ENEV 281 – Chapter 2 - Surveying, Mapping, and Information Systems

Vocabulary flashcards covering measurements, units, computations, and error analysis in surveying based on Chapter 2 notes.

SI

Standing for "Système International," it refers to the metric units of measurement used by most countries in the world.

Angle

A figure formed by the intersection of two lines, typically measured in degrees, minutes, and seconds.

Kilometer (km)

A metric unit of distance equal to $1,000$\text{ meters} ($m$).

Millimeter (mm)

A metric unit of distance equal to $0.001$\text{ meter} ($m$).

Centimeter (cm)

A metric unit of distance equal to $0.01$\text{ meter} ($m$).

Decimeter (dm)

A metric unit of distance equal to $0.1$\text{ meter} ($m$).

Hectare (ha)

A metric unit of area equal to $10,000\,m^2$, which is approximately $2.471\text{ acres}$.

Significant Figures

The number of digits in a recorded measurement that imply a specific degree of exactness obtained by the measuring instrument.

Rounding Rule for 5 or Higher

If the first extra digit is $5$ or more, add $1$ to the last digit of the rounded solution.

Rounding Rule for Less than 5

If the first extra digit is less than $5$, it is dropped along with any additional digits to the right.

Blunder

A significant mistake caused by human error, also referred to as a gross error.

Systematic Errors

Repetitive errors caused by equipment imperfections, observation methods, or environmental factors that are constant in magnitude and direction.

Accidental Errors

Also known as random errors, these are the differences between a true quantity and a measurement free from blunders or systematic errors; they are not constant in magnitude or direction.

Most Probable Value

The average value of different measurements of the same quantity, as long as each measurement is equally reliable.

The 95 Percent Error ($E_{95}$)

A range of random errors calculated using the formula $E_{95} = 1.96 \times \sqrt{\frac{\sum \Delta^2}{n(n-1)}}$.

Law of Compensation

The property that accidental errors tend to accumulate in proportion to the square root of the number of measurements, defined as $E = E_1 \times \sqrt{n}$.

Precision

The degree of perfection used in the survey process, often evaluated by standard deviation.

Accuracy

The degree of perfection obtained in the results of the survey, often evaluated by the mean.

Error of Closure

The difference between the actual measurement and the true value.

Relative Accuracy

A ratio calculated as $1 : \frac{D}{C}$ where $D$ is the distance measured and $C$ is the error of closure.

Foot to Metric Conversion

The exact relationship where $1\,ft = 0.3048\,m$.

Inch to Metric Conversion

The exact relationship where $1\,inch = 25.4\,mm$.

Mile

A linear measurement in foot units equal to $5,280\,feet$ or $1,760\,yards$.

Rod

A linear measurement in foot units equal to $16.5\,feet$.

Chain

A linear measurement in foot units equal to $66\,feet$ or $100\,links$.

Acre

A unit of area equal to $43,560\,ft^2$ or $10\text{ square chains}$.

One Degree

An angular measurement equal to $60'$ (minutes).

One Minute

An angular measurement equal to $60''$ (seconds).

Gon

An angular measurement unit where one revolution equals $400.0000\,gon$, used in some European countries.

Absolute Accuracy Standard (Canada)

The position of any monument defining a boundary must be within $+/- 0.02\,metres$ or better at a $95\%$ confidence level.