survey Flashcards
chain types and lenghts
20m/30m Metric chain
66 feet (100 link) Gunters chain
100 feet Engineers chain
33 feet (16 link) Revenue chain
sag correction in chain survey
W^2 L /(24P^2)
limitng length of offset error allowed on paper
- 025 cm
difference between bowdich method and transit method of closing error correction
Bowditch method - angles and lengths are of equal precision
Transit method - Angular measurement more precise
probable errors of given weights and deviations
for single measurement of unit weight e = 0.6745 *σn-1 for error in most probable value ep = e / sqrt(ΣW) for error in single value of weight W ew = e / sqrt(W)
Plum point
Perspective point
principal point
in areal photograply
Plum point: A point where the vertical through the optical centre meets the photograph.
Perspective point: A point where the rays from the objects converge.
principal point: A point where the perpendicular from the optical centre of the lens meets the photograph
Horizontal stave / subtense bar in techometric survey
Horizontal stave, also known as subtense bar, used for measuring both the horizontal as well as vertical distance in place where chaining is impossible
Spire test in used for adjustment of ?
Spire test in used for adjustment of horizontal axis.
Classification based on the nature of field survey
- Land survey
- Marine or hydrographic survey
- Astronomical survey
Classification based on object of survey
- Engineering survey
- Military survey
- Mine survey
- Geological survey
- Archeological survey
Classification on instrument used
- Chain survey
- Theodolite survey
- Traverse survey
- Triangulation
- Tacheometric survey
- Plane table
Vernal equinox?
Vernal equinox, two moments in the year when the Sun is exactly above the Equator and day and night are of equal length; also, either of the two points in the sky where the ecliptic (the Sun’s annual pathway) and the celestial equator intersect.
Sensible horizon?
Sensible horizon at a point on earth surface is a circle in which a plane passing through a point of observation and tangential to the earth’s surface intersects the celestial horizon.
prismatic compass and surveyor compass
prismatic small size readings in W.C.B simultaneous reading and sighting tripod not essential graduation inverted graduations on needle body
surveyor compass bigger circular box 150 mm dia quadrantal bearing first sighted then reading tripod is essential graduations are erect and separate from needle
telescope normal and telescope inverted
normal = when vertical side is on left
and vice versa
swinging of telescope
transiting of telescope
revolving in horizontal plane
revolving in vertical plane 180 degree
temporary adjustments of theodolite
setting centering leveling focusing of eye piece focusing the objective
radiation method
it is suitable when area to the surveyed is small and all the required station are clearly visible and accessible from instrument station
resection method
it is employed when plane table occupies a position not yet plotted on the drawing sheet. it is commonly used for establishing instrument station
two point and three point problem
intersection method
it is used when the base station are visible and accessible but the other stations are only visible not accessible. it is most suitable for hilly area and also known as graphical triangulation
traversing method
generally used when a narrow strip of terrain is to be surveyed. ex-survey of road, railway etc. used for both open and close traverse
plane table surveying types
https://theconstructor.org/surveying/plane-table-surveying-methods-examples/12877/
clinometer
pantagraph
tellurometer
ghat tracer
clinometer =angle measuring instrument
pantagraph = plan enlarging instrument
tellurometer = microwave measurement, EDM
ghat tracer = gradient finding instrument
farthometer
instrument used for measuring depth in ocean
