GATE Civil Engineering Geomatics Engineering Syllabus

Geomatics Engineering syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Geomatics Engineering in GATE Civil Engineering, not a summary of it.

1. 1

   Principles of Surveying

   6 topics

   • Errors and Their Adjustment
   • Maps
     • Scale
     • Coordinate System
   • Distance and Angle Measurement
     • Levelling
     • Trigonometric Levelling
   • Traversing and Triangulation Survey
   • Total Station
   • Horizontal and Vertical Curves
2. 2

   Photogrammetry and Remote Sensing

   2 topics

   • Scale and Flying Height
   • Basics of Remote Sensing and GIS

Geomatics Engineering flashcards for GATE Civil Engineering

25 of 71 cards from the Geomatics Engineering deck — real questions with worked answers.

1. In surveying, distinguish between an error and a mistake.

   A mistake (blunder) is a gross human error caused by carelessness (e.g., misreading a staff), and it must be eliminated. An error is the small unavoidable difference between a measured value and the true value, arising from instrumental, natural, or personal limitations.

2. What are the three classes of surveying errors based on their source?

   Instrumental errors (imperfect/maladjusted instruments), natural errors (temperature, wind, refraction, magnetic variation), and personal errors (limitations of the observer's senses, e.g., bisection or reading errors).

3. Differentiate systematic (cumulative) errors from random (accidental) errors.

   Systematic errors follow a definite physical law, have the same sign under the same conditions, accumulate, and can be corrected (e.g., tape too short). Random errors are equally likely to be positive or negative, tend to cancel, and are governed by the laws of probability.

4. State the relationship between the probable error of a single observation and the number of observations $n$ for the probable error of the mean.

   The probable error of the mean $E_m = \dfrac{E_s}{\sqrt{n}}$, where $E_s$ is the probable error of a single observation. Precision improves with $\sqrt{n}$.

5. Define the most probable value (MPV) of a quantity from several direct equal-weight observations.

   The MPV is the arithmetic mean: $\bar{x} = \dfrac{\sum x_i}{n}$. It is the value with the highest probability and makes the sum of squared residuals a minimum (least squares).

6. How is the probable error of a single observation computed from residuals $v$?

   $E_s = 0.6745\sqrt{\dfrac{\sum v^{2}}{n-1}}$, where $v_i = x_i - \bar{x}$ are residuals and $n$ is the number of observations.

7. State the laws of accidental error propagation for the sum and for the product (independent quantities).

   For a sum/difference $S = a \pm b$, the error $E_S = \sqrt{E_a^{2}+E_b^{2}}$. For products, fractional errors combine in quadrature: $\dfrac{E_P}{P} = \sqrt{\left(\dfrac{E_a}{a}\right)^{2}+\left(\dfrac{E_b}{b}\right)^{2}}$.

8. What is the weight of an observation, and how does it relate to the probable error?

   Weight is the relative reliability (trustworthiness) of an observation. Weight is inversely proportional to the square of the probable error: $w \propto \dfrac{1}{E^{2}}$. For a mean of $n$ readings, weight $\propto n$.

9. Define a map and distinguish a plan from a map.

   A map is a scaled, generalized graphical representation of features of (part of) the earth's surface projected onto a plane. A plan is a large-scale representation of a small area where curvature is neglected; a map covers larger areas often at small scale and may show relief.

10. What is the difference between a topographic map and a cadastral map?

    A topographic map shows natural and artificial features including relief (contours, hills, rivers, roads). A cadastral map shows property boundaries, ownership, and land parcels, usually at a large scale for legal/revenue purposes.

11. What is a contour line, and what is the contour interval?

    A contour is an imaginary line joining points of equal elevation (reduced level) on the ground. The contour interval is the constant vertical distance between successive contours; horizontal equivalent is the corresponding horizontal distance.

12. State two important characteristics of contour lines.

    Contours close on themselves (within or outside the map); two contours of different elevation never cross or merge except at an overhanging cliff or vertical cliff; closely spaced contours indicate steep slopes, widely spaced indicate gentle slopes; a contour crossing a valley forms a V pointing uphill (towards higher ground).

13. Define the scale of a map.

    Scale is the fixed ratio of a distance on the map to the corresponding actual distance on the ground, expressed as $1:n$ (representative fraction) or as an engineer's/graphical scale. Example: $1\text{ cm} = 100\text{ m}$ is $1:10000$.

14. What is the Representative Fraction (R.F.)?

    R.F. is the scale expressed as a dimensionless fraction $\text{R.F.} = \dfrac{\text{map distance}}{\text{ground distance}}$, with both in the same units. A smaller R.F. (e.g., $1:50000$) means a smaller-scale map covering a larger area.

15. Differentiate a large-scale map from a small-scale map.

    A large-scale map has a large R.F. (e.g., $1:1000$), shows a small area with great detail. A small-scale map has a small R.F. (e.g., $1:1000000$), covers a large area with less detail.

16. What is a scale factor, and why does the area scale differ from the linear scale?

    The linear scale factor is the R.F. $1:n$. Because area scales with the square of length, the area scale is $1:n^{2}$. Thus a map at $1:1000$ represents ground area at $1:10^{6}$.

17. How is the area on the ground obtained from the area measured on a map of scale $1:n$?

    Ground area $=$ (map area) $\times n^{2}$. For example, $1\,\text{cm}^{2}$ on a $1:5000$ map represents $5000^{2}\,\text{cm}^{2}=2.5\times10^{7}\,\text{cm}^{2}=2500\,\text{m}^{2}$.

18. What is a diagonal scale and what does it allow?

    A diagonal scale uses the principle of similar triangles to subdivide a unit into a second order of smaller divisions, allowing measurement to three units (e.g., metres, decimetres, centimetres) with one scale.

19. Define a vernier scale and the least count of a vernier.

    A vernier is an auxiliary scale sliding along a main scale to read fractional parts of the smallest main-scale division. Least count $= \dfrac{\text{value of one main-scale division}}{\text{number of vernier divisions}}$.

20. What is a coordinate system in surveying, and name two common types.

    A coordinate system defines positions of points relative to reference axes/origin. Common types: rectangular (Cartesian) coordinates—Easting and Northing $(E, N)$; and polar coordinates—a distance and a bearing/angle from a reference.

21. Give the formulas to convert a line's length $L$ and whole-circle bearing $\theta$ into latitude and departure.

    Latitude (N–S component) $= L\cos\theta$; Departure (E–W component) $= L\sin\theta$. Latitude is positive towards North, departure positive towards East.

22. How do you compute the length and bearing of a line given coordinates $(E_1,N_1)$ and $(E_2,N_2)$?

    $L=\sqrt{(E_2-E_1)^{2}+(N_2-N_1)^{2}}$ and bearing $\theta = \tan^{-1}\!\left(\dfrac{E_2-E_1}{N_2-N_1}\right)$ (the departure over latitude), with quadrant adjusted by signs of $\Delta E$ and $\Delta N$.

23. Differentiate a whole-circle bearing (WCB) from a reduced bearing (quadrantal bearing).

    WCB is measured clockwise from North, ranging $0^{\circ}$ to $360^{\circ}$. Reduced bearing is measured from North or South towards East or West, ranging $0^{\circ}$ to $90^{\circ}$, and requires a quadrant designation (e.g., $N\,40^{\circ}E$).

24. What is the difference between a fore bearing (FB) and a back bearing (BB)?

    FB and BB of a line are observed from the two ends in opposite directions. They differ by $180^{\circ}$: $\text{BB}=\text{FB}\pm180^{\circ}$ (add if FB $<180^{\circ}$, subtract if FB $>180^{\circ}$).

25. Define magnetic declination.

    Magnetic declination is the horizontal angle between true (geographic) north and magnetic north at a place. True bearing $=$ magnetic bearing $\pm$ declination (E declination added, W declination subtracted).

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