Image Data Purchase and Pre-processing

Litia GaunavouSPC-SOPAC

Pre-Processing

• Image Stitching

• Ortho-Correction

• Haze removal

• Atmospheric correction

• Pan-sharpening

Image Stitching

Stitched Image

Ortho Correction

• Ortho correction requires a DTM• the DTM should have similar scale

as image data

New Satellites: GeoEye-1WorldView-1, WorldView-2

• High geo-accuracy ~ 5m1. Star tracker2. Advanced GPS position

• Ortho Correction required to activate high geo-accuracy

Haze Removal

Raw LandSat 4 TM (Fiji – 1991) Haze Corrected LandSat 4 TM

Atmospheric Correction

- View Angle

- DEM

- Sensor type

- Calibration data

- Sun angle

Corrected Image

Raw ALOS Image (Fiji 2007) ALOS Image + atmospheric correction

IHS Transformation

• Intensity• Hue• Saturation

IHS Transformation and Re-Transformation in ERDAS

Imagine

Red

Green

Blue

Intensity

Hue

Saturation

Red

Green

Blue

Pan-Sharpening

Red

Green

Blue

PanchromaticImage Data

Intensity

Hue

Saturation Saturation

Hue

Normal Bands Pan-sharpened IMG

IHS Resolution Merge

Red

Green

Blue

Resolution increase

Casuarina

Casuarina

Bands: 1, 2, 3, pan-sharpenednatural colour combination

Casuarina

Bands: 2, 3, 4 pan-sharpenedfalse colour infrared

Casuarina

Vegetation Index Bands: 4 – 3 / 4 + 3

Radiometric Resolution

CoastalYellowBlue

Red Edge

GreenNear IR 1

Red Near IR 2

BND 2, 3, 5 Natural C

BND 3, 5, 7 FCIR

BND 3, 5, 6 FCIR RE

BND 3, 5, 8 FCIR (IR2)

Current WV-2 Bundle Data Backdrop Products:

• Pan-sharpened natural colour• Pan-sharpened false colour IR• Pan-sharpened false colour RE• Vegetation index red / near IR• Vegetation index red / RE

Vinaka