GIS and Remote Sensing - Resolution, Platforms and Sensors PDF

Module M.SIA.I14M GIS and Remote Sensing for Agriculture L7: Resolution, Platforms and Sensors Dr Jayan Wijesingha [email protected] +49 561 804-1245 Four resolutions Spatial resolution What area and how detailed Spectral res...

Module M.SIA.I14M GIS and Remote Sensing for Agriculture L7: Resolution, Platforms and Sensors Dr Jayan Wijesingha [email protected] +49 561 804-1245 Four resolutions Spatial resolution What area and how detailed Spectral resolution What colours/bands Radiometric resolution How is the colour depth Temporal resolution How often revisit 2 Spatial resolution How much is the edge length of a pixel in the image shows in the actual ground It describes in unit meters Low spatial resolution – greater than 30 m Medium spatial resolution – 2 – 30 m High spatial resolution – less than 2 m The higher the spatial resolution and the finer the grid is, the degree of recognizable details on the earth’s surface 3  Spatial resolution https://www.seos-project.eu/remotesensing High resolution Medium resolution Low resolution 4 1 meter resolution 10 meter resolution 100 meter resolution Spectral resolution How many spectral bands are in the data and how is the band width Panchromatic – 1 band RGB – 3 bands Multispectral – 3+ bands (e.g., RGB + NIR) Hyperspectral – Hundreds of bands 5 https://wiki.tum.de/display/zfp/Hyper-+and+multispectral+imaging Radiometric resolution Number of digital level (grey levels) the a sensor can use to express variability of brightness within the data Expressed using number of bits (binary numbers) 8 bits – 256 values (28) 11 bits – 2048 values (211) The finer the radiometric resolution, the more sensitive it is to detect small difference in reflected energy 6 Radiometric resolution By Ant Beck - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=23016361 7 Temporal resolution Time interval between two identical flights over the same area, or revisit time Mostly concern in satellite remote sensing Landsat – 16 days SPOT – 26 days METEOSAT – 15 mins MODIS – 24 to 48 Hours 8 Platforms Space-borne (e.g., satellite) Air-borne (e.g., manned aircraft, UAV) Hand-held (e.g., field spectrometer) 9 Satellite orbits https://seos-project.eu/remotesensing 10 Satellite orbits Geostationary Polar orbit Orbit time is 24 hours Pass near the poles Same speed as the 400 – 900 km from earth’s rotation speed the equator 36000 km from the Inclination is 98º to equator the equator Meteorological, Orbit time is 100 communication minutes 11 Sensors Some satellites carry more than one sensor ENVISAT consisted 6 sensors Different type of sensors Cameras Line scanner Whisk broom vs push broom Naming differences Sensors are named by the satellite name e.g., IKONOS By the exact name of the sensor e.g., MODIS is a sensor in both Aqua and Terra satellite By combination of both satellite and sensor name e.g., LANDSAT 7 ETM+ 12 Landsat https://appliedsciences.nasa.gov/media/4153 13 Landsat https://landsat.gsfc.nasa.gov/satellites/landsat-9/landsat-9-bands/ https://youtu.be/M_263U_ovkQ 14 Landsat 8 15 Copernicus Program - Sentinel https://gisgeography.com/sentinel-satellites-copernicus-programme/ 16 Sentinel 2 Land monitoring and climate change Multispectral instrument 13 Spectral bands 10 m – 4 bands 20 m – 6 bands 60 m – 3 bands 2 satellite constellation 2A and 2B Revisit time is 10 days only with single satellite 5 days with both 17  Sentinel 2 https://www.esa.int/ESA_Multimedia/Images/2016/05/African_mosaic 18 Sentinel 2 19 Sentinel 3 Sea surface topography, sea and land surface temperature, and ocean and land surface colour Four instruments OLCI: Ocean and Land Colour Instrument SLSTR: Sea and Land Surface Temperature Instrument SRAL: SAR Radar Altimeter MWR: Microwave Radiometer. 20 Sentinel 3 https://sentinels.copernicus.eu/web/sentinel/user-guides/sentinel-3-olci/applications/maritime-monitoring 21 Sentinel 1 RADAR mission C band data 3 satellite constellation 1A, 1B and 1C https://medium.com/sentinel-hub/sentinel-1-data-available-on-aws-and-through-sentinel-hub-ecc51c910db6 22 MODIS (Moderate Resolution Imaging Spectroradiometer) Same sensor in two satellites Terra (1999) Aqua (2002) 36 channels Different spatial resolution 250 m, 500 m, 1000 m Many product are developed NPP LAI 23 MODIS https://earthobservatory.nasa.gov/images/36011/cyclone-06b-over-sri-lanka-and-india 24