Geog 160 Final

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B) Difference

Which of the following operations selects only those records that appear in one, but not both, of the source files?
A) Intersection
B) Difference
C) Union

GIS

a computer-based tool used to help people transform geographic data into geographic information.

vector

involves sampling locations at intervals along the length of linear entities (like roads), or around the perimeter of areal entities (like property parcels). When they are connected by lines, the sampled points form line features and polygon features that approximate the shapes of their real-world counterparts.

raster

involves sampling attributes at fixed intervals. Each sample represents one cell in a checkerboard-shaped grid.

A) Intersection

Which of the following operations selects only those records that appear in both of the source files?
A) Intersection
B) Difference
C) Union

A) Raster

a list of longitude and latitude coordinates that define the boundary of one Pennsylvania County--are they vector or raster data?

Raster

Which does your computer screen display, raster or vector data?

vector

Which representation strategy is better suited to representing property parcels-Raster or Vector?

B

One of the distinguishing characteristics of geographic data is that they represent phenomena that are distributed across a continuous surface. What is the most important implication of continuity?

A) The composition of the Earth's surface are continuously changing.
B) There are an infinite number of locations on the Earth's surface.
C) There are no gorges, canyons, or crevasses on the Earth's surface.
D) Geographic data must be continuously updated.

A

A distinguishing characteristic of geographic data is that the phenomena they represent are distributed over a spherical, or nearly spherical, surface. What is the most important implication of the Earth's shape?

A) The more accurately we wish to specify positions, the more precisely we must account for the Earth's irregular shape.
B) Angles and distances calculated on plane coordinates are more accurate than angles and distances calculated on geographic coordinates.
C) Geographic coordinates are more precise than plane coordinates.
D) The only distortion-free way to transform geographic coordinates into plane coordinates involves sets of mathematical formulae called map projections.

B

A unique characteristic of geographic data is that attributes such as terrain elevation, soil type, and even property value tend to be similar among neighboring locations. This property allows us to estimate unknown attribute values from nearby known values. What is the property called?

A) Scale independence
B) Spatial dependence
C) Spectral reflectance
D) Sheer coincidence

1:50,000

*First convert 3.5 kilometers (the ground distance) to 350,000 centimeters so that the units cancel each other out. Then divide 350,000 by 7 to reduce the map distance to 1.

The distance between the Lincoln Memorial and the U.S. Capitol measures 7 centimeters on a map of Washington, D.C., and 3.5 kilometers on the ground. Calculate the scale of the map.

1:300,000,000

*: First convert map distance (the width of the map) and ground distance (the circumference of the Earth) to the same units. Then reduce the map distance to 1 by dividing both the numerator and the denominator by it.

What the nominal scale of the 5.25 inch-wide (13.3 centimeters) world map shown above? Hint: the circumference of the Earth is 40,030 kilometers (24,875 miles).

2,000 inches

Start by setting up an equality between the representative fraction (1/100,000) and the ratio of map distance (.02 inches) to ground distance (Dg). Then cross-multiply the ground distance and the scale denominator (0.02 inches x 100,000 = Dg) 1).

National Map Accuracy Standards guarantee that 90 percent of well-defined points tested on U.S.G.S. topographic maps at 1:20,000 or smaller scale will be within 0.02 inches (map distance) of their true horizontal positions. In terms of ground distance, what is the maximum allowable error for well-defined points in the 1:100,000-scale map series?

1:38,000

*Start by setting up an equality between the representative fraction (1 / scale denominator, the unknown) and the ratio of focal length (6 inches) to the difference between flying height and average elevation flying height (20,000 feet - 1,000 feet). Convert the focal length and flying height to the same units. Then cross-multiply and solve for the scale denominator.

Calculate the average scale of a vertical aerial photograph taken with a camera whose focal length is 6 inches at an altitude of 20,000 feet where the average terrain elevation in the scene is 1,000 feet.

1:20,000

*Sp = f / (H-h) = 0.5' / (12000'-2000') = 1:20000

Say you have an aerial image that was taken with a 6-inch focal length camera at a flying height of 12,000 feet above sea level. At a certain point of the photograph, however, the terrain rises to an elevation of 2000 feet above sea level. What is the scale of that part of the photo?

-77.8681° longitude and 40.7933° latitude

*Convert seconds to fractions of a minute, then minutes to fractions of a degree. Then apply the minus sign for longitudes in the western hemisphere, and latitudes in the southern hemisphere.

Convert 77°52'05" W longitude and 40°47'36" N latitude to decimal degrees.

horizontal datum

An alignment of a coordinate system grid with a geometrical figure that approximates the Earth's size and shape is know as a:

Geoid

A mathematically complex three-dimensional figure across which gravity is everywhere equal whose size and shape closely approximates global mean sea level.

Ellipsoid

A mathematically simple three-dimensional figure used to approximate the Earth's size and complex shape.

vertical datum

Mean sea level, which is used as a reference surface for the measuring elevations.

The GRS 80 ellipsoid replaced the Clarke 1866 ellipsoid. The slightly different approximation of the Earth's size and shape caused the geographic coordinate system grid to shift relative to control point locations, necessitating adjustment of the control point coordinates.

explain the change from NAD 27 to NAD 83

ellipsoid

Plane coordinate system grids (such as UTM and SPC) are projected, but only after they have been referenced to an ______.

10-100 meters

Approximately how much did positions of points (in the conterminous U.S.) shift as a result of the National Geodetic Survey's adjustment from NAD 27 to NAD 83?

Project the GPS data to UTM.

You wish to superimpose point data you produced with a hand-held GPS unit over a digital orthophoto that is encoded in UTM coordinates and the NAD 83 datum. What needs to be done?

Plane coordinate transformation

You have scanned an unrectified aerial photograph from the 1940s that you wish to georegister with an existing parcel database for an analysis of land use change. The parcel database is encoded as State Plane Coordinates based upon a Lambert projection and the NAD 83 datum. What needs to be done to the scanned air photo?

Datum transformation

You wish to georegister a USGS Digital Line Graph (DLG), in UTM and NAD 27, with other National Map data layers in UTM and NAD 83. What needs to be done to the DLG?

A

The United States Geological Survey offers Landsat satellite image data for sale at a range of prices. "Raw uncorrected" data are cheapest. "Systematically corrected" data cost more. (This is true for commercial satellite data vendors as well.) Which of the following does systematic correction involve?

A) Plane coordinate transformation
B) Datum transformation
C) Map projection
D) Datum transformation and map projection

5,000,000 meters North

*The distance between the equator and the poles is very nearly 10,000,000 meters. 45° North latitude is midway between the equator and the North Pole.

What is the UTM Northing that corresponds to 45° North latitude?

500,000 meters East

*both the north and south halves of every UTM zone are defined as 500,000 meters west of the zone central meridian.

What is the UTM Easting that corresponds to the central meridian of each UTM zone?

The North Pole is undefined in all 60 UTM zones.

What are the UTM coordinates of the North Pole?

84° 30'

UTM zones do not extend above __° __' North latitude. Locations in higher latitudes are specified in a polar coordinate system that is based on the Polar Stereographic map projection

6° of longitude

*Since the circumference of the Earth spans 360° of longitude, and there are 60 UTM zones, the width of a single zone must be 6° (360°÷60).

What is the east-west span (i.e., "width") of each UTM coordinate system zone?

500,000 meters

what is the distance from the origin of a UTM zone to the central meridian?

500,000 meters west of the intersection of the central meridian and the equator

Where is the origin of the north half of each UTM coordinate system zone located?

10,000,000 meters south of the equator and 500,000 meters west of the central meridian

Where is the origin of the south half of each UTM coordinate system zone located?

Along the two standard lines

Where is scale distortion minimized in each UTM zone?

zero; central meridian

Scale distortion associated with the Transverse Mercator map projections upon which UTM coordinate system zones are based is ____ along the two standard lines that parallel each zone ______, 180,000 meters to the west and east

At the points that are farthest from the two standard lines

Where is scale distortion greatest in each UTM zone?

Point A

*Although it has the smaller Easting, Point A lies to the east of Point B because Zone 31 is east of Zone 30. Recall that UTM zones are number 1-60 from west to east, starting at 180°

The UTM coordinates of point A are 400,000 meters East, 4,500,000 meters North, Zone 31 North. The coordinates of point B are 600,000 meters East, 4,500,000 meters North, Zone 30 North. Which is the easternmost point?

Metric (meters)

Which "unit of measure" is used to specify positions in the State Plane Coordinate System of 1983?

National (U.S.)

What is the extent of the State Plane Coordinate System?

1 part in 10,000

SPC, like other plane coordinate systems, is based upon map projections. All plane coordinate systems contain a certain amount of positional error due to the scale distortion inherent in map projections. What is the maximum error associated with SPC zones?

1 part in 2,500

what is the maximum error at the central meridian of UTM coordinate system zones.

Yes, scale distortion is zero along the standard line(s).

Are there any positions in a SPC zone that are free from scale distortion? If so, where?

standard line

a line of latitude, longitude, or other line along which scale distortion associated with a map projection is zero.

Lambert Conic Conformal, standard parallels 42° 04' and 43° 16'

Upon what map projection is the Iowa North zone based?

8,158,179 meters North
240,205 meters East
Nevada East zone

Use the National Geodetic Survey's Geodetic Toolkit to convert the following geographic coordinates to State Plane Coordinates: 36° 10' 30" N, 115° 08' 11" W, NAD 83

conformal projections

Angles measured at points on the globe are represented correctly on _________. The distortion ellipses vary in size, but not in shape. The relative sizes of landmasses are distorted in order to preserve their shapes

Equidistant

_________ projections like this include one, or at most two, points from which straight lines in all directions are true to scale. In this case, the one point is 90 degrees North latitude. Notice that the north-south axes of the distortion ellipses are all the same length on this projection. This means that the scale of the map is true along every meridian.

plate carree

the simplest transformation of positions on the globe to a plane

compromise

allows between the four properties (conformal, equivalent, equidistant, azimuthal) that minimizes deformation in most areas of the globe.

equal-area

________ projection depicts the sizes of the landmasses in correct proportion to how they appear on the globe. Although the shapes of the distortion ellipses vary, their areas are equivalent. The shapes of the landmasses are distorted, even as their correct areas are preserved.

cylindric

________ projection preserves the property of conformality. The relative sizes of landmasses are distorted, but their shapes are preserved. Angles measured at points on the globe are represented correctly everywhere on the projection.

pseudocylindric

______ projection preserves the property of equivalence of area. The sizes of the landmasses are shown in correct proportion to how they appear on the globe.

conic

______ projection preserves the property of equivalence of area. The sizes of the landmasses are shown in correct proportion to how they appear on the globe.

planar

______ projection preserves the property of equidistance. Straight lines drawn from the center of the projection (77 degree 51 minutes West, 40 degrees 47 minutes North) to any other point are true to scale.

Decennial Census data are actual counts; ACS data are estimates derived from samples.

What's the difference between Decennial Census ("SF 1") data and American Community Survey (ACS) data?

Ratio

*Age is neither an unranked nor ranked category. Age is a number. Is it measured at the interval level or ratio level? Zero is arbitrary in an interval level scale. Zero is not arbitrary in the context of age.

One of the questions asked in the 2010 census was "what is Person [X]'s age?" What is the level of measurement of respondents' answers to that question?

Interval

* A person born in the year 1980 is not twice as old as a person born in 1970. The year 0 AD is an arbitrary zero, not the beginning of time. Therefore year of birth is an interval level, not ratio level, measurement.

The second part of the question above in the 2010 census was "what is Person [X]'s date of birth?" What is the level of measurement of respondents' answers to that question?

Nominal

*By indicating one race or another on a census questionnaire, respondents assign themselves to unranked categories. In other words, they produce nominal data. Nominal data can be ranked only if an extrinsic set of priorities or preferences is imposed upon them, at which point they become ordinal level data.

Question : "what is Person [X]'s race?" What is the level of measurement of respondents' answers to that question?

Ordinal

*The answers are ranked categories. The data say that one person's ability to speak English is greater or less than another person's ability, but not twice or half as great.

Question: "how well does this person speak English?" Allowable answers include "Very well; Well; Not well; Not at all." What is the level of measurement of the allowable answers?

Nominal

*By indicating a country of birth, respondents assign themselves (or their fellow householders) to unranked categories.

Question: "where was this person born?" Respondents were asked to name a U.S. state or foreign country. What is the level of measurement of respondents' answers to that question?

Interval

*Insofar as the year 0 is an arbitrary zero, year of arrival is an interval level measurement, not a ratio level one.

Question: "when [what year] did this person come to live in the United States?" What is the level of measurement of respondents' answers to that question?

Nominal

*Occupations are unranked categories.

Question:"[describe] this person's chief job activity or business last week." Allowable answers include "private for-profit; private non-profit; local, state or federal government, self-employed, or working without pay." What is the level of measurement of the allowable answers?

Ratio

*You can tell that income is a ratio level measurement, not interval, because zero is not an arbitrary value. Zero dollars mean no income.

Question: "what was this person's income in the past 12 months?" What is the level of measurement of respondents' answers to that fill-in-the-blank question?

Interval and Ratio

Subtracting one value from another can appropriately be performed upon data produced at which level(s) of measurement? (More than one answer may be correct; select all correct choices.)

Interval and Ratio

*Adding the codes that signify land use categories (nominal) or average precipitation ranges (i.e., 0-10 cm, 11-20 cm, etc.; ordinal) makes no sense.
It should also be obvious that the sums of ratio-level data, which represent positions along a number line with a natural zero, are meaningful quantities.
Sums of interval-level quantities can be meaningful or absurd. Say you worked in a planning department, for example, and were tasked to map the ages of buildings within a central business district. You might symbolize the individual property parcels by the year in which each building was built. It would make no sense to sum the years and report a "total age" of each city block. On the other hand, it would make sense to report the average year of building construction by summing all the years, then dividing by the number of parcels.

Adding one value to another can appropriately be performed upon data produced at which level(s) of measurement? (More than one choice may be correct; select all correct choices.)

Interval and Ratio

*Interval and ratio data are frequently grouped into ordinal level categories for thematic mapping. Categories of nominal and ordinal data can be grouped into fewer categories, but this is not quite the same as classification.

Classifying values into ranked categories for thematic mapping can appropriately be performed upon data produced at which level(s) of measurement? (More than one choice may be correct; select all correct choices.)

Nominal, Ordinal, Interval, and Ratio

Isolating one or more categories can appropriately be performed upon data produced at which level(s) of measurement? (More than one choice may be correct; select all correct choices.)

Nominal and Ordinal

Grouping categories into fewer categories can appropriately be performed upon data produced at which level(s) of measurement? (More than one choice may be correct; select all correct choices.)

Chloropleth (Graduated Color) map

What type of map is this?

Ratio

*Counts, rates, and densities are ratio level, not interval, because zero is not an arbitrary value in any of the three cases.

Counts, rates, and densities data are all measured at what level?

Choropleth (Graduated Color)=preferred for rate and density data.

Which type of thematic map is conventionally used for population change?

American Community Survey

a continuous, nationwide survey of the demographic, economic, social, housing, and financial characteristics of the U.S. population.

1, 3, and 5

American Community Survey data products include how many year estimates? (3)

65,000; 20,000; 20,000

The Census Bureau produces 1-year estimates for geographic areas with populations of ______ or greater, 3-year estimates for areas with populations of ______ or greater, and 5-year estimates for areas with populations less than _______.

Census tracts

Census 2000 was the first in which every U.S. county was subdivided into administrative areas called _______. In all there were approximately 50,000 _______ in 2000, each of which was populated by some

Ratio

*The responses are categorical, but unlike nominal categories, they are ranked. One response can be judged to be greater than, less than, or equal to another. But two responses can not be added, subtracted, multiplied, or divided.

questions: "what were the actual sales of all agricultural products from this property?" Households were asked to respond by choosing one of the following categories: "None; $1 to $999; $1,000 to $2,499; $2,500 to $4,999; $5,000 to $9,999; $10,000 or more." What is the level of measurement of the resulting data?

Rates and Densities (e.g., migrants per 100,000 population)

Cartographers recommend that the choropleth (graduated color) mapping technique be used for thematic maps of which kind of data?

Dot Density and Proportional Symbol

Which types of thematic map do cartographers recommend to represent population?

TIGER/Line Shapefiles are in the public domain.

What constraints does the Census Bureau place on the use of TIGER/Line Shapefiles?

NO

Are terrain elevations represented with contour lines in TIGER/Line Shapefiles?

Geographic coordinates, NAD83

In which coordinate system and datum are horizontal positions specified in TIGER/Line Shapefiles?

Positions encoded in TIGER/Line Shapefiles are meant to be accurate to within 7.6 meters or better.

How accurately were horizontal positions of street centerlines specified in extracted TIGER/Line "All Lines" Shapefile after the MAF/TIGER Accuracy Improvement Project (MTAIP)?

Nodes

geometric primitive in the MAF/TIGER database: 0-dimensional, representing a landmark or street intersection, for example; a single pair of coordinates

Faces

geometric primitive in the MAF/TIGER database:2-dimensional, representing a block or county, for example

Edges

geometric primitive in the MAF/TIGER database: 1-dimensional, representing a street or river, for example

0;1;2

-Nodes are said to be __-dimensional, because they have neither length nor area.
-Edges do not occupy area, but they do have length; thus they are __-dimensional.
Faces occupy areas and are therefore __-dimensional.

Nodes and edges

Faces are composed of which geometric primitives in the MAF/TIGER database?

County or equivalent administrative area

What is the geographic coverage of a single "All Lines" TIGER/Line Shapefile?

MAF/TIGER

TIGER/Line Shapefiles are extracted from the _______ database.

a vector data set comprised of 3 or more files.

An ESRI shapefile data set is

twice

In a polygon shapefile data set, each polygon is an integrally complete feature, so any shared boundary is present _____.

ESRI

The ____ shapefile format stores points, lines, and polygons in separate data sets.

minimizes redundant data

The "persistent topology" employed in the MAF/TIGER database, to ensure topological integrity:

MAF/TIGER

Galdi (2005) explains that isolated nodes (i.e., point features) ARE stored in a separate layer from other topological elements in the ________ database. He reasons that because these points are low priority and it's not important that they be topologically integrated with Census blocks, street centerlines, etc.

single

In the MAF/TIGER topological data structure, an edge bounded by_____ adjacent face(s) is stored in order to reduce redundancy

TIGER/Line Shapefiles

A digital map data in vector form

TIGER/Line Shapefile

A ________ data set contains point, line or polygon feature representations, extracted from the MAF/TIGER database.

true

True or false? The attributes associated with polygon boundaries, such as blocks, tracts and counties, allow the user to integrate the demographic data, but the demographic data is not contained in MAF/TIGER or its shapefile extracts.

geocoding

Determining the geographic location of a street address is an example of:

routing

Calculating the shortest path between two or more nodes in a network is known as:

redisctricting

Revising voting district boundaries to ensure that districts contain equal populations is called:

digitizing

Creating digital line features that represent the streets shown on a paper map is usually called:

no

are elevation contour lines represented in TIGER/Line Files?

TIGER/Line Files?

Linear transportation features (such as streets or railroads), Hydrography (such as lakes or rivers), and Landmarks (such as select schools or churches) are all represented by _______

Positions encoded in TIGER/Line Shapefiles are meant to be accurate to within 7.6 meters or better.

How accurately were horizontal positions of street centerlines specified in extracted TIGER/Line "All Lines" Shapefile after the MAF/TIGER Accuracy Improvement Project (MTAIP)?

not projected

Are TIGER/Line data projected? If so, how?

shapefile users to use TIGER data to perform address matching.

The main reason that the Census Bureau included address range attributes in its TIGER/Line Shapefiles was to allow:

true

True or False: the linear features extracted from the MAF/TIGER database to create a TIGER/Line Shapefile actually differ, depending on the geographic level (nation, state, county).

azimuth

A direction specified by an angle between 0° and 360° measured clockwise from North is a:

closed

Positioning errors accumulated over the course of a(n) ___________ traverse can be quantified and accounted for.

100,500 meters East, 50,866 meters North

calculate the State Plane coordinates of point P. The coordinates of the nearest control point (point A) in the same SPC zone are 100,000 meters East, 50,000 meters North. The distance from the control point to point P is 1,000 meters, and the azimuth between A and P is 30 degrees. What are the coordinates of point P?

1 cm + 1 part in 100,000

What is the maximum allowable error for level C 1st order horizontal control points in the U.S. National Spatial Reference System? (This is the control order that is intended for mapping applications.)

One square centimeter

What is the precision of the position specified by the following State Plane coordinates: 500,000.00 meters East, 100,000.00 meters North?

root mean square error

A measure of the accuracy of an entire geographic data set, expressed as the average difference between many measured positions and their corresponding actual positions is

1,003 feet

*1,000 feet is the elevation at point A.
1,005 feet is the height of the instrument.

Here's the math:
HI = ZA + BS
1005 = 1000' + BS
5 = BS (backsight height = 60 inches= 5 ')
ZB = HI - FS (foresight height= 24 inches= 2')
ZB = 1005 - 2'
ZB = 1003'

calculate the elevation of point P. Your leveling instrument is positioned midway between point P and point A. The elevation of point A is known to be 1,000 feet. Looking through the telescope, you take a reading of 60 inches on the measurement rod held over point A, and 24 inches on a measuring rod held over point P. What is the elevation of point P?

orthometric height

An elevation of a point on the terrain surface above the geoid.

The combination of GPS, Galileo, and GLONASS

What is the Global Navigation Satellite System?

"space segment" of the Global Positioning System

GPS component: a constellation of orbiting satellites that transmit their locations to Earth by radio signals

Dual-frequency receivers can calculate differences in time of arrival of the L1 and L2 signals

What advantage does a dual-frequency GPS receiver provide over a single-frequency receiver?

Trilateration

Satellite ranging, the concept on which the Global Positioning System is based, is most similar to which land surveying technique?

Better than 5 meters

You spent $200 for a WAAS-enabled, hand-held GPS receiver. What is the best accuracy that you are likely to achieve?

dilution of precision

Uncertainty of GPS coordinates caused by unfavorable arrangement of the satellite constellation is known as:

1. Satellite clock
2. Ionosphere
3. Receiver clock
4. Satellite orbit
5. Lower atmosphere
6. Multipath

Rank the following sources of GPS positioning errors in descending order of their contributions to the total GPS error budget.
A) Multipath
B) Ionosphere
C) Satellite orbit
D) Receiver clock
E) Satellite clock
F) Lower atmosphere

6:00-9:00 am

Referring to the DOP graph shown above, which three-hour time of day is best for GPS positioning?

differential correction

A method for improving the accuracy of positions recorded by a mobile GPS receiver by filtering out errors recorded by a second stationary receiver is known as:

Random error

Averaging many readings is one way to improve the accuracy of GPS positioning. Averaging is effective in compensating for:

-_______ errors are likely to vary in both magnitude and direction around the actual position.

systematic error

_______ errors tend to be similar in magnitude and direction.

Coast Guard DGPS abd RTK (Real-Time Differential Correction)

Which differential correction techniques require radio connections to base stations?

When accuracies of 1 part in 1,000,000 or higher are required

When is "static" positioning preferable to "kinematic"?

accuracy

The degree to which a measured position corresponds to its actual position.

resolution

The least detectable difference in a measurement

precision

A measure of how exactly a position is defined

validity

The suitability of a set of particular data in the context of defined requirements

One square meter

What is the precision of the position specified by the following UTM coordinates: 222,222 meters East, 2,222,222 meters North

650,250 meters East, 170,433 meters North

calculate the State Plane coordinates of point P. The coordinates of the nearest control point (point A) in the same SPC zone are 650,000 meters East, 170,000 meters North. The distance from the control point to point P is 500 meters, and the azimuth between A and P is 60 degrees. What are the coordinates of point P?

surveying applications

GPS is not well suited for all ___________.

502

*Here's the math:
HI = ZA + BS
1005 = 1000' + BS
5 = BS (backsight height = 60 inches= 5 ')
ZB = HI - FS (foresight height= 24 inches= 2')
ZB = 1005 - 2'
ZB = 1003'

calculate the elevation of point P. Your leveling instrument is positioned midway between point P and point A, whose elevation is known to be 500 feet. Looking through the telescope, you take a reading of 36 inches on the measurement rod held over point A, and 12 inches on a measuring rod held over point P. what is the elevation of point P?

Multipath errors

Which kind of GPS error cannot be corrected through differential correction?

GPS satellites broadcast radio signals. GPS receivers calculate positions as a function of the difference in time between the radio broadcast and the receipt of the broadcast signal by the receiver.

How does GPS work?

control segment of the Global Positioning System

what is the network of ground receiving stations and transmitters that ensure that the geometry of GPS satellite orbits is known.

Local Governments (municipalities and counties)

In the U.S., what government agencies are responsible for large-scale mapping for infrastructure maintenance (e.g., utilities and public works) and for cadastral mapping (i.e., property boundaries)?

decrease

The USGS topographic quadrangle map of State College PA covers an area 7.5 minutes in latitude by 7.5 minutes in longitude. The map is not square, however; it measures 577 mm tall by only 440 mm wide because the length of a degree of longitude ________ as meridians converge toward the poles.

20 years

What is the average age of a 7.5-minute, 1:24,000-scale USGS topographic quadrangle map?

Horizontal and vertical control points

What is a geodetic control network?

geodetic

High-accuracy GPS positioning, which does not require line-of-site between control stations, became more accessible to _______ surveyors

vertical; oblique angle

What's the difference between a vertical aerial photograph and an oblique aerial photograph?

In a vertical aerial photo, the optical axis is______
In an oblique air photo, the optical exis forms _______ with the ground surface

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