Thematic Land Processing

Radiometric Indices

Radiometric indices are quantitative measures of features that are obtained by combining several spectral bands, features that are not otherwise obvious if using only one band.

The indices provided by the Optical Toolbox, detailed below, are grouped into three categories:

These indices share the same graphical interface, as in the next figure:

Parameter Description
Resample Type In case when the bands involved in the calculus are not of the same resolution, this represents the choice of resampling the bands: either use the lowest resolution band as reference, or the highest resolution one.
Upsampling Method If the resampling will be done for the highest resolution band, this is the method used for upsampling lower resolution bands.
Can be one of: Nearest neighbour, Bilinear, Bicubic.
Downsampling Method If the resampling will be done for the lowest resolution band, this is the method used for downsampling higher resolution bands.
Can be one of: First, Min, Max, Mean, Median.
[Bx] factor The weight given to the [Bx] band pixel value.
[Bx] The selected band [Bx]

In case of bands with different resolutions are employed, a message is displayed at the bottom of the window, as it can be seen on the above figure.
If no resample is needed, the parameters Resample Type, Upsampling Method and Downsampling Method will be disabled.
The parameters Upsampling Method and Downsampling Method are mutually exclusive.


The following table summarizes the radiometric indices provided by the toolbox:

Name

Purpose/Classification

Short Description

Type

NDVI
Normalized Difference Vegetation Index
The well-known classical vegetation index. The NDVI composes a measurement for the photosynthetic activity and is strongly in correlation with density and vitality of the vegetation
Vegetation Index

DVI
Difference Vegetation Index
This index is sensitive to the amount of vegetation
Vegetation Index

RVI
Ratio Vegetation Index
The simplest ratio-based index, it is also called the Simple Ratio (SR). It indicates the amount of vegetation. It also reduces the effects of atmosphere and topography
Vegetation Index

PVI
Perpendicular Vegetation Index
This index could be considered a generalization of the DVI, which allows for soil lines of different slopes.
Vegetation Index

IPVI
Infrared Percentage Vegetation Index
This index is functionally equivalent to NDVI and RVI, but it only ranges in value from 0.0 - 1.0
Vegetation Index

WDVI
Weighted Difference Vegetation Index
WDVI is a mathematically simpler version of PVI, but it has an unrestricted range
Vegetation Index

TNDVI
Transformed Normalized Difference Vegetation Index
TNDVI algorithm indicates a relation between the amount of green biomass that is found in a pixel
Vegetation Index

GNDVI
Green Normalized Difference Vegetation Index
GNDVI is more sensible than NDVI to identify different concentration rates of chlorophyll, which is highly correlated at nitrogen.
Vegetation Index

GEMI
Global Environmental Monitoring Index
Was developed to eliminate the need for a detailed atmospheric correction by constructing a stock atmospheric correction for the vegetation index
Vegetation Index

ARVI
Atmospherically Resistant Vegetation Index
This index takes advantage of the different scattering responses from the blue and red band to retrieve information regarding the atmosphere opacity
Vegetation Index

NDI45
Normalized Difference Index
This index algorithm is more linear, with less saturation at higher values than the NDVI.
Vegetation Index

MTCI
Meris Terrestrial Chlorophyll Index
This index was developed for estimating chlorophyll content from MERIS (Medium Resolution Imaging Spectrometer) data
Vegetation Index

MCARI
Modified Chlorophyll Absorption Ratio Index
This index was developed to be responsive to both leaf chlorophyll concentrations and ground reflectance.
Vegetation Index

REIP
Red-Edge Inflection Point index
This index was developed for applications in biomass and nitrogen (N) uptake measurment/management in heterogeneous fields.
Vegetation Index

S2REP
The Sentinel-2 Red-Edge Position index
This index is based on linear interpolation as presented by Guyot and Baret (1988). The reflectance at the inflexion point is estimated and in turn, the REP is retrieved through interpolation of S-2 band 5 and 6 which are positioned on the RE slope.
Vegetation Index

IRECI
Inverted Red-Edge Chlorophyll Index
This index algorithm incorporates the reflectance in four bands to estimate canopy chlorophyll content
Vegetation Index

PSSRa
Pigment Specific Simple Ratio (chlorophyll) index.
This index was developed to investigate the potential of a range of spectral approaches for quantifying pigments at the scale of the whole plant canopy.
Vegetation Index

SAVI
Soil Adjusted Vegetation Index
This index attempts to be a hybrid between the ratio-based indices and the perpendicular indices
Soil Index

TSAVI
Transformed Soil Adjusted Vegetation Index
This index assumes that the soil line has arbitrary slope and intercept, and it makes use of these values to adjust the vegetation index
Soil Index

MSAVI
Modified Soil Adjusted Vegetation Index
The basic idea of MSAVI was to provide a variable correction factor L. The correction factor used is based on the product of NDVI and WDVI
Soil Index

MSAVI2
The second Modified Soil Adjusted Vegetation Index
Basically, it is used an iterative process and substitute 1 - MSAVI(n-1) as the L factor in MSAVI(n).
They then inductively solve the iteration where MSAVI(n) = MSAVI(n-1)
Soil Index

BI
Brightness Index
This index is representing the average of the brightness of a satellite image
Soil Index

BI2
The second Brightness Index
This index is representing the average of the brightness of a satellite image. The result looks like a panchromatique image with the same resolution of the original image.
Soil Index

RI
Redness Index
The Redness Index algorithm was developed to identify soil colour variations
Soil Index

CI
Colour Index
The Colour Index algorithm was developed to differentiate soils in the field
Soil Index

NDWI
Normalized Difference Water Index
This index is a measure of liquid water molecules in vegetation canopies that interacted with the incoming solar radiation.
Water Index

NDWI2
The second Normalized Difference Water Index
This index was developed to detect surface waters in wetland environments and to allow for the measurement of surface water extent.
Water Index

MNDWI
Modified Normalized Difference Water Index
This index was developed to enhance open water features, while efficiently suppressing and even removing built-up land noise as well as vegetation and soil noise.
Water Index

NDPI
Normalized Difference Pond Index
The NDPI algorithm makes it possible not only to distinguish small ponds and water bodies (down to 0.01 ha), but also to differentiate vegetation inside ponds from that in their surroundings
Water Index

NDTI
Normalized Difference Turbidity Index
This index was developed to allow for the measurement of water turbidity.
Water Index