Introduction Remote Sensing

GIMA: Geographical Information Management and Applications

Remote Sensing --> RS

EARTH OBSERVATION

RS is a tool; one of the sources of information ! Earth

Sensor at a distance

EM energy

GIS Geographical Information System

Well-considered combination of mutually referring data sets of various kinds of position-bound thematic data (database), software inclusive Requirement: the information layers match geometrically ==> OVERLAY STRUCTURE

1. topography 2. soils 3. geology 4. precipitation 5. land cover 6. vegetation 7. remote sensing data 8. surface temperature 9. hydrology 10. population 11. nature conservation 12. environment 13. digital terrain model 14. topographical map 15. ------------------- 16. ------------------- 17. -------------------

raster data

GIS file: field data (point measurements)

vector data

Meteosat: meteorological satellite

Meteosat image of Europe

Wageningen, Thematic Mapper Band 4 5 3

Rotterdam harbour, daytime

Rotterdam harbour, nighttime

The remote sensing system

A = source B = atmosphere C = object D = sensor E = reception F = data analysis G = final product

Source of EM radiation

100

10-1

10-2

10-3

10-4 0.2 0.5 2 10 1.0 5 20

radiation (Wcm-2 µm-1)

wavelength (µm)

REFLECTION EMISSION

emitted thermal radiation

reflected solar radiation

curves for an “average” object on Earth

EM Spectrum and Windows

200 µm 0.3 0.6 1.0 5.0 10 50 10m 100 1mm 1cm 1m

200 µm 0.3 0.6 1.0 5.0 10 50 10m 100 1mm 1cm 1m

multispectral scanners

microwave window

emission

optical window

lidar

reflection

photography

human eye

mic

row

aves

microwave radiometry

blocking effect of atmosphere

radar

atm

osph

eric

tr

ansm

ittan

ce

UV

blue

gr

een

red

NIR

MIR

M

IR

TIR

TIR

thermal scanners

VIS

wavelength

100

0

Active <-> Passive

RS using radiation emitted by objects: (PASSIVE)

RS using reflected solar radiation: (PASSIVE)

ACTIVE RS:

Principles imaging sensor systems

Pushbroom scanner Whiskbroom scanner

digital recording analogue recording digital recording

scanning mirror shutter

“point” detector

aerial image plane line array detector

imaging optics imaging optics

Camera (aerial photography)

imaging optics

The position of the spectral bands of some Remote Sensing sensor systems in the optical window

wavelength (µm)

red middle-

infrared near- infrared bl

ue

gree

n

dry soil

water wet soil vegetation re

flect

ance

(%)

SPOT HRG Panchromatic

Pan: IKONOS, Quickbird, GeoEye, WorldView

Meteosat NOAA AVHRR

Landsat TM

40

20

0 0.8

60

0.4 1.2 1.6 2.0 2.4

SPOT HRG multispectral

Multispectral: IKONOS, Quickbird, GeoEye, WorldView

Image Processing Options

Tape/DVD/CD: Screen: latent image → Visualization → picture 1

picture 2 ------- -------

picture n Options: e.g. spectral band selection filtering displaying band composites band ratioing contrast modification vegetation index computation histogram equalization classification grey scale enhancement texture analysis colour assignment segmentation density slicing geometric correction

principal components transformation

Example TM-image, band 4-3-2 (R,G,B)

RS Properties

Moreover:

overview region differences and coherence

variety of sensors, techniques, processing algorithms reproducible analysis

in addition to conventional mapping specified data for application up to date information

co-operation of human knowledge and machine operations

capability of monitoring with time series of data reveals changes (change detection)

the invisible becomes visible objective and quantitative data extrapolation of point measurements open up inaccessible regions integration with GIS

Synopsis

Flexibility

Actuality

Interactivity

Dynamics

MERIS image of Europe

Satellite based land cover classification

Dutch land cover data base LGN

LGN detail The Hague - Rotterdam

Global land cover classification - MODIS

254Unclassified

16Barren or Sparsely Vegetated

15Snow and Ice

14Cropland/Natural Vegetation Mosaic

13Urban and Built-Up

12Croplands

11Permanent Wetlands

10Grasslands

9Savannas

8Woody Savannas

7Open Shrubland

6Closed Shrubland

5Mixed Forest

4Deciduous Broadleaf Forest

3Deciduous Needleleaf Forest

2Evergreen Broadleaf Forest

1Evergreen Needleleaf Forest

0Water

255Fill Value

ColorClassLand Cover

254Unclassified

16Barren or Sparsely Vegetated

15Snow and Ice

14Cropland/Natural Vegetation Mosaic

13Urban and Built-Up

12Croplands

11Permanent Wetlands

10Grasslands

9Savannas

8Woody Savannas

7Open Shrubland

6Closed Shrubland

5Mixed Forest

4Deciduous Broadleaf Forest

3Deciduous Needleleaf Forest

2Evergreen Broadleaf Forest

1Evergreen Needleleaf Forest

0Water

255Fill Value

ColorClassLand Cover

Primary Productivity – 2000 - 2012

Next topics:

• Spectral signature • Multispectral scanning • Microwave remote sensing • Image pre-processing • Digital image processing

See: www.geo-informatie.nl/courses/gima_rs