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