Remote sensing for Earth observation

Dr Nigel Trodd Coventry 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?

Albedo Temperature Height (relative) Passive Reflectance @ visible & NIR wavelengths MIR, Thermal & Microwave emissions Stereo photogrammetry Active Radar altimetry Lidar

albedo

Climate change due to reduced snow albedo caused by soot

EOS Aqua AMSR-E

SST

Advanced Microwave Scanning Radiometer

Global DEM Shuttle 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 scatterometer Alaska 2000

What preparation is necessary?

Cosmetic infilling of saturated pixels & drop-outs Radiometric balancing (destriping) & sensor calibration Atmospheric 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

Summary & conclusions

Remote sensing generates 2D & 2.5D GI products … at local to global scales using optical & microwave EMR Images for Earth observation require • error detection & elimination • calibration & georegistration