GIS Exam 1

Frage	Antworten
Geospatial technology	Many high-tech systems that acquire, manage, store, or visualize various types of location-based data. Includes GIS, remote sensing, and GPS
GIS	Geographic information system- computer-based mapping, analysis, and retrieval of location-based data
Remote sensing	Acquisition of data and imagery from the use of satellites or aircraft
Satellite imagery	Digital images of Earth acquired by sensors onboard orbiting spaceborne platforms
Aerial photography	Acquisition of imagery of the ground taken from an airborne platform
GPS	Global Positioning System-acquiring real-time location information from a series of satellites in Earth's orbit
Geospatial data	aka spatial data, location-based data. Items that are tied to a specific real-world location
Non-spatial data	data that is not directly linked to a spatial location
Google Earth	a freely available virtual globe program first released in 2005
virtual globe	any software program that provides an interactive 3D map of Earth
The study of geography is...	why things are where they are
Geospatial technology includes...	GPS, GIS, remote sensing
True or false...Remote sensing images are typically "snapshots."	True
Aerial photography is from ________, satellite imagery is from _________.	Planes, satellites
True or false...geospatial dada and nonspatial data can be linked in useful ways.	True
True or false...environmental conditions can be monitored with remote sensing.	True
Homeland security GIS applications include...	Emergency evacuation plans, smoke plume modeling, and disaster mitigation and recovery efforts
Urban planners deal with...	waste water, green space, traffic, roads, and zoning
What is the goal of GPS?	Acquiring real-time location info from a series of satellites
True or false...the US Dept of Labor believes that geospatial technology is an enormous growth area likely to generate many new jobs.	True
Example of non-spatial data...	list of business names for a delivery truck to visit
True or false...images pulled from Google Earth are continuous.	False
True or false...geospatial data is location--based.	True
How does OCEARCH use geospatial technology?	GPS-used to pinpoint location GIS-uses pings to create other info, like shark path over period of time
Thoughts on volunteered geographic data...	If there was extensive training provided to members of the public, and if error margins are included in the data, it might be okay to trust it. Good for rescue efforts because it's a time sensitive situation and large amounts of data need to be processed.
Datum	a reference surface of Earth (model of Earth)
Ellipsoid	model of oblong, rounded shape of Earth. Larger at the center than at its poles
Geoid	Model of Earth using mean sea level as a base
Geodesy	the science of measuring Earth's shape
NAD27	North American Datum of 1927. Developed for measurements of the US and N. America. Center point = Meades Ranch, Kansas.
NAD83	North American Datum of 1983. Developed by the National Geodetic Survey (w/ Canadian agencies) and is used as the datum for much data for the US and N. America.
WGS84	World Geodetic System of 1984. Developed by the US Dept of Defense.
Datum transformation	Changing measurements from one datum to measurements in another datum. Computation process, standard in many geospatial software packages.
Geographic coordinate system	Global reference system for determining the exact position of a point on Earth using global latitude and longitude measurements
Latitude	Parallel to the Equator, run east-to-west around the globe. There are north and south latitudes.
Equator	line of latitude at Earth's center, 0 degree mark
Longitudes	Aka meridians, perpendicular to the Equator and run north-to-south from the North Pole to the South Pole. East and west longitudes.
Prime Meridian	Runs through Royal Observatory in Greenwich, England. 0 degrees
DMS	Degrees, minutes, and seconds. Degree=60 minutes, Minute=60 seconds.
DD	Decimal degrees. The fractional decimal equivalent to coordinates found using degrees, minutes, and seconds.
Great circle distance	The shortest distance between two points on a spherical surface
Time zones	method of measuring time around the world, created by dividing the world into subdivision of longitude and relating the time in that subdivision to the time in Greenwich, England
International Date Line	Line of longitude that uses the 180th meridian as a basis. Marks division between 24 hour periods and divides one day from another, but it also bends to accommodate geography, political boundaries, convenience, islands...doesn't strictly follow 180th meridian.
Map projection	translation of coordinates and locations from their places in the real world to a flat surface. 3D Earth to 2D surface
Mercator projection	keeps shapes of areas intact, sizes very distorted
Lambert conformal conic	?
Transverse Mercator	?
UTM	Universal Transverse Mercator. The grid system on locating coordinates across the globe
UTM Zone	One of the 60 divisions of the world set up by the UTM system, each zone being 6 degrees of longitude wide
easting	a measurement of so many units easy (or west) of some principal meridian
northing	a measurement of so many units north (or south) of a baseline. In the southern hemisphere, take measurement in meters as a negative value, then add 10,000,000 meters.
false northing	a measurement made north (or south) of an imaginary line, used in measuring UTM northing in the southern hemisphere (to avoid negative values)
false easting	a measurement made east (or west) of an imaginary meridian set up for a particular zone (based on an imaginary central meridian in each UTM zone)
USNG	United States National Grid. A grid system of identifying locations in the United States. Northing, easting, and zone information all written in a single string.
SPCS	State Plane Coordinate System. Grid-based system for determining coordinates of locations within the United States. Developed in 1930s, before computers. Used for city and county data and measurements.
SPCS zones	one of the divisions of the US set up by the SPCS. Zones are formed by following state or county boundaries.
A reference surface or model of the Earth, used for plotting locations across the globe, is called a...	datum
True or false: Lines of latitude run in an east-to-west direction around the globe.	True
Commonly used datums	NAD27, WGS84, NAD83
In a Mercator projection, _______ remains intact but _______ can be grossly distorted.	shapes, sizes
True or false: Measurements made from one datum are unlikely to precisely match the measurements made from another datum	True
True or false: A false easting is a measurement made east or west of an imaginary meridian set up for a particular zone in the UTM system	True
Which US state is composed of more than one SPCS zone?	Texas
In general, GSC measurements are made in...	DMS
True or false: One datum is used for all measurements of Earth's locations	False
True or false: In the UTM system, each UTM zone has its own central meridian	True
When making measurements on a sphere, the distance between two points is referred to as the...	great circle distance
True or false: Earth is perfectly rounded.	False
Which datum is used by the Global Positioning System?	WGS84
A map's distortion is minimized at...	the point of tangency
SPCS is a coordinate system for...	the United States
Negative values can be used when making measurements _______ of the Equator and _____ of the Prime Meridian	south, west
One degree = __ minutes, one minute = __ seconds	60, 60
True or false: All flat maps have some distortion built into them.	True
Reproject	Changing a dataset from one map projection (or measurement system) to another. Translates coordinates, map projections, and measurements
Spatial reference	The use of a real-world coordinate system for identifying locations
Georeferencing	A process whereby spatial referencing is given to data without it. Aligning an unreferenced dataset with one that has spatial reference information
Control points	Point locations where the coordinates are known. Those are used in aligning the unreferenced image to the source. Ground control points or GCP
RMSE	Root mean square error. An error measure used in determining the accuracy of the overall transformation of the unreferenced data; how well now-referenced data matches source. Lower=better.
Which type of transformation entails pulling the image, often at a slant?	Skewing
True or false: In general, the higher the RMSE, the better the match between the unreferenced data and the source data.	False
On an older printed map, the zero reference point is usually found in the...	lower left corner
The common areas that the unreferenced data to spatially referenced data are called...	control points
The process of transforming all your data sets to match one spatial referencing measurement system is called...	reprojection
True or false: When selecting control points, its best to cluster them near the center of the map.	False
True or false: In the georeferencing process, it is best if the source dsata uses a similar projection to the unreferenced data.	True
Which type of transformation entails altering the location and placement of a map?	Translation
If you use a photo scanner to scan an old map, then open the image in a GIS with data for the same location, the image will...	not match up because it lacks any spatial reference
Assuming your control points are well chose, adding more points should...	improve the fit between the unreferenced data and the source
True or false: Georeferencing can be used for non-map data, including unreferenced drawing and plans	True
In georeferencing, what is the minimum number of control points required to fit an unreferenced image to the source?	3
True or false: In general, it is quite easy to overlay maps created from different datums.	False
All of the following are poor control-point selection choices EXCEPT...	the intersection of roads
GPS	Global Positioning System. A technology using signals broadcast from satellites for navigation and position determination on Earth
NAVSTAR GPS	the United States Global Positioning System
GNSS	the global navigation satellite system, an overall term for the tehchnologies that use signals from satellites to find locations on Earth's surface
3 components of GPS	space segment, control segment, user segment
Space segment	consists of satellites and the signals they broadcast from space.
Constellation	the full complement of satellites comprising a GNSS. Designed to allows a person to be able to receive enough GPS signals to find their location anywhere on the planet. 24 satellite minimum
Control segment	consists of the control stations that monitor the signals from the GPS satellites. They collect satellite data and transmit it to the master control station at Schriever Air Force Base
User segment	consists of the GPS receivers on the ground that pick up signals from the satellites
Channels	the number of satellite signals a GPS unit can receive
Single frequency	a GPS receiver that can pick up only the L1 frequency
Dual frequency	a GPS receiver that can pick up both the L1 and L2 frequency
almanac	data concerning the status of a GPS satellite, which is included in the information being transmitted by the satellite
ephemeris	data referring to the GPS satellite's position in orbit
C/A code	coarse acquisition code. The digital code broadcast on the L1 frequency, which is accessible by all GPS receivers
P Code	Precise code. The digital code broadcast on the L1 and L2 frequencies, which is accessible by the military
Y Code	encrypted version of the P code
Pseudorange	the calculated distance between a GPS satellite and a GPS receiver
Trilateration	Finding a location in relation to three other points of reference
3D trilateration	finding a location on Earth's surface in relation to the position of 3 satellites
Selective availability	the intentional degradation of the timing and position information transmitted by a GPS satellite; made C/A signal less accurate, so enemies couldn't use GPS against the US military. Introduced two errors: delta error (incorrect clock timing info) and epsilon error (incorrect satellite ephemeris information). Turned off in 2000.
PDOP	the position dilution of precision. It describes the amount of error due to the geometric position of the GPS satellites
multipath	an error caused by a delay in the signal due to reflecting from surfaces before reaching the receiver
DGPS	differential GPS. A method using a ground-based correction in addition to the satellite signals in position determination
NDGPS	National Differential GPS. Consists of ground-based DGPS locations around the US. Operated by the US DOT.
CORS	Continuously Operating Reference Stations. A system operated by the National Geodetic Survey to provide a ground-based method of obtaining more accurate GPS positioning
SBAS	Satellite based augmentation system-a method of using correction information sent from an additional satellite to improve GPS position determination
WAAS	Wide Area Augmentation System. A satellite based augmentation system that covers the US and other portions of N. America. Developed by the Federal Aviation Administration to obtain more accurate position info for aircraft
GLONASS	the former USSR's (now Russia's) GNSS
Galileo	the European Union's GNSS, currently in development
Compass	China's GNSS, currently in development. AKA Beidou-2
EGNOS	an SBAS (Satellite Based Augmentation System) that covers Europe
MSAS	an SBAS that covers Japan and nearby regions
True or false: GPS is a "public domain" good that is free and available to everyone worldwide	True
A technology that uses signals broadcast from satellites to determine position and navigation on Earth is ______	GNSS
What is the minimum # of satellites needed for a constellation?	24
The control segment of GPS is composed of a series of __________.	Ground stations
GPS satellites make ___ orbits around the Earth every day.	2
The signals containing info about the satellite's status, orbit, and location are collectively referred to as the ________.	Almanac
Which of the following does not describe an attempt to make GPS more accurate?	PDOP
Ephemeris errors typically introduce ______ or so of error	2 meters
The European Union's version of GNSS is known as _______.	Galileo
Transmission time (t) x speed of light (c) =	pseudorange between receiver and satellite
The original developer of NAVSTAR GPS was which county's Dept. of Defense?	the USA
Which of the following is NOT one of the 3 main/cooperating elements of GNSS?	position segment...but not important. Just know control segment, ground segment, and user segment
How many points of reference (satellites) are required for you to find your exact location on Earth?	3
In which year was the first GPS satellite launched?	1978
Which of the following is the most highly encrypted and secure?	Y code
True or false: Users of GPS can send info back to satellites.	False

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