Geography Quiz 2

Please order the wavelengths of the spectral bands in an ascending order (short-->long) to form the electromagnetic spectrum

Blue, green, near infrared, mid infrared, thermal infrared

What is relief displacement?

On vertical air photos, the scale of the photo will most likely be distorted radially away from its center. Tall objects (such as steep cliffs, towers, and buildings) have a tendency to "bend" outward from the center point toward the edges of the photo. geometric center of the photo is called THE principal point.

How can GPS' navigation function be used in the public sector (government, military)?

Originally conceived and developed by the US military, used to help their aircraft and ships navigate. They also used it to guide weapons (missiles) to precise targets or to deliver humanitarian supplies

What are some sources of errors in GPS?

Satellite clocks, Selective availability (SA), Atmospheric conditions, and Multipath errors

What is spectral resolution?

the number of spectral bands -- portions of the electromagnetic spectrum (blue, green, red) -- that a sensor can collect energy in

What is image interpretation?

the process of extracting qualitative and quantitative information from a photo or image using human knowledge or experiences.

What is temporal resolution?

the revisit period of a satellite sensor for a specific location. It is the length of time for a satellite to return to the exact same area at the same viewing angle

What is a pixel in a remote sensing image?

tiny uniform regions that make up a remote sensing image, each with its own unique value indicating the amount of energy being measured by the sensor

IKONOS has lower spatial resolution compared with Quick-bird. (true or false)

true

Vegetation reflects most of the near infrared radiation from the sun. (true or false)

true

How do you use shapes in interpretation?

Shape can be a very distinctive clue in image interpretation. For example, agricultural fields and man-made features (e.g., urban or agricultural features) tend to have straight lines, sharp angles, and regular forms while natural features (e.g., forest edges) are generally more irregular.

How does selective availability affect GPS accuracy?

When SA was active, civilian GPS receivers could only get position accuracy within 100 meters. This, naturally, limited GPS applications in the civilian sector - who wants to try to land an airplane using GPS when the runway's location could be 100 meters off?

Which of the following is NOT a Suomi NPP instrument? a) ATMS b) VIIRS c) MODIS d) OMPS

c) MODIS

What are some other global satellite navigation systems (GNSS)?

* Galileo: the European Union's version of GPS, which, when completed, is projected to have a constellation of 30 satellites and operate in a similar fashion to GPS * GLONASS was the name of the USSR's counterpart to GPS and operated in a similar fashion. It provides an alternative to Global Positioning System (GPS) and is the only alternative navigational system in operation with global coverage and of comparable precision *COMPASS (BeiDou-2): China's version of GPS currently under construction. The system will be a constellation of 35 satellites

How can GPS' locating function be used in environmental research?

* Measuring the movement of volcanoes and glaciers. * Measuring the growth of mountains. * Measuring the location of icebergs - this is very valuable for ship captains to avoid possible disasters. * Storing the location of where you were - most GPS receivers on the market will allow you to record a certain location. This allows you to find these points again with minimal effort and is useful in hard-to-navigate areas such as dense forest * Give alerts sooner about tsunamis and earthquakes

What is the difference between geostationary orbit, polar orbit, and sun-synchronous orbit?

* geostationary orbit: a satellite travels at the same speed as the Earth's rotation, which means it monitors the same place on Earth all the time (Figure 1). Many weather satellites are in geostationary orbit so they can continuously collect information about the same area. *polar orbit: satellites pass over both poles of the Earth several times a day. *Sun-synchronous orbit is a type of near-polar orbit, where the satellite always passes over the same location at the same local time. Most remote sensing satellites are in sun-synchronous orbits. This way the satellites always capture images of the Earth's surface under similar solar-illumination conditions; this makes it easier to compare images taken from multiple passes

What are the differences between vertical, low oblique, and high oblique aerial photos?

* vertical photos are shot straight down from a hole in the belly of the airplane * Low Oblique photographs are typically taken from 300-1,000 feet above the ground, at a 5-30 degree angle, through the open door of a helicopter. provides more details about the target objects to be viewed * High Oblique photographs are taken from 8,000-13,000 feet above the ground from an airplane, at a 30-60 degree angle, from an open window of the airplane. provides more ground area can be covered on a single photo

Looking at your neighborhood what things would you pair with the element of image interpretation?

*Houses: pattern (regularly-spaced) *Walkways leading to houses: size, shape, and association *Cars in a parking lot: pattern, shape, association *Parking spaces in a parking lot: association *Factory building on the west side of the photo: size (large size buildings), association (large parking lot)

Compare these three: panchromatic sensors, multi-spectral sensors, hyper-spectral sensors.

*Panchromatic sensor: a sensor measuring the visible portion of the spectrum and treating the entire 0.4 to 0.7 micrometer range as a single band. *Multispectral sensor: a sensor that measures several broad bands. For example, we can divide the visible and near-infrared portions of the spectrum into four bands: blue, green, red and a near-infrared band. *Hyperspectral sensor: a sensor that measures many narrow contiguous bands. A hyperspectral sensor can sense over 200 bands.

How does a GPS receiver obtain its position in three steps?

1) Satellites send signals containing location and time to the GPS receiver. 2) The GPS receiver searches and obtains signals from at least three satellites. The more satellites it finds, the higher accuracy it can achieve. 3) The GPS receiver a) calculates its distance to the satellites, and b) determines its location using the method of "trilateration".

Briefly describe the process of satellite remote sensing.

1. find energy source of illumination (radiation) 2. radiation passes through the atmosphere 3. energy interacts with target (location being looked at) 4. sensor on satellite collects and records the electromagnetic radiation 5. energy recorded by the sensor is transmitted to a receiving station where data is processed into an image 6. image is interpreted, visually and/or digitally, to extract information about the target. 7. use the information extracted from the imagery to find new information or to solve a particular problem.

What does the GPS constellation consist of?

24 satellites, all satellites are divided into 6 orbital planes. There are 4 satellites on each orbital plane.

What is the minimum number of GPS satellites you receive information form in order to get a fix on your horizontal position?

3 satellites

How many wavelengths can the Landsat 7 satellite sense simultaneously?

7

What is the space segment of GPS?

A constellation of satellites orbiting the Earth, each emitting a radio signal about every second. They contain information about the position and precise time.

What is the atomic clock?

A timekeeping device that uses an atom's electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum as a frequency standard for its timekeeping element. The most accurate way to keep time, it is used in GPS to ensure accurate position.

What are some trade-offs between spatial, temporal, and spectral resolution?

As a result remote sensors are always designed with trade-offs. Figure 6 shows the spatial and temporal resolution of several current satellite remote sensing systems. You can see that some sensors have high temporal resolution, but low spatial resolution, like GOES, AVHRR, and MODIS. Some of them have low temporal resolution and high spatial resolution. There are also some with medium spectral, temporal, and spatial resolution, like Landsat and SPOT. However there are none with high resolutions in all three aspects.

What are common platforms used in aerial photography?

Commonly used for military

How does a GPS receiver calculate its distance to the satellites?

Distance= time delay (T1- T) * speed of lights (180,000 mi/sec)

What is the EOS mission? Describe the applications of MODIS.

Earth Observing System (EOS), which is a constellation of satellites that measure the clouds, oceans, vegetation, ice, and atmosphere of the Earth. EOS has three flagship satellites, Aqua, Terra and Aura, which are equipped with fifteen sensors. MODIS is carried on both the Terra and Aqua satellites and can image most of the globe in one day, with complete global coverage in two days. With very high temporal resolution, MODIS allows scientists to quickly assess changes in landscapes, such as sea surface temperature, snow cover, global forest, and active large-scale fires.

In a long wavelength, waves occur more frequently (true or false)

Flase, In a long wavelength, wave has low frequency and occur less frequently

How is GPS data used in mapping?

GPS can also be used to create maps by recording a series of locations as well as useful information. This function is used by scientists to collect field data, as well as by industrial and governmental bodies in making geospatial policy.

What is the control segment of GPS?

GPS represents a series of worldwide ground control stations that track and monitor the signals being transmitted by the satellites. These control stations are spread out to enable continuous monitoring of the satellites.

How is GPS' timing function used?

GPS satellites carry an atomic clock that contributes very precise time data to GPS signals. Communication systems, electrical power grids, and financial networks all rely on precision timing for synchronization and operational efficiency. With the GPS timing function, we can all synchronize our watches and make sure international events are actually happening at the same time.

How do you use tones/colors in interpretation?

Generally, tone is the fundamental element for distinguishing between different targets or features. Color is more convenient for the identification of object details.

What is GPS?

Global Positioning System. A space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites (3 satellites for 2D and, 4 satellites for 3D)

How do you know if a satellite has a high, medium, or low temporal resolution?

If a satellite needs less than 3 days to revisit the same place, we would say it has high temporal resolution. If a satellite needs 4-16 days to revisit the same place, it has medium temporal resolution; if it takes more than 16 days to revisit the same place, it has low temporal resolution.

What is satellite imagery?

Images taken from sensors mounted on satellites.

How do low spatial resolution images compare to high spatial resolution images?

Images where only large features are distinguishable have low resolution, while in high resolution images, small objects can be detected. Generally speaking, the higher the resolution of an image, the more detail it contains.

What is aerial photography?

Images/photos taken from cameras/sensors mounted on aircraft.

What are the electromagnetic wavelengths displayed in color infrared aerial photos?

Infrared energy is invisible to our eyes, but is reflected very well by green, healthy vegetation. In CIR photos near-infrared (NIR) energy is displayed in the color red, red light is displayed with the color green, and green light is displayed in the color blue.

What is Wide Area Augmentation System (WAAS)?

Is a satellite-based, new "real-time" DGPS correction method, developed by the Federal Aviation Administration (FAA) to obtain more accurate position information for aircraft. Operates through a series of 25 base stations spread throughout the United States that collect and monitor the signals sent by the GPS satellites. These base stations calculate position correction information (similar to the operation of DGPS) and relay correction information to the master control station. Master control station will then transmit this correction to a WAAS satellite.

How is DGPS different from normal GPS?

It uses two receivers, one at a known location and one at an unknown location

What are some examples of using Landsat images to monitor Earth's environmental changes? (hint: forest, agriculture, urban areas, ice, natural disasters)

Landsat images of the Amazon rainforest. The left was taken in 1975, while the right one was taken in 2012. These two images highlight dramatic change in forest: deforestation taking on a "fishbone" pattern following major roads. Landsat data has also been used in wildfire monitoring. Intense wildfires usually happen in conifer forests, though they occur infrequently. Fire returns nutrients to the soil and replaces old tree stands and ground debris with young forest. Landsat can track the development of the young forest.

MODIS has _____ spatial resolution and _____ temporal resolution.

MODIS has moderate spatial resolution (500m-1km) and very high temporal resolution with a revisit time of only 2 days. (moderate, high)

How do multipath errors affect GPS accuracy?

Multipath errors occur when GPS satellite signals reflect off surfaces, such as trees or buildings before they reach the GPS receiver. These reflections delay the signal and cause inaccuracies.

Are aerial photographs maps? Why?

NO. Maps are representational drawings of Earth's features while images are actual pictures of the Earth. Maps have uniform scale, which means that the map scale at any location on the map is the same.

What are the five most basic functions of GPS?

Navigation, location, timing, mapping, and tracking

What is the electromagnetic spectrum?

Of the entire EM spectrum, visible light (the part we can see) is only a tiny portion. Sensors used in remote sensing are much more sensitive than our eyes. They can detect EM energy in both the visible and non-visible areas of the spectrum.

What is an orthophoto? How is it produced?

Orthophotos are vertical aerial photographs which have been geometrically "corrected". The rectification process removes relief displacement. An orthophoto is a uniform-scale photograph. Since an orthophoto has a uniform scale, it is possible to measure the ground distance on it like you would on a map. An orthophoto can also serve as a base map onto which other map information can be overlaid.

What is the difference between passive and active remote sensing?

Passive remote sensing measures energy that comes from an external source such as sun or the target itself.Active remote sensing, on the other hand, provides its own source for illumination.

How much is the overlap along flight lines and across adjacent flight lines? Why is this overlap needed?

Photos are taken along straight flight lines with 60% to 80% overlap, that is each individual photo overlaps its neighbor by 60-80%. Typically more than one flight line is required to cover the area to be mapped, and adjacent flight lines get a 20%-30% side overlap to ensure no gaps in the coverage. This overlap allows for 3D viewing of aerial photographs using the principle of stereopsis.

Name a few high spatial resolution commercial satellites and explain their applications.

QuickBird: data contributes to mapping, agricultural and urban planning, weather research, and military surveillance. WorldView-1, WorldView-2, IKONOS, GeoEye-1, and WorldView-3: Many of their pictures are seen on google earth. High resolution images such as these can be used to produce map images that clearly show smaller features such as cars and trees; these images are useful for natural resource management, urban planning, and emergency response.

How does 3D trilateration work in GPS?

Rather than locating yourself relative to three other points on a map, the GPS receiver is finding its distances relative to three satellites. Also, since a position on a 3D Earth is being found with reference to positions surrounding it, a spherical distance is calculated rather than a flat circular distance.

In a color infrared photo, near-infrared signal is displayed in what chanel?

Red

How do you define remote sensing and satellite remote sensing?

Remote sensing is the science and technology of getting information about objects without directly making contact with it, usually from an aircraft or satellite. Satellite remote sensing are sensors that are located on satellites that capture images of earths surface

What are some privacy concerns of GPS technology?

Rental car companies can track customers with GPS and impose fines if they exceeded 79 mph. This would violate the privacy of customers, since the car companies know where they are going and where they have been. As GPS technology is combined with smartphones, it can be used to track employees, children, and parolees. How to keep a balance between GPS's capability and user privacy is a big issue.

How do you use sites/association in interpretation?

Site represents the location characteristics of a feature, while association means relating a feature to other nearby features. Sometimes objects that are difficult to identify on their own can be understood from their association with objects that are more easily identified. For example, commercial properties may be associated close to major transportation routes, whereas residential areas would be associated with schools, playgrounds, and sports fields.

How do you use sizes in interpretation?

Size is information about the length and width of objects in the image. The relative size of objects in an image can offer good clues to what they are.

What are the three components of GPS?

Space, Control, and User segment

What is the GEOS system? What is it used for?

The GOES series of satellites is the primary weather observation platform for the United States. The GOES system, operated by the United States National Environmental Satellite, Data, and Information Service (NESDIS), supports weather forecasting, severe storm tracking, and meteorology research.

What is the Landsat Program?

The Landsat Program is a series of Earth-observing satellite missions jointly managed by NASA and the U.S. Geological Survey (USGS). ...Through four decades, Landsat satellites have taken specialized measurements of Earth's continents and surrounding coastal regions, enabling people to study many aspects of our planet and to evaluate the dynamic changes caused by both natural processes and human practices. The long record of Landsat spectral information is a historical archive unmatched in quality, detail, coverage, and length.

What are the eight elements used in image interpretation? What do they mean?

Tone/color -- lightness/darkness/color of an object Texture -- coarse or fine, such as in a corn field (distinct rows) vs. wheat field (closely-grown plants) Shape -- square, circular, irregular Size -- small to large, especially compared to known objects Shadow -- objects like buildings and trees cast shadows that indicate vertical height and shape Pattern -- many similar objects may be scattered on the landscape, such as oil wells Site -- the characteristics of the location; for example, don't expect a wetland to be in downtown Chicago Association -- an object's relation to other known objects -- for example, a building at a freeway off-ramp may be a gas station based on its relative location

In a project, scientists made a map indicating the melting of Greenland glaciers based on the data from 50 GPS stations planted along the Greenland coast. What functions of GPS were used in this research?

Tracking and mapping

What is Suomi-NPP? How many sensors does Suomi NPP carry? What are some examples of the application of these sensors?

The Suomi National Polar-orbiting Partnership (NPP) is the first satellite launched as part of a next-generation satellite system that will succeed the Earth Observation System (EOS). It orbits the Earth about 14 times a day and images almost the entire surface. Every day it crosses the equator at about 1:30 pm local time. This makes it a high-temporal resolution satellite. There are five sensors aboard Suomi NPP: *Advanced Technology Microwave Sounder (ATMS): Measures the microwave radiation of the sun reflected by objects on the Earth's surface. Retrieves profiles of atmospheric temperature and moisture for weather forecasting. *Visible Infrared Imaging Radiometer Suite (VIIRS): A sensor that collects visible and infrared imagery of the land, atmosphere, cryosphere, and oceans.Used to measure cloud and aerosol properties, ocean color, sea and land surface temperature, ice motion and temperature, fires, and Earth's albedo. *Cross-track Infrared Soundear (CrIS): Provides three-dimensional temperature, pressure, and moisture profiles of the atmosphere. *Ozone Mapping Profiler Suite (OMPS): Measures the global distribution of the total atmospheric ozone column on a daily basis. *Clouds and the Earth's Radiant Energy System (CERES): A three-channel sensor measuring the solar-reflected and Earth-emitted radiation from the top of the atmosphere to the surface. Important for understanding climate change.

How do atmospheric conditions affect GPS accuracy?

The atmosphere is one of the largest sources of error due to atmospheric refraction. The satellites send signals to GPS receivers, but particles in the atmosphere can alter the speed of signal and cause delays. This causes inaccurate measurements of the time delay.

Why is the Landsat Program a unique remote sensing system? (hint: the long-term historical imagery and continuous observation missions)

The data from the Landsat spacecraft constitute the longest record of the Earth's continental surfaces as seen from space. It is a record unmatched in quality, detail, coverage, and value for global change research and has applications in agriculture, cartography, geology, forestry, regional planning, surveillance and education.

How can you tell if a satellite has high, medium, or low spectral resolution?

The finer the spectral resolution, the narrower the wavelength ranges for a particular channel or band. High spectral resolution: ~200 bands Medium spectral resolution: 3~15 bands Low spectral resolution: ~3 bands

How is GPS used in tracking?

Tracking is a way of monitoring people and things such as packages, or moving vehicles. This has been used along with wireless communications to keep track of criminals and parolees. A convict agrees to keep a GPS receiver and transmitting device with him at all times. If he goes where he's not allowed, the authorities will be notified. This can also be used to track animals. In transportation, GPS is also used to monitor traffic flow by tracking taxis and personal cars.

Which of the following is NOT true about satellites? a) They are constantly orbiting the Earth b) They can image much larger areas than single aerial photos can c) They are restricted to geographic boundaries, much the same way that aircraft are d) They are, in general, superior to aircraft in terms of their ability to capture images on Earth

c) they are restricted to geographic boundaries much the same way aircrafts are

What are the differences between panchromatic, true color, and color infrared aerial photos?

The most obvious difference between true color and color infrared photos is that in color infrared photos vegetation appears red * Red tones in color infrared aerial photographs are always associated with live vegetation and the lightness or intensity of the red color can tell you a lot about the vegetation itself; its density, health and how vigorously it is growing. Dead vegetation will appear as various shades of tan, while vivid, healthy green canopies appear bright red. * True color photographs show the colors visible to the human eye * Panchromatic photographs (black and white photographs) are sensitive to light of all visible colors. They generally reflect how bright the surface is. Therefore, healthy deciduous vegetation is typically light (nearly white), roads are dark, and water bodies are usually black.

What is navigation?

The process of getting from one location to another based on transportation information

What is remote sensing?

The process of obtaining information ("sensing") without physical contact ("remote"). In geography and environmental sciences, remote sensing refers to technologies that measure objects on Earth surface through sensors onboard aircraft or satellites

What is trilateration?

The process used by GPS to determine the location of a receiver by measuring the distances to three or more satellites.

What is the user segment of GPS?

The receiver picks up and processes the incoming signals sent by the satellites. GPS devices that receive its signals, are your smartphone, handheld GPS, or car navigation system

How do you use textures in interpretation?

The visual impression of smoothness or roughness of an area can be a valuable clue in image interpretation. For example water bodies are typically fine textured, while grass is medium (homogeneous grassland exhibits a smooth texture), and brush is rough (e.g., coniferous forests usually show a coarse texture), although there are always exceptions.

How do you use patterns in interpretation?

This is most apparent for man-made features: city street grids, airport runways, agricultural fields, etc. Patterns in the natural environment may also be noticeable, for example bedrock fractures, drainage networks, etc. Man-made features such as cities tend to have very regular patterns, while natural features do not have regular patterns.

How do satellite clocks affect GPS accuracy?

We need to know the time when a signal was sent from the satellite and the time when the signal reached to the receiver. Therefore we need to synchronize the receiver's clock with the satellite's clock. However inevitable inaccuracies in determining time means there will be an error of about 1.5-3.6m in determining the receiver's location.

What three things can happen when some form of radiation interacts with the target on the earth's surface?

Transmittance occurs when energy simply passes through a surface. Think of light passing through a windshield of a car. Absorption occurs when energy is trapped and held by a target. Reflection: Most of the radiation not absorbed is reflected back into the atmosphere, some of it towards the satellite. This upwelling radiation undergoes another round of scattering and absorption as it passes through the atmosphere before finally being detected and measured by the sensor.

How is the spectral signature of trees different from that of water?

Trees and Leaves: A chemical compound in leaves called chlorophyll strongly absorbs radiation in the red and blue wavelengths of visible light, but reflects green wavelengths. Healthy leaves enhances the reflection of near infrared radiation Water: water reflects much less radiation than other objects; this means water always looks dark in remote sensing images. Longer wavelength (i.e. red and infrared) radiation is absorbed more by water than shorter visible wavelengths

How do you determine your location on a map using 2D trilateration?

Trilateration in two dimensions is commonly used when plotting a location on a map. It is the process of determining absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangles

How does Differential GPS (DGPS) work?

Uses a series of base stations at specific locations on the ground to provide a correction for GPS position determination. When you are using DGPS, your receiver is picking up the usual four satellite signals plus an additional correction from a nearby base station

What wavelengths in the electromagnetic spectrum are commonly used in remote sensing?

Visible Light: Blue, green, and red are the primary visible wavelengths, and most remote sensors are equipped to detect energy at these wavelengths. Visible wavelengths are useful in remote sensing to identify different objects. Infrared: Near IR is particularly sensitive to green vegetation. Therefore, most remote sensors on satellites can measure near-infrared radiation, which lets them monitor the health of forests, crops, and other vegetation. Thermal/far IR is sensitive to heat. Objects that have a temperature above absolute zero (-273 C) emit far IR radiation. Therefore, all features in the landscape, such as vegetation, soil, rock, water, and people, emit thermal infrared radiation. In this way, remote sensing can detect forest fires, snow, and urban areas by measuring their heat. Microwave: This covers the longest wavelengths used for remote sensing. In remote sensing, microwave radiation is used to measure water and ozone content in the atmosphere, to sense soil moisture, and to map sea ice and pollutants such as oil slicks.

What are some advantages of remote sensing as a tool to collect information about Earth's surface?

With the aid of remote sensing and Geographic Information System (GIS), we can now collect global topographic information for both land and ocean over days instead of years. Compared to traditional data collecting methods, remote sensing has the following advantages: 1. It is capable of rapidly acquiring up-to-date information over a large geographical area. 2. It provides frequent and repetitive looks of the same area. 3. It is cheap with less labor input. 4. It provides data from remote and inaccessible regions, like deep inside deserts. 5. The observations of remote sensing are objective.

What is spatial resolution?

a measure of the smallest object or area on the ground that can be detected by the sensor.

What are the different types of orbits used by remote sensing satellites?

geostationary orbit, polar orbit, and sun-synchronous orbit.

What is the spectral signature?

he properties of an object as described by its absorption and reflection properties at different wavelengths

How do you use shadows in interpretation?

it can provide an idea of the profile and relative height of a feature, which makes it easier to identify. Trees, buildings, bridges and towers are examples of features that cast distinctive shadows.

What is remote sensing is actually capturing?

reflected light