Table 2

Image features used for level 1 and level 2 classifications
Classes Features Image Notes
Level 1 classification Open water Object mean band 4 (near infrared): threshold of 5.5% April Light in band 4 absorbed by water
Built up & bare ground; wet vegetation types; dry vegetation types Object mean band 3 (red) April Vegetation type discrimination
Object mean band 2 (green) November Identification of healthy vegetation
Object mean band 3 November Vegetation type discrimination
Object mean band 5 (mid infrared) November Vegetation and soil moisture content
Object mean band 7 (mid infrared) November Identification of built up areas and bare ground
Object length/width
NDVI difference, January to November Differentiation of vegetation types
Level 2 classification Woodland & dense savannah*; crops & open savannah* Object mean band 2 April Related to healthy vegetation, biomass, plant type or vegetation moisture content
Object mean band 3 April
Object mean band 4 April
Object mean band 5 April
NDVI difference, January to April, January to November and April to November Differentiation of vegetation types
Seasonally flooding grassland**; lake fringe swamps** Object mean band 4 November Identification of vegetation and soil moisture content, biomass, plant vigour and water
Object mean band 5 November

All classifications used a nearest neighbour algorithm with the exception of open water, which utilised a threshold [26,27].

*Obtained using sub-classifications of the “dry vegetation types” class.

**Obtained using sub-classifications of the “wet vegetation types” class.

Wardrop et al.

Wardrop et al. BMC Infectious Diseases 2012 12:316   doi:10.1186/1471-2334-12-316

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