ATCOR3: Atmospheric Correction for Rugged Terrain

Litia Gaunavou SPC-SOPAC

Softwarea) Spectra Module

b) Haze Removal

c) Atmospheric and Topographic Correction General

d) Value Adding Products

Haze Removal 1

- Analysing ration near infra-red, blue where the near infra-red is more affected by haze

Masking of image

Raw Landsat Image Clear - Areas/Haze Mask

Haze Removal 2 & 3

- Calculate “clear line” from not affected areas

Haze Removal 4

Raw Landsat TM Image HOT levels

Haze Removal 5

- Changing imageappearance for maskedareas by shifting pixelvalues in relation to “clear line”

Result

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

Result

Raw ALOS (Fiji 2007) Haze Corrected ALOS

Limitations:

• Needs both clear and hazy areas

• Does remove haze but not clouds

• Does not work over water

• Requires multispectral image data

Spectra Module

Relief, Moisture, Reflectance

EastWest

Atmospheric Correction 3

- Path radiance

- Pixel radiation

- Adjacency radiation

- Terrain radiation

Atmospheric Correction 3 - View Angle

- DEM

- Sensor type

- Calibration data

- Sun angle

Applying ATCOR

View Angle

Different viewangles will be analyzed Differently

DEM

- Most critical parameter in ATCOR3

- Used to calculate the different reliefs

- Used to derive terrain files

Slope

Aspect

Skyview

Shadow

DEM ComponentsGeneration of terrain files

Slope

Aspect

Shadow

Sky view

Artefacts

- Artefacts in the output

data

Calibration data- Stores the band specific radiometric calibration values for each

supported sensor

- Provided by the satellite vendor

Sun Angle- Calculated from the acquisition day and time of the image

ATCOR3 Results

Raw Landsat 4 TM (Fiji 1991) Landsat 4 TM (Fiji) + ATCOR3

ATCOR3 Results

Raw ALOS Image (Fiji 2007) ALOS Image + ATCOR3

ATCOR3 Results

Raw ALOS image

ALOS image + ATCOR3

ATCOR3 Summary• Produces sharp and brilliant satellite

images

• Compares multi-spectral images with similar spectral bands.

• Improves the results of change detection and classification algorithms

Recommendation:• Production of good quality DTMs gain

importance

• Purchase of bundle data gain importance

• SPC-SOPAC conducts atmospheric correction for member countries !

Thank You

Questions?