(CH. 5 Canvas Material) Major Test B Study Guide - SRVY 2331

Material pulled from Canvas to make a study guide

What are the three Earth surfaces surveyors must understand?

Topographic surface, geoid, and ellipsoid

What is geodesy?

The science of measuring the Earth's size, shape, gravity field, and orientation in space

What is ECEF?

Earth-Centered Earth-Fixed coordinates with the origin at the geocenter

Where is the origin of ECEF?

The geocenter, the Earth's center of mass

What does the ECEF Z-axis point toward?

The International Reference Pole, IRP

What are the three types of latitude?

Geocentric, geodetic, and astronomic

What is geocentric latitude measured to?

A line from the point to the Earth's center

What is geodetic latitude measured to?

The ellipsoid normal

What is astronomic latitude measured to?

The plumb line

What is the deflection of the vertical?

The angle between the plumb line and the ellipsoid normal

What is an oblate spheroid?

An ellipse rotated about its minor axis

What is the formula for flattening?

f = (a − b) / a

What is the semi-major axis, a?

The equatorial radius of the ellipsoid

What is the semi-minor axis, b?

The polar radius of the ellipsoid

What ellipsoid and initial point were used by NAD27?

Clarke 1866 and Meades Ranch, Kansas

What is a geocentric datum?

A datum whose origin is at the Earth's center of mass

What is the geoid?

The equipotential surface of the Earth's gravity field that best fits mean sea level

What is geoidal undulation, N?

The separation between the geoid and ellipsoid

What ellipsoid is used by NAD83?

GRS80

What datum are GPS navigation messages based on?

WGS84

What is the major difference between NAD83 and WGS84/ITRF?

NAD83 is about 2 meters offset from the true geocenter

What is CORS?

Continuously Operating Reference Stations that continuously collect GNSS data

What is HARN?

High Accuracy Reference Network used to upgrade NAD83 with GPS observations

What is ITRF?

International Terrestrial Reference Frame

What organization maintains ITRF?

IERS

What geodetic techniques contribute to ITRF?

GNSS, VLBI, SLR, DORIS, and LLR

What three things must be given for coordinates to be completely defined?

Reference frame, frame reference epoch, and coordinate epoch

What does OPUS do?

Processes GNSS observations using nearby CORS stations

What does HTDP do?

Moves coordinates between reference frames and epochs

What does NATRF2022 replace?

NAD83

What does NAPGD2022 replace?

NAVD88

What four map properties cannot all be preserved by a projection?

Area, shape, scale, and direction

What is a conformal or orthomorphic projection?

A projection that preserves shape and angles

Which projection is best for states that are long east-west?

Lambert Conformal Conic

Which projection is best for states that are long north-south?

Transverse Mercator

What is a secant projection?

A projection whose surface cuts through the ellipsoid

What is the elevation factor formula?

EF = R / (R + h)

What is the combined factor formula?

CF = EF × k

What is the grid distance formula?

Grid Distance = Ground Distance × CF

What is the ground distance formula?

Ground Distance = Grid Distance ÷ CF

How wide is a UTM zone?

6 degrees of longitude

How many UTM zones are there?

60

What is the UTM central meridian scale factor?

0.9996

What is the UTM false easting?

500,000 meters

Which UTM zones cover the conterminous United States?

Zones 10 North through 19 North

Which UTM zone contains Tyler, Texas?

Zone 15

What is ellipsoidal height, h?

Height above the ellipsoid

What is orthometric height, H?

Height above the geoid

What is geoid height, N?

The separation between the geoid and ellipsoid

What is the orthometric height formula?

H = h − N

What vertical datum did NAVD88 replace?

NGVD29

What will NAPGD2022 replace?

NAVD88

What unit was eliminated on January 1, 2023?

The U.S. survey foot