## Introduction to Geographic Information Systems by Chang 9th Edition-Test Bank

Introduction to Geographic Information Systems, 9e (Chang)

Chapter 6 Geometric Transformation

1) Why is geometric transformation important in GIS?

2) You have digitized a layer from a USGS 7.5-minute quadrangle map including the four corner tics of the map with known longitude and latitude values. Describe the steps you will follow to transform the digitized layer into UTM coordinates.

3) Explain image-to-map transformation.

4) The affine transformation allows rotation, translation, skew, and differential scaling. Describe what differential scaling does.

5) Operationally, the affine transformation of a satellite image involves three sequential steps. What are these steps?

6) What are the actual and estimated coordinates of the control points in a map-to-map transformation?

7) What are the actual and estimated coordinates of the ground control points in an image-to-map transformation?

8) Define the “root-mean-square (RMS) error” in geometric transformation.

9) Geometric transformation is typically an iterative process. Why?

10) Describe a scenario, in which the RMS error may not be a reliable indicator of the goodness of a map-to-map transformation.

11) Why do we have to perform the resampling of pixel values following an image-to-map transformation?

12) What is pyramiding?

13) Which transformation method is most commonly used in GIS?

A) Equiarea transformation

B) Similarity transformation

C) Affine transformation

D) projective transformation

Answer: C

14) A geometric transformation of a newly digitized map normally requires a minimum of ________ control points:

A) 1

B) 2

C) 4

D) 6

Answer: D

15) Mathematically, the affine transformation uses a pair of:

A) first-order polynomial equations

B) second-order polynomial equations

C) third- or higher-order polynomial equations

Answer: A

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