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Description
Flashcards by Shea Poage, updated more than 1 year ago
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Created by Shea Poage
about 8 years ago
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| Question | Answer |
| 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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