hsdar: get.gaussian.response – R documentation

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get.gaussian.response

Gaussian response function

Description

Simulate Gaussian response function for band(s) of a (satellite) sensor. Each band is either defined by center and full-width-half-maximum values or by passing its upper and lower border.

Usage

get.gaussian.response(fwhm)

Arguments

fwhm

Object of class data.frame with three columns. See details and examples sections.

Details

The characteristics of the sensor must be passed as a data.frame with three columns: first column is used as name for bands, second with lower bounds of channels and third column with upper bounds (5% sensitivity). Alternatively, the data.frame may encompass band centre wavelength and full-width-half-maximum values of the sensor. Function will check the kind of data passed by partially matching the names of the data frame: If any column is named "fwhm" or "center", it is assumed that data are band centre and full-width-half-maximum values.

Value

Data frame with response values for all bands covering the entire spectral range of sensor passed to the function.

Author(s)

Lukas Lehnert

Examples

par(mfrow=c(1,2))
## Plot response function of RapidEye
plot(c(0,1)~c(330,1200), type = "n", xlab = "Wavelength [nm]", 
     ylab = "Spectral response")
data_RE <- get.gaussian.response(get.sensor.characteristics("RapidEye"))
xwl_response <- seq.int(attr(data_RE, "minwl"),
                        attr(data_RE, "maxwl"),
                        attr(data_RE, "stepsize"))
for (i in 1:ncol(data_RE))
  lines(xwl_response, data_RE[,i], col = i)
  
## Plot original response function
data_RE <- get.sensor.characteristics("RapidEye", TRUE)

plot(c(0,1)~c(330,1200), type = "n", xlab = "Wavelength [nm]", 
     ylab = "Spectral response")
xwl_response <- seq.int(attr(data_RE$response, "minwl"),
                        attr(data_RE$response, "maxwl"),
                        attr(data_RE$response, "stepsize"))
for (i in 1:nrow(data_RE$characteristics))
  lines(xwl_response, data_RE$response[,i], col = i)
  
## Simulate gaussian response for arbitrary sensor with 3 bands
sensor <- data.frame(Name = paste("Band_", c(1:3), sep = ""),
                     center = c(450, 570, 680),
                     fwhm = c(30, 40, 30))

## Plot response function
par(mfrow=c(1,1))
plot(c(0,1)~c(330,800), type = "n", xlab = "Wavelength [nm]", 
     ylab = "Spectral response")
data_as <- get.gaussian.response(sensor)
xwl_response <- seq.int(attr(data_as, "minwl"),
                        attr(data_as, "maxwl"),
                        attr(data_as, "stepsize"))
for (i in 1:3)
  lines(xwl_response, data_as[,i], col = i)

hsdar

Manage, Analyse and Simulate Hyperspectral Data

v1.0.3

GPL

Authors

Lukas W. Lehnert [cre, aut] (<https://orcid.org/0000-0002-5229-2282>), Hanna Meyer [ctb], Joerg Bendix [ctb]

Initial release

2020-08-04