Answer 1

a collection/ record of data relevant to site and/ or project

Question 2

geomatics

Answer 2

the science and study of spatially related information

Question 3

hydrographic surveying

Answer 3

a sub-element of geomatics

science and study of underwater features e.g, mapping coastlines and seabeds

Question 4

photogrammetry

Answer 4

a sub-element of geomatics

science of acquiring measurements and data from aerial photographs e.g. topography, distances, angles etc.

Question 5

remote sensing

Answer 5

a sub-element of geomatics

using EM energy to interact with matter to study geological formations, mineral deposits, climate change etc.

Question 6

cartography and visualisation

Answer 6

a sub-element of geomatics

accurate scaled maps of a site - conventional surveying - now combined with 3d visualisation technology

Question 7

GIS - geographic information systems

Answer 7

a sub-element of geomatics

developing the software and hardware require to process and gather relevant data

Question 8

engineering surveying

Answer 8

a sub-element of geomatics

any survey work in conjunction with construction

Question 9

polar co ordinates

Answer 9

form: r and theta
r = distance from known point to P
theta = angle between “initial line” and OP

Question 10

rectangular co ordinates

Answer 10

x and y co ordinates

Question 11

OS

Answer 11

Ordnance survey - standard maps widely used in surveying

Question 12

GNSS

Answer 12

Global navigation satellite system - geo-positioning location system

Question 13

plane of collimation

Answer 13

plane parallel/ containing the line of sight

Question 14

datum

Answer 14

reference level/ point

Question 15

reduced level

Answer 15

height of a point relative to a chosen datum

Question 16

TBMs

Answer 16

Temporary/ Transferred Bench Marks - set on stable ground area of site

Question 17

OSBMs

Answer 17

Ordnance Survey Benchmarks - reduced levels above an ordnance survey datum e.g. sea level

Question 18

parallax

Answer 18

observed displacement of an object caused by the change in observer’s point of view

Question 19

change point - leveling

Answer 19

where the instrument is moved in between the fore sight and back sight reading

Question 20

angle measured against z axis

Answer 20

zenith angle

Question 21

vertical axis - angles

Answer 21

directly perpenducular to line through the target

Question 22

trunnion axis

Answer 22

perpendicular to vertical axis (line of sight)

Question 23

line of collimation axis

Answer 23

through the line of vision through the total station

Question 24

detail surveying

Answer 24

process of adding features to a control network to provide graphical representation

Question 25

selective vs non-selective surveying

Answer 25

choosing which points to survey working from initial control points images recorded from per-established control points

Question 26

setting out

Answer 26

"reverse surveying" immediately prior to site construction

Question 27

primary and secondary controls (give examples)

Answer 27

accurate benchmarks and datum references from control network vs baselines, offsets and grids derived from the primary controls

Question 28

MBMs

Answer 28

Master Benchmarks

Question 29

low divergence lasers

Answer 29

fine cross-section lasers which don't split off/ diverge at long distances

Question 30

LASER

Answer 30

Light Amplification (for) Stimulated Emissions Radiation

Question 31

sub-parallels

Answer 31

the lines 180km (parallel rings) either side of the central meridian which have the projection scale factor of 1

Question 32

space segment - composition

Answer 32

6 orbits at 55° incline 3.9km/s orbit speed

Question 33

control segment - composition

Answer 33

contains the MCS - master control system where all information is relayed and processed e.g. accuracy offset

Question 34

Kepler's first law

Answer 34

the area swept by any planet across a specific time period is always the same as another (in elliptical orbits)

Question 35

Newton's law of gravity/ attraction

Answer 35

F(attractive) ∝ Mm or ∝ 1/D D = separation

Question 35

low dilution of precision

Answer 35

many satellites observed at high elevations to preserve accuracy and reliability

Question 36

ionosphere and troposphere

Answer 36

50-1000km and 0-10km

Question 37

left hand angle

Answer 37

mean forward circle reading minus mean back circle reading

Question 38

pseudo range (GPS)

Answer 38

time taken for satellite signal to reach reciever

Question 39

multi-path

Answer 39

error caused by a signal reflecting off a nearby surface