A gaussian filter is fit to the surface measurements and residuals are calculated. The most extreme 0.25% of residuals are filtered from further consideration. The result is called the raw signature of the bullet land.
cc_fit_gaussian(ccdata, span = 600)The crosscut as returned from x3p_to_df
The size, in microns, of the smoothing window. Defaults to 600, which is 24% of 2500 microns; approximately the same size as a 9mm land.
a list of a data frame of the original bullet measurements extended by gaussian filtration, residuals, and two plots: a plot of the fit, and a plot of the bullet's land signature.
library(dplyr)
#>
#> Attaching package: ‘dplyr’
#> The following objects are masked from ‘package:stats’:
#>
#> filter, lag
#> The following objects are masked from ‘package:base’:
#>
#> intersect, setdiff, setequal, union
ccdata <- data_frame(
x = seq(0, 6000, 1),
value = 10 - (3 - x / 1000)^2 + rnorm(length(x), sd = .25)
)
#> Warning: `data_frame()` was deprecated in tibble 1.1.0.
#> Please use `tibble()` instead.
#> This warning is displayed once every 8 hours.
#> Call `lifecycle::last_lifecycle_warnings()` to see where this warning was generated.
cc_fit_gaussian(ccdata = ccdata)
#> # A tibble: 6,001 × 7
#> x value fitted raw_sig se abs_resid chop
#> <dbl> <dbl> <dbl> <dbl> <lgl> <dbl> <lgl>
#> 1 0 0.931 1.53 -0.595 NA 0.595 FALSE
#> 2 1 0.777 1.53 -0.751 NA 0.751 FALSE
#> 3 2 0.568 1.53 -0.962 NA 0.962 TRUE
#> 4 3 0.961 1.53 -0.572 NA 0.572 FALSE
#> 5 4 1.07 1.53 -0.462 NA 0.462 FALSE
#> 6 5 0.740 1.54 -0.797 NA 0.797 FALSE
#> 7 6 0.939 1.54 -0.600 NA 0.600 FALSE
#> 8 7 0.739 1.54 -0.803 NA 0.803 TRUE
#> 9 8 1.05 1.54 -0.491 NA 0.491 FALSE
#> 10 9 0.946 1.55 -0.600 NA 0.600 FALSE
#> # … with 5,991 more rows