Geographical Techniques Questions and Answers

Answer: C

The parallelepiped, minimum distance to mean and Gaussian maximum likelihood classifiers are all standard supervised techniques: each needs training samples of known classes to set its decision rule. By elimination, neural network analysis is the option the key names as not a supervised technique, so it is the answer. Neural networks can in fact be trained with or without labelled samples, which is why the question is loosely worded, but it is the only item of the four that is not a classical supervised classifier.

Answer: B

In spatial analysis the common geographic patterns are centralized (clustered), linear and random, with dispersed or regular patterns as a counterpart. Distributive is not considered to be a geographic pattern in this classification, so it is the answer to a question that asks for the one that is not. The other three describe how features are arranged on the ground: around a centre, along a line, or without order. A distribution of points can be centralized around a core, spread along a line like a road, or random, with no regular order.

Answer: B

The measures of central tendency are the arithmetic mean, the median and the mode, which describe the centre or typical value of a set of data. The mean deviation is a measure of dispersion, because it gives the average distance of the values from a central value, so it is not a measure of central tendency. The answer is the mean deviation. Range, quartile deviation, mean deviation and standard deviation all belong to the group of dispersion measures, which show how much the values differ from their centre.

Answer: D

IRS-P4, launched in 1999, is also known as Oceansat-1, as it carried an ocean colour monitor and a multi-frequency scanning microwave radiometer for studying the oceans. Resourcesat is the name of IRS-P6, and Edusat is a communication satellite for education. Remotesat is not an Indian satellite name. The answer is Oceansat. The IRS-P series included IRS-P2, P3, P4 and P6, and each carried sensors chosen for a particular use such as oceans, resources or stereo mapping.

Answer: C

Centrographic measures are the techniques of locating the centre of a spatial distribution, such as the mean centre, the median centre and the standard distance. The mean centre is the average of the x and y coordinates of the points, so it is a centrographic measure. The geometric mean and the arithmetic mean are ordinary statistical averages, and the standard deviation is a measure of spread of data values and not a location of the centre.

Answer: B

The representative fraction is large when the denominator is small, since a small denominator means each map unit stands for a smaller ground distance and so more detail. Among 1:250,000, 1:25,000, 1:500,000 and 1:50,000, the smallest denominator is 25,000, so 1:25,000 is the largest scale. The scale 1:500,000 is the smallest of the four. A large scale map covers a small area in great detail, while a small scale map shows a wide area with less detail, so a topographical sheet of 1:25,000 shows more than one of 1:250,000.

Answer: C

Assertion (A) is accepted as correct in the key, as raster data processing, such as overlay and map algebra, is computationally efficient. Reason (R) is false: raster data are simple in structure, but the key does not accept this as a true reason for the efficiency, treating the statement as incorrect. So the key gives that (A) is correct but (R) is false, which is code C. Code A and B accept the reason, and code D rejects the assertion.

Answer: A

The original map is at 1/50,000 and the new map is at 1/250,000. The ratio of the new scale to the old scale is:

\[ \frac{1/250000}{1/50000} = \frac{50000}{250000} \]

\[ = \frac{1}{5} \]

The new map is a reduction to one fifth of the linear size of the original, so reduction 1/5 is the answer. An enlargement would need a larger fraction than 1/50,000, and 1/10 would be the ratio for a map at 1/500,000. The same result is found by dividing 250,000 by 50,000, which gives 5, so the linear size of the map is reduced five times.

Answer: D

A correlation coefficient of +0.99 shows a very high positive relationship, +0.50 a moderate one and -0.01 a very low (almost no) relationship. A coefficient of -0.99 is a very strong negative correlation, not no relationship, so the pair - 0.99 and Nil is wrongly matched. The nil degree of relationship is shown by a value close to zero, so this is the answer to the question asking which is not correctly matched. The sign of the coefficient gives the direction and its size gives the degree, so a large negative value is a high degree of negative correlation.

Answer: C

IRS-1A, the first of the Indian Remote Sensing satellites, was launched on 17 March 1988 from the Baikonur cosmodrome in the Soviet Union. IRS-1B followed in 1991. The years 1982 and 1987 are before the launch, and 1990 does not match, so 1988 is the answer. The Indian Remote Sensing programme later added IRS-1B, IRS-1C and IRS-1D, and the series has supported mapping of crops, forests, water and land use.