Initial weights according to qc

Source: R/qcFUN.R

  • getBits: Extract bitcoded QA information from bin value

  • qc_summary: Initial weigths based on Quality reliability of VI pixel, suit for MOD13A1, MOD13A2 and MOD13Q1 (SummaryQA band).

  • qc_5l: Initial weights based on Quality control of five-level confidence score, suit for MCD15A3H(LAI, FparLai_QC), MOD17A2H(GPP, Psn_QC) and MOD16A2(ET, ET_QC).

  • qc_StateQA: Initial weights based on StateQA, suit for MOD09A1, MYD09A1.

  • qc_FparLai: For MODIS LAI

  • qc_NDVI3g: For AVHRR NDVI3g

  • qc_NDVIv4: For AVHRR NDVIv4

getBits(x, start, end = start)

qc_summary(QA, wmin = 0.2, wmid = 0.5, wmax = 1)

qc_StateQA(QA, wmin = 0.2, wmid = 0.5, wmax = 1)

qc_FparLai(QA, FparLai_QC = NULL, wmin = 0.2, wmid = 0.5, wmax = 1)

qc_5l(QA, wmin = 0.2, wmid = 0.5, wmax = 1)

qc_NDVIv4(QA, wmin = 0.2, wmid = 0.5, wmax = 1)

qc_NDVI3g(QA, wmin = 0.2, wmid = 0.5, wmax = 1)

qc_SPOT(QA, wmin = 0.2, wmid = 0.5, wmax = 1)

Arguments

x

Binary value

start

Bit starting position, count from zero

end

Bit ending position

QA

quality control variable

wmin

Double, minimum weigth (i.e. weight of snow, ice and cloud).

wmid

Dougle, middle weight, i.e. marginal

wmax

Double, maximum weight, i.e. good

FparLai_QC

Another QC flag of MCD15A3H

Value

A list object with

  • weigths: Double vector, initial weights.

  • QC_flag: Factor vector, with the level of c("snow", "cloud", "shadow", "aerosol", "marginal", "good")

Details

If FparLai_QC specified, I_margin = SCF_QC >= 2 & SCF_QC <= 3.

Note

qc_5l and qc_NDVIv4 only returns weight, without QC_flag.

References

https://developers.google.com/earth-engine/datasets/catalog/MODIS_006_MOD13A1

https://developers.google.com/earth-engine/datasets/catalog/MODIS_006_MCD15A3H

Erwin Wolters, Else Swinnen, Carolien Toté, Sindy Sterckx. SPOT-VGT COLLECTION 3 PRODUCTS USER MANUAL V1.2, 2018, P47

See also

qc_sentinel2()

Examples

set.seed(100)
QA <- as.integer(runif(100, 0, 2^7))

r1 <- qc_summary(QA, wmin = 0.2, wmid = 0.5, wmax = 1)
r2 <- qc_StateQA(QA, wmin = 0.2, wmid = 0.5, wmax = 1)
r_5l <- qc_5l(QA, wmin = 0.2, wmid = 0.5, wmax = 1)
r_NDVI3g <- qc_NDVI3g(QA, wmin = 0.2, wmid = 0.5, wmax = 1)
r_NDVIv4 <- qc_NDVIv4(QA, wmin = 0.2, wmid = 0.5, wmax = 1)