List of top Geo Informatics Engineering Questions asked in GATE Geomatics Engineering

The error matrix resulting from randomly selected test pixels for a classified image is given below.
The Producer’s accuracy of class 1 is % (rounded off to 1 decimal place).

		Reference Data
		Class 1	Class 2	Class 3	Class 4
Classified Data	Class 1	320	8	7	3
	Class 2	12	270	6	2
	Class 3	9	6	410	5
	Class 4	14	2	3	350

The brightness values of four pixels in the input image are shown in the table below. The image is rectified using nearest neighbor intensity interpolation, and the pixel at location (5, 4) in the output image is to be filled with the value from coordinate (5.3, 3.7) in the input image. The brightness value of the pixel at location (5, 4) in the rectified output image is 11. (Answer in integer)

Location of pixels in input image (Row, Column)	Brightness Value
(5, 3)	9
(5, 4)	11
(6, 3)	14
(6, 4)	12

In case of normalized difference vegetation index (NDVI), which of the following statements is/are correct?

A remote sensing image is acquired from an IRS series satellite. Initially a two-dimensional filter with transfer function $ H(u,v) = \exp\left(\frac{-D^2(u,v)}{2D_0^2}\right) $ is applied to reduce scan line effects. Here $ D(u,v) $ is the distance from the center of the frequency rectangle, and $ D_0 $ is the cutoff frequency. Which one of the following will be the transfer function for the corresponding filter to detect the edges in the image?

A CCD array element in a remote sensing sensor measures incoming radiation and its output voltage varies linearly between 0 V to 5 V. This voltage is converted to an 8-bit digital image using an analogue to digital convertor (ADC). The ADC has a linear response without bias or noise. If the output image pixel has a digital number of 100, the input voltage to the ADC would be __________ V (rounded off to 2 decimal places).

Clouds appear white in optical visible spectral bands of remote sensing images due to _________ scattering.

A remote sensing instrument measures only in Green, Red and Near-Infrared frequency bands. The remote sensing index/indices that CANNOT be derived using data of this instrument is/are:

Which one of the following is NOT used to assess the quality of remote sensing image?

In the grid below, the four corners A, B, C and D are the pixel locations on an image. The brightness values at pixels A, B, C and D are 10, 20, 5 and 30, respectively. Using bilinear interpolation, the brightness value determined at point P is ................. (Rounded off to 1 decimal place).

The variance–covariance matrix for a 3-band image is given below (bands in the order 1, 2, 3). Which of the statement(s) is/are CORRECT? \[ \Sigma = \begin{bmatrix} 9 & 2 & 4 \\ 2 & 9 & -3 \\ 4 & -3 & 9 \end{bmatrix} \]

Consider the histogram of an 8-bit image given below at (1). A piece-wise linear contrast stretch given at (2) is applied on the said image. The minimum and maximum pixel values of the image obtained after applying the given contrast stretch are ................. (minimum value) and ................. (maximum value), respectively.

The contingency table below is obtained after an image classification. The overall classification accuracy ($O$) is given as

The value at the center pixel of the image at (1) obtained after applying the filter given at (2) is ..................

A perfectly adjusted tacheometer is set at a point A having Reduced Level (RL) of 80.50 m and the following readings are taken to the staff held at point B having RL of 80.10 m.

The height of the instrument from the ground above point A is \underline{\hspace{1.8cm}} m (Rounded off to 2 decimal places).

A pair of overlapping vertical photographs were taken from a flying height of $1230~\text{m}$ above sea level with a camera having a focal length of $152.4~\text{mm}$. The distance between the consecutive exposure stations is $350~\text{m}$. The parallax bar reading of a point A on the photograph is observed as $10.96~\text{mm}$. The parallax bar constant for this setup is given as $80.71~\text{mm}$. The elevation of point A above sea level is ___________ m (Rounded off to 2 decimal places).

Following is the page of a field book used for levelling. Few readings marked with ‘-’ are illegible. The Reduced Level (RL) of the Temporary Bench Mark (TBM) is ................. m (Rounded off to 2 decimal places). All the readings are in m.

Find the best match between Column 1 and Column 2 \[ \begin{array}{lcl} \textbf{Column 1} & & \textbf{Column 2} \\ \text{P: Trilateration} & & 1. \ \text{Measurements of lengths and directions of all sides} \\ \text{Q: Triangulation} & & 2. \ \text{Measurements of all the sides of a triangle} \\ \text{R: Traversing} & & 3. \ \text{Measurements of all the interior angles of a triangle} \\ \text{S: Resection} & & 4. \ \text{Determination of occupied position with the help of known stations} \end{array} \]

An aerial photograph is to be taken from a flying height of $2~\text{km}$ above a flat ground with a camera having a focal length of $200~\text{mm}$. The image format used is $23~\text{cm} \times 23~\text{cm}$. The ground area covered by a single photograph is \underline{\hspace{1.6cm}} $\text{km}^2$.

The following vertical circle readings were taken by a theodolite set up at station A to observe targets located at P and Q. Find the vertical angle $PAQ$.

Which of the following triangles are well conditioned and may be suitable for control establishment using triangulation?

A square grid is laid on a flat terrain and is photographed from an aerial camera. The flying height and camera parameters are assumed to be constant. The camera and lens are assumed to be perfect (i.e. free from any distortions). The image of the grid obtained from the camera is shown below. Select the CORRECT statement from the statements given below.

The bearing of the line $AB$ from North is $143^\circ 40'$ and angle $ABC$ measured in clockwise direction is $309^\circ 30'$. The bearing of line $BC$ in Quadrantal Bearing System is ____________

For a profile given in the figure in the form of three steps A, B and C, the following information is available:
Height of step A ($H_A$) with respect to a reference line = 10 m (known and error free)
Difference in height between step A and step B ($h_1$) = 5 m $\pm$ 2 mm
Difference in height between step B and step C ($h_2$) = 8 m $\pm$ 3 mm
$H_B$ and $H_C$ are the unknown heights of step B and C, respectively. The step B is higher than step C and D.
The coefficient of correlation, $\rho_{h_1 h_2}$, between the height differences = 0.25
The coefficient of correlation between estimated heights of points B and C ($\rho_{H_B H_C}$) will be ............................. (Rounded off to 2 decimal places).

For a push-broom (along-track) sensor the following are known:
Field of view (FoV) = 2 degrees
Instantaneous FoV = 1 milli-radian
Time to scan one full scanline = $2 \times 10^{-2}$ s
Height above ground = 100 km
The dwell time for a single pixel of this sensor is ............................. s. (Rounded off to 2 decimal places)

Consider the Sun and the Earth as blackbodies at $6000~\text{K}$ and $300~\text{K}$ temperatures, respectively. Which of the following statement(s) is/are INCORRECT?