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Remote sensing for Earth observation
Dr Nigel TroddCoventry University
What is remote sensing?
remote sensing has been described as the means of sensing or measuring things (characteristics) without coming into direct contact with the object or phenomenon
What is Earth observation?
observing our planet is a pre-requisite to a better understanding of its changes and the natural and anthropogenic processes that cause those changes
Aim & objectives
To understand remote sensing as a source of geodata for mapping & monitoring the Earth
Examine the role of remote sensing for Earth observation
Exemplify aspects of the geodata stream
What are the principles of remote sensing?
1. Source of electromagnetic radiation
2. Interaction with target
3. Measurement by sensor mounted on platform
Multispectral reflectance
EMR sources
Active remote sensing Artificial source of EMR Radar Lidar
Passive remote sensing Natural source of EMR Sun (primary source for optical RS) EMR emitted from Earth surface
What properties can be measured?
Passive Active
Albedo Reflectance @ visible & NIR wavelengths
Temperature
MIR, Thermal & Microwave emissions
Height (relative)
Stereo-photogrammetry
Radar altimetry
Lidar
albedo
Climate change due to reduced snow albedo caused by soot
EOS Aqua AMSR-E SSTAdvanced Microwave Scanning Radiometer
Global DEMShuttle Radar Topography Mission
2000
What GI can be generated?
Extracting features e.g. buildings,
roads
Land cover / land use classification
Estimation of biophysical
properties e.g. biomass, ice-thaw
Santa Cruz de la Sierra, Bolivia
QuikSCAT Seawinds scatterometerAlaska 2000
What preparation is necessary?
Cosmetic infilling of saturated pixels & drop-outsRadiometric balancing (destriping) & sensor calibrationAtmospheric correction
How do you integrate images into a spatial database?
Georeferencing Plane projection Local datum &
coordinate system
Co-registration Rubber-sheet
transformation Nearest neighbour
resampling
Orthorectification
Topography DN pixel
geometry foreshortening
Remote sensing generates 2D & 2.5D GI products
… at local to global scalesusing optical & microwave
EMR
Summary & conclusions
Images for Earth observation require• error detection & elimination• calibration & georegistration