GEOG 170 Final Review

Geospatial Technology

Geospatial Technology

Tools used for location-based data.

Geographic Information System (GIS)

A computer-based technology for storage, analysis, and management of location-based data.

Remote Sensing (RS)

Technology used to acquire imagery of the earth's surface through satellites or aircraft.

Global Positioning System (GPS)

Technology that acquires real-time location information from satellites in Earth’s orbit.

Information

Interpretation of data with the aid of analysis or other tools.

Geographic/geospatial information

Information with a location (x,y) component and associated attributes.

Map

Spatial representation of geographic information presented graphically.

Reference map

Emphasizes the location of spatial phenomena to aid discovery of locations.

Thematic map

Specially designed to show a particular theme connected with a specific geographic area.

Persuasive map

Intended to convey an idea rather than communicate geographic information.

Decimal Degrees

A method of expressing coordinates using a decimal format, obtained by converting degrees, minutes, and seconds into a single decimal number.

Latitude

The angular distance measured in degrees north or south from the Equator, with values ranging from 0° at the Equator to 90° at the poles.

Longitude

The angular distance measured in degrees east or west from the Prime Meridian, with values ranging from 0° at the Prime Meridian to 180° east or west.

Great Circle

The shortest path between two points on a sphere, such as the Earth, formed by a plane passing through the center of the sphere and the two points.

Ellipsoid/Spheroid

A mathematical model representing the Earth's shape, slightly flattened at the poles and bulging at the equator, used to approximate the Earth's surface.

Geodetic Datums

Reference systems defining the shape and size of the Earth, including the ellipsoid, base point coordinates, and north direction, used for mapping and positioning.

Map Projection

A mathematical method of transforming the Earth's curved surface onto a flat map, preserving certain properties like shape, area, distance, or direction.

Tissot’s Indicatrix

Circles used to visualize distortions caused by map projections, showing changes in area and shape before and after projection.

Cartesian Coordinate System

A two-dimensional system using x and y axes to represent locations on a flat surface, simplifying measurements and analysis compared to geographic coordinates.

Universal Transverse Mercator (UTM) Coordinate System

A global projected coordinate system dividing the Earth into zones, each with a central meridian, used for precise location referencing.

UTM Zones

Numbered from 1 to 60, each covering a six-degree band of longitude, starting from 180° longitude at the International Date Line and proceeding eastward.

Easting

The east-west x-coordinate in a UTM coordinate system, with a false easting value of 500,000 m added to ensure no negative values.

Northing

The north-south y-coordinate in a projected coordinate system, with a false northing of 10,000,000 m in the southern hemisphere to keep all values positive.

UTM Coordinates

Typically consist of a six-digit easting value, a seven-digit northing value, and a zone number with a hemisphere indicator.

State Plane Coordinate (SPC)

A system with 124 geographic zones designed for specific regions in the U.S., with boundaries following county lines and specific projections for each zone.

Map Scale

Expresses the relationship between distances on a map and their corresponding ground distances, essential for converting measurements on a map to ground units.

Representative fraction

The ratio between map and ground distances, expressed as a fraction like 1:63,360.

Verbal scale

A type of map scale that uses words to describe the ratio between the map's scale and the real world, often using familiar units.

Scale bar

A graphic element on a map that visually represents the scale using a bar or line divided into segments.

Large scale vs

Large scale maps show a small area with more details, while small scale maps show a large area with fewer details.

Transitioning between scales

In paper maps, the scale is fixed, while in computer-based maps, the scale is dynamic and changeable.

GLONASS

The USSR's counterpart to GPS, providing global coverage and precision, with a constellation of satellites similar to GPS.

Galileo

The European Union's satellite navigation system, aiming for 30 satellites and functionality akin to GPS.

COMPASS (BeiDou-2)

China's GPS alternative, a constellation of 35 satellites under construction.

Trilateration

GPS method using distances from at least three satellites to determine receiver location.

Differential GPS

Correction method using ground base stations to enhance GPS positional accuracy.

Navigation

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

Atomic clock

A timekeeping device that uses an atom's electronic transition frequency as a frequency standard for its timekeeping element, ensuring accurate positioning in GPS.

Locating

The function of GPS that provides accurate and precise location information under any weather conditions.

Timing

The function of GPS that brings precise time data to various applications, measured in nano seconds for synchronization in communication systems, power grids, and financial networks.

Mapping

The function of GPS used to create maps by recording locations and information, applied in collecting field data and making geospatial policy decisions.

Tracking

Monitoring people, packages, or vehicles using GPS technology, such as in tracking suspects, lost children, or pets for safety and security purposes.

Oblique aerial photograph

A photo taken at an angle where the camera axis is tilted away from vertical.

Low Oblique photograph

A photo taken from 300-1,000 feet above the ground at a 5-30 degree angle, often showing building facades without the roof.

High Oblique photograph

A photo taken from 8,000-13,000 feet above the ground at a 30-60 degree angle, showing larger areas but with less environmental detail.

Relief displacement

The effect where tall objects in photos bend outward from the center towards the edges, influenced by camera height and angle.

Orthophoto

A rectified aerial photo that removes relief displacement, providing a uniform scale for accurate measurements and map overlays.

Tone

The relative brightness or color of objects in an image.

Texture

The frequency of change and arrangement of tones in particular areas of an image.

Site

The location characteristics of an item in the image.

Association

The relation between an object and other nearby features in an image.

Remote Sensing

Obtaining information about objects or areas without direct physical contact.

Geostationary Orbit

Orbit where a satellite travels at the same speed as Earth's rotation, monitoring the same place.

Advantages of Remote Sensing

Rapid acquisition of up-to-date information over large areas, frequent looks of the same area, cost-effectiveness, access to remote regions, and objective observations.

Electromagnetic Spectrum

Range of all possible wavelengths of electromagnetic radiation.

Near Infrared

Wavelengths sensitive to green vegetation, used to monitor the health of forests and crops.

Thermal Infrared

Wavelengths used to detect heat emissions from objects like forest fires, snow, and urban areas.

Microwave

Longest wavelengths used for remote sensing, measuring water content, soil moisture, and mapping sea ice.

Passive Remote Sensing

Measures energy from external sources like the sun or the target itself.

Active Remote Sensing

Provides its own source of illumination, emitting radiation toward the target.

Spectral Signature

Unique absorption and reflection properties of objects at different wavelengths, used for identification in remote sensing images.

Pixels

Tiny uniform regions in a remote sensing image, each with a unique value indicating the amount of energy measured by the sensor.

Band

A range of wavelengths detected by a remote sensor, such as green band or near-infrared band.

Channel

The displayed color (red, green, or blue) on electronic screens, where different bands can be displayed in different channels in color composite images.

Spatial resolution

The measure of the smallest object or area on the ground that can be detected by a sensor, influencing the detail visible in an image.

Temporal resolution

The revisit period of a satellite sensor for a specific location, indicating how often the satellite returns to the same area.

Spectral resolution

Specifies the number of spectral bands that can be detected by the sensor, affecting the detail and color of the image produced.

Passive remote sensing

Technology where the sensor measures reflected EM energy from an external source like the sun.

Active remote sensing

Technology where the sensor provides its own energy source to illuminate the target and detect the reflected energy.

Transmittance

When an EM wave passes through an object without being absorbed or reflected.

Reflection

The process where EM energy is reflected back to the atmosphere instead of being absorbed or transmitted by the object.

Visible Infrared Imaging Radiometer Suite (VIIRS)

A sensor collecting visible and infrared imagery of the land, atmosphere, cryosphere, and oceans with high-spectral resolution and 9 bands in visible and near IR wavelengths, 8 bands in Mid-IR, and 4 bands in Long-IR.

Cross-track Infrared Sounder (CrIS)

A fourier transform spectrometer with 1,305 spectral channels in far infrared wavelengths providing three-dimensional temperature, pressure, and moisture profiles of the atmosphere for weather forecasting models and climate understanding.

Ozone Mapping Profiler Suite (OMPS)

Measures the global distribution of total atmospheric ozone column daily, enhancing the vertical structure understanding of ozone and its interactions with other gases in the atmosphere.

Clouds and the Earth's Radiant Energy System (CERES)

A three-channel sensor measuring solar-reflected and Earth-emitted radiation critical for understanding climate change.

Landsat Program

The longest continuous Earth-observation program providing medium resolution multispectral data of Earth's surface with applications in agriculture, cartography, and global change research.

Landsat Sensors

MSS, TM, ETM+, OLI, and TIRS are sensors used on Landsat satellites with varying spatial resolutions and spectral bands for Earth observation.

Landsat Data Applications

Valuable for agriculture, forestry, land use, water resources, and natural resource exploration, aiding in understanding changes in global environment and monitoring wildfires.

Geostationary Operational Environmental Satellites (GOES) System

Primary weather observation platform in the US providing continuous environmental data for weather forecasting and storm tracking.

QuickBird

Commercial satellite with high spatial resolution sensors operated by DigitalGlobe, contributing to mapping, agricultural planning, and military surveillance.

Other Remote Sensing Satellites

Include Envisat launched by ESA with instruments like ASAR and MERIS for sea forecasting and monitoring sea ice.

Spatial resolution

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

Spectral resolution

the number of spectral bands -- portions of the electromagnetic spectrum -- that a sensor can collect energy in

Temporal resolution

the revisit period of a satellite's sensor for a specific location on the Earth

Panchromatic sensor

a sensor measuring the visible portion of the spectrum, treating it as one band

Multispectral sensor

a sensor that collects information across several bands of the electromagnetic spectrum

Hyperspectral sensor

a sensor that collects information across very many narrow, contiguous bands

Swath

the strip of the Earth’s surface from which geographic data are collected by a satellite

GIS

Software systems with the capability for input, storage, manipulation/analysis, and output/display of geographic (spatial) information

Geographic Information Systems (GIS)

Software systems with the capability for input, storage, manipulation/analysis, and output/display of geographic (spatial) information

People

Essential individuals who design, program, maintain, and use GIS, making it functional and valuable

Data

Fundamental to geospatial technologies, consisting of spatial data (location of features) and attribute data (properties of features)

Spatial Data Models

Vector data model (Points, Lines, Polygons) and raster data model (grid cells/pixels) used to represent geographic features

Raster Data Model

Defines space as an array of equally sized cells (pixels) with unique values, used for continuous data representation

Vector Data Model

Uses points, lines, and polygons to represent geographic features, suitable for discrete data representation

Attribute Data

Descriptive information about geographic features, stored in attribute tables for linking properties to locations

Pixel

Smallest unit in a raster data model, representing a cell with a unique value

Resolution

Pixel size in ground units in a raster data model, determining the level of detail in the data

Point (vector)

Represents objects with a single (x, y) coordinate pair in a vector data model

Polygon (vector)

A feature in a vector data model depicted with a closed loop of (x, y) coordinates, enclosing an area.