L1: Introduction to Surveying

Question 1

Why is surveying important (how is it used)?

Answer 1

1) map of the Earth
2) prepare navigational charts
3) establish property boundaries (of private and public lands)

less important:
4) develop data banks of land-use and natural resource info (help manage the environment)
5) determine facts on size, shape, gravity, magnetic fields of Earth
6) prepare charts of moon and planets

Question 2

Define surveying (in general)

Answer 2

The art and science of taking field measurements on the surface of the Earth

Question 3

Define surveying (in the engineering context)

Answer 3

The process of measuring lengths, heights, and angles on site; either for the preparation of large-scale plans or in order that engineering works can be located in their correct positions on the ground

Question 4

Define geomatics

Answer 4

The modern discipline which integrates the tasks of gathering, storing, processing, modeling, analyzing, and delivering spatially references or location information

(including the computerization and digitalization of data collection, processing, and analysis)

Question 5

What do geomatics engineers do?

Answer 5

Design, develop, and operate systems for collecting and analyzing spatial information about the land, the oceans, natural resources, and manmade features

Question 6

Define remote sensing

Answer 6

The acquisition of information about an object without making physical contact with the object

Question 7

What is the difference between an active sensor and a passive sensor in remote sensing?

Answer 7

Passive sensors: use electromagnetic waves from an external source (such as the sun)

Active sensors: produce and use their own waves

Question 8

What are two different satellite orbits (briefly describe each)?

Answer 8

Geostationary: satellite stays over the same point on the surface through its orbit

Quasi polar: satellite loops around the poles to cover the entirety of Earth’s surface

Question 9

What is orthophotography and how does it apply to airborne surveying?

Answer 9

In some airborne surveys, photos are taken from a plane

These photos will be deformed due to the perspective of the camera

Through orthophotography, an accurate picture can be found from combining photos from multiple perspectives

Question 10

Define GIS

Answer 10

A computer system for capturing, storing, checking, and displaying data related to positions on Earth’s surface

Question 11

What are the four main functions of GIS?

Answer 11

1) Data management for storing geographic locations
2) Visualizing geographic data (typically using maps)
3) Analyzing spatial relationships and patterns using geoprocessing
4) Creating new data or editing existing data

Question 12

Define geodesy

Answer 12

The science of measuring and understanding Earth’s geometric shape, orientation shape and gravitational field

Question 13

What are the three models of the Earth’s shape in order of increasing accuracy?

Answer 13

Least accurate: spheroid
Ellipsoid
Most accurate: geoid

Question 14

Define geoid

Answer 14

The equipotential surface that most closely approximates to mean sea level in the open oceans

Question 15

Why are all map projections inaccurate?

Answer 15

It is impossible to accurately represent a geoid (or even a spheroid for that matter) on a 2D surface

Question 16

What is the difference between a geodetic and plane survey?

Answer 16

Geodetic surveys take into account Earth’s curvature (preforming calculations on an ellipsoid)

Plane surveys do not consider Earth’s curvature (performing calculations as if Earth were flat)

Question 17

List the six main types of surveying (briefly defining each)

Answer 17

GEODETIC: covering such large areas that Earth’s curvature must be accounted for

TOPOGRAPHICAL: establish the position and shape of natural and man-made features over a given area (usually for cartography or GIS)

PHOTOGRAMMETRY: using photographs with special cameras on aircraft (in pairs, they produce 3D images of ground features)

HYDROGRAPHIC: gather info on marine environment (map coastlines and sea bed for navigational charts)

CADASTRAL: establish and record boundaries and ownership of land and property

ENGINEERING: any survey work carried out in connection with the construction of civil engineering

Question 18

What are the survey field measurements and the instruments often used to perform each?

Answer 18

1) Horizontal and slope distances (tapes, electronic instruments)

2) Vertical distances / heights (levels)

3) Horizontal and vertical angles (theodolites)

Question 19

Define control surveying

Answer 19

Surveying that is used to establish highly precise positions and elevations to be used as references for other surveys

You obtain a network of points with highly precise position and elevation

Question 20

Define detail surveying

Answer 20

Surveying that is used to determine and locate the features and improvements on a section of land

Question 21

What is the difference between a passive control mark and an active control mark? Which one is more advantageous and why?

Answer 21

Passive control marks are controls that are physical objects (such as a metal disk or rod) that cannot alert of movement; once their coordinates are measured once, they are not recalibrated for many years; they are often disturbed, damaged, or destroyed over time

Active control marks have receivers that are constantly collecting and updating information on how they have moved, making them accurate even over time; furthermore, you can use an active control mark from afar, making them more convenient

Overall, active control marks are more advantageous

Question 22

What is the coordinate system used for surveying?

Answer 22

Cartesian

A plane rectangular system using two axes at right angles

One axis is N, other is E

Scale along both axes is always the same

Take an arbitrary origin at the extreme SW of the surveyed area (no negative values)

Question 23

What are the four types of north (briefly defining each)?

Answer 23

True north: a fixed point on Earth (the accurate determination of which is only used for special construction projects and not normally in engineering surveys)

Magnetic north: north as determined by a freely suspended magnetic needle; changes with time and place (only used in low-order surveys or to give a general indication of north)

Arbitrary north: any convenient direction chosen to represent north even if it isn’t true or magnetic north (the most commonly used north in engineering surveys)

Grid north: the direction of north based on the National Grid

Question 24

Define whole circle bearing (WCB)

Answer 24

The angle measured clockwise from N to a line

Same thing as azimuth

Question 25

Define scale

Answer 25

The ratio of horizontal and/or vertical plan distances to horizontal and/or vertical ground distances

Question 26

How many square meters in a hectare?

Answer 26

10⁴

Question 27

How many sq.ft in an acre?

Answer 27

43 560

Question 28

What are the three systems used for angles (briefly describe each and include the measurement of a full circle)?

Answer 28

Sexagesimal: degrees, minutes, seconds; 1 degree = 60 minutes; 1 minute = 60 seconds; circle = 360 degrees

Centesimal: gons (with prefixes); 1 gon = 100 cgon; 1cgon = 10 mgon; 1 circle = 400 gons

Radians: radians…; 1 circle = 2*pi radians

Question 29

Why are field notes important?

Answer 29

They contain measurements, sketches, descriptions, and many other items of information (taken by hand or digitally)

They are the only permanent records of the work

Question 30

What are the important qualities of handwritten field notes?

Answer 30

Accuracy
Integrity
Legibility
Arrangement
Clarity

Question 31

What are the three main types of notes kept in practice?

Answer 31

sketches
tabulations
descriptions