"GEOG 1100 Remote Sensing and GISRemote Sensing • Remote sensing isthe science ofacquiringinformation about aplace or processwithout directphysical contact • Normally useselectromagneticEarth Observing 1 (NASA) radiationRemote Sensing • Three sources ofelectromagnetic radiationused for remote sensing – Reflected solar radiation – Emitted radiation from theEarth – The sensor itself • Passive: uses reflectedsolar radiation or emittedradiation • Active: sensor producesradiationTOPEX-Poseidon (NASA)Remote Sensing • Platform – Carries the sensor – Satellite or aircraft Terra satellite, platform for MODIS• Sensor produces anand ASTER (NASA) image ER-2 (NASA)Image Photo/PictureThe Electromagnetic Spectrum Arny, 2000Seven Regions of the ElectromagneticSpectrum Useful for Remote Sensing • Ultraviolet • Visible • Near Infrared • Shortwave Infrared • Thermal Infrared • Microwave • RadiowaveSeven Regions of the ElectromagneticSpectrum Useful for Remote Sensing • Ultraviolet • Visible Reflected Solar Radiation • Near Infrared • Shortwave Infrared • Thermal Infrared • Microwave • Radiowavehttp://www.naturfotograf.com/UV_HYPE_PER.html © Bjørn Rørslett/NNhttp://www.naturfotograf.com/UV_HYPE_PER.html © Bjørn Rørslett/NNSeven Regions of the ElectromagneticSpectrum Useful for Remote Sensing • Ultraviolet • Visible • Near Infrared • Shortwave Infrared • Thermal Infrared Emitted Radiation • Microwave • RadiowaveSeven Regions of the ElectromagneticSpectrum Useful for Remote Sensing • Ultraviolet • Visible • Near Infrared • Shortwave Infrared Active Remote Sensing • Thermal Infrared • Microwave • RadiowaveAtmospheric Limitations • Atmospheric gases absorb some regionsof the electromagnetic spectrum • We can only use remote sensing within“atmospheric windows”Remote Sensing and Wavelength • Shorter wavelengths have more energy – Ultraviolet radiation has more energy thanvisible – Thermal infrared has more energy thanmicrowaveRemote Sensing and Wavelength • Sensors measure one or more bands thatcover a range of wavelengthsSpatial Resolution • The size on the ground of asingle pixel from an image• Spatial resolution is a30 m function of: – Wavelength – Altitude 30 m – Application – Technological limitationsTypical Spatial Resolutions • Global monitoring – GOES: 1 km visible, 4 km thermal infrared – MODIS: 500 m visible, 1 km thermal infrared • Earth resource – Landsat TM: 30 m visible, 60 km thermal infrared • Satellite high resolution mapping – Worldview-2: 50 cm visible • Airborne high resolution mapping – 15 cm to 1 mGOES West visibleimage, 1 km (NOAA)MODIScompositecovering Utah,500 m (NASA)Landsat 7 ETM+, 30 mToussaint L’Ouverture International Airport, Haiti; January 2010 GeoEye-1, 0.5 mGoogleMountainViewCampus,Google EarthGoogle Earth Base Data Layer • Landsat TM (30 m) • SPOT (2.5 m) • Worldview-2 (50 cm) • Aerial photography https://www.planet.com/flock1/Temporal Resolution • How often a satellite can acquire an imageof a location • There is a tradeoff between temporal andspatial resolutionTypical Temporal Resolutions • Global monitoring – GOES: 15 minutes – MODIS: once per day • Earth resource – Landsat TM: once every 16 days • Satellite high resolution mapping – Worldview-2: once every several days • Airborne high resolution mapping – ?MODIS coverage for 1 day (NASA)Abilities and Limitations of RemoteSensing?Abilities of Remote Sensing • Doesn’t require a physical presence • Not limited to visible wavelengths • Global coverage with relatively little effort • Allows detection of changes over timeLimitations of Remote Sensing • Very limited abilities to look past theEarth’s surface • Limits on spatial and temporal resolutions • High initial cost • Reference data still requiredCommon Types of RemoteSensing • Multispectral – Used for mapping land cover – Reflected solar radiation (passive) – Multiple bands in visible, NIR,SWIR • Thermal – Used for mapping temperature – Emitted radiation (passive) – Thermal IR, microwave • Radar – Used for mapping surfaceroughness, water content, height Icesat (NASA) – “active microwave” • Lidar – Used for mapping height – Active, visible or NIRTime for a break!GIS • Geographic Information Systems • A means by which geographic analysis isconducted • System with three key components – Computer hardware and software – Geospatial data – Trained analystComputer Hardware & Software • Hardware – Desktop computer – Survey collector – Mobile phone • Software – ArcGIS – QGIS – Google Earth – Bing MapsGeospatial Data • Data that have a spatial locationassociated with them • Two “data models” – Vector: points, lines, or polygons – Raster: cellsTrained Analyst • You! • Training matters • Experience matters more • Career areas – Government – highway department – Private – marketing, fossil fuel development – Academia – research, overlap with privateand government GIS • GIS enables: – Geospatial data visualization (e.g. maps) – Geospatial analysis (e.g. geostatistics) – Speed in data handling • Key for modern analysis and visualizationGIS • Example GIS projectshttp://akcenter.org/gis-center/http://icdukraine.com/services-view/gis-projects/http://spatialityblog.com/2012/05/04/putting-transit-gis-data-to-use/GIS • Some things that aren’t GIS: – GPS – Maps (sometimes) – GIS Software itselfBenefits of GIS • Non-static – GIS allows for dynamic data • Standardized platform • Standardized data and practices – sort of • Rapid workflow – faster with automation • Improved decision-making support • Application flexibility – can have multipleprojects with same data, consistent acrossallDrawbacks of GIS • Data and software can be costly • Steep learning curve – experience! • Doesn’t provide absolute solutions – mustbe provided by analyst • Rooted in computer and earth sciences,limited capabilities in social research • It’s a still a young fieldFuture of GIS • GIS-related fields are growing (14-29%over 212-2022 expected) • Expanding into new industries – Can find work in nearly any industry • Median pay in 2012: $39,670-$74,760 – Most GIS-related jobs require a Bachelor’sdegree"