`preProcess_removeTrend.Rd`

Level a breech face impression surface matrix by a conditional statistic

`preProcess_removeTrend(x3p, statistic = "mean", ...)`

- x3p
an x3p object containing the surface matrix of a cartridge case scan

- statistic
either "mean" or "quantile"

- ...
arguments to be set in the quantreg::rq function if statistic = "quantile" is set. In this case, tau = .5 and method = "fn" are recommended

an x3p object containing the leveled cartridge case scan surface matrix.

```
#Process fadul1.1 "from scratch" (takes > 5 seconds to run)
if (FALSE) {
nbtrd_link <- "https://tsapps.nist.gov/NRBTD/Studies/CartridgeMeasurement/"
fadul1.1_link <- "DownloadMeasurement/2d9cc51f-6f66-40a0-973a-a9292dbee36d"
fadul1.1 <- x3ptools::read_x3p(paste0(nbtrd_link,fadul1.1_link))
fadul1.1_extCropped <- preProcess_crop(x3p = fadul1.1,
region = "exterior",
radiusOffset = -30)
fadul1.1_intCroped <- preProcess_crop(x3p = fadul1.1_extCropped,
region = "interior",
radiusOffset = 200)
fadul1.1_leveled <- preProcess_removeTrend(x3p = fadul1.1_intCroped,
statistic = "quantile",
tau = .5,
method = "fn")
x3pListPlot(list("Original" = fadul1.1,
"Ext. Cropped" = fadul1.1_extCropped,
"Ext. & Int. Cropped" = fadul1.1_intCroped,
"Cropped and Leveled" = fadul1.1_leveled))
}
```