sits (version 0.10.0)

sits_ndvi_arima: NDVI filter with ARIMA model

Description

This function tries to remove clouds in the NDVI band of a time series. It looks for points where the value of the NDVI band goes down abruptly. These points are those whose difference is more than a cutoff value which is set by the user. Then it applies an spline interploation. Finally, the function applies a whitakker smoother.

Usage

sits_ndvi_arima(
  data = NULL,
  cutoff = -0.25,
  p = 0,
  d = 0,
  q = 3,
  bands_suffix = "ar",
  apply_whit = TRUE,
  lambda_whit = 1
)

Arguments

data

Time series data and metadata (only the "NDVI" band).

cutoff

Maximum acceptable value of a NDVI difference.

p

Order (number of time lags) of the autoregressive model.

d

Degree of differencing (the number of times the data has had past values subtracted).

q

Order of the moving-average model.

bands_suffix

Suffix to rename the filtered bands.

apply_whit

Apply the whittaker smoother after filtering? (logical)

lambda_whit

Lambda parameter of the whittaker smoother.

Value

A sits tibble with same samples and the new bands.

Examples

# NOT RUN {
# Select the NDVI band of a point
# Apply the filter
point_ar <- sits_ndvi_arima(point_ndvi)
# Merge the filtered with the raw data
point2 <- sits_merge(point_ndvi, point_ar)
# Plot the result
plot(point2)
# }