# GIS-3015 Chapter Notes - Chapter 2: United States Geological Survey, Lambert Conformal Conic Projection, Map ProjectionPremium

4 pages42 viewsFall 2018

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**preview**shows page 1. to view the full**4 pages of the document.**Assignment 02

Useful material for answering Q1 and Q2

Key distance conversions:

Conversions between different units of measurement are also an important part of scale and

distance calculations.

Key conversions are listed below:

• 1 inch = 2.54 centimeters

• 1 statute mile = 5,280 feet = 63,360 inches

• 1 statute mile = 1.609 kilometers

• 1 kilometer = 100,000 centimeters

• 1 nautical mile = 6,076.1 feet

• 1 foot = 12 inches

• 1 meter = 100 centimeters

Explanation of representative fraction

Map scale is defined as the mathematical relationship between a unit of distance on the map

and its corresponding distance on the ground. The ratio of map distance to ground distance, both

in the same units of measurement, is called the representative fraction (RF) for the map. It is

computed from the following equation:

1/X = map distance (md) / ground distance (gd)

We will use this equation in the following scale problems. Hence, an RF of 1/24,000

means that 1 centimeter on the map represents 24,000 centimeters on the ground, 1 inch on the

map represents 24,000 inches on the ground, and so on for other units of distance measurement.

The RF can also be written as 1:24,000.

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