Unit 6. Control Surveys

Question 1

are used to establish coordinate systems for mapping.

Answer 1

Control surveys

Question 2

are used to establish baselines from which field surveys can be performed.

Answer 2

Control surveys

Question 3

___ for a mapping survey is provided by two or more points on the ground, permanently or semi-permanently monumented, and precisely fixed in position horizontally by distance and direction or coordinates.

Answer 3

Horizontal control

Question 4

It is the basis for locating map features.

Answer 4

Horizontal control

Question 5

can be established by the traditional ground surveying methods of traversing, triangulation, or trilateration, or by using GNSS surveys.

Answer 5

Horizontal control

Question 6

For large areas, a sparse network of horizontal (and vertical) control can be densified using ___.

Answer 6

photogrammetry

Question 7

For small areas, horizontal control for mapping surveys is generally established by ___.

Answer 7

traversing

Question 8

Horizontal control methods (5)

Answer 8

• GPS
• Photogrammetry
• Traversing
• Triangulation
• Trilateration

Question 9

A series of horizontal distances and directions are observed to connect points whose positions are to be determined.

Answer 9

Traversing

Question 10

When a large area is to be surveyed and where the methods of traversing would not be expected to maintain a uniform high accuracy over the entire area.

Answer 10

Triangulation

Question 11

___ consist of networks of geometric figures with almost all of the angles measured directly in the field and with relatively few of the sides measured.

Answer 11

Triangulation surveys

Question 12

The lengths of the sides of a series of triangles are measured and the angles are computed from the lengths.

Answer 12

Trilateration

Question 13

This is the most accurate method of establishing horizontal control.

Answer 13

Trilateration

Question 14

the vertices of the triangles in a triangulation system

Answer 14

Triangulation stations

Question 15

one of the lines in a triangulation system whose length is precisely measured and its direction determined; usually located at the beginning of the system

Answer 15

Base line

Question 16

one of the lines, usually at regular intervals, whose length is precisely measured and serves as a check for length calculations

Answer 16

Check base

Question 17

Consists of a network of connected triangles which adjoin or overlap each other.

Answer 17

Triangulation Systems

Question 18

Triangulation Systems. Four of the commonly used types are:

Answer 18

Chain of Single Triangles
Chain of Quadrilaterals
Chain of polygons
Chain of polygons with an extra diagonal

Question 19

Choice of figure (2)

Answer 19

Equilateral triangles
Squares

Question 20

is provided by benchmarks in or near the tract to be surveyed and becomes the foundation for correctly portraying relief on a topographic map.

Answer 20

Vertical control

Question 21

is usually established by running lines of differential levels starting from and closing on established benchmarks.

Answer 21

Vertical control

Question 22

Vertical control methods (5)

Answer 22

Differential leveling
Trigonometric leveling
Barometric leveling
GPS
Photogrammetric methods

Question 23

the sum of the angles about each station is equal to 360 degrees

Answer 23

STATION ADJUSTMENT

Question 24

the sum of the interior angles of each triangle equal to 180 degrees

Answer 24

FIGURE ADJUSTMENT

Question 25

The term “___” is applied to a function used to determine the strongest route through a chain of triangulation figures composed of quadrilaterals and central-point polygons.

Answer 25

strength of figure

Question 26

The ___ determines the manner in which angular errors affect the computed lengths and positions.

Answer 26

shape of the figures